Calculators
Figures that run on this device. Finance, math, dates, health, everyday, science, and construction pages apply a formula to the numbers you type. Output is informational, not tax, lending, medical, investment, or structural advice.
298 tools
Categories
Finance
Start in finance calculators for investment, loans, tax, income, and business pages.
Math, dates, and everyday
Open math for scientific, percentage, statistics, and geometry. Date and time covers age, business days, sunrise, and timesheets. Health is BMI, BMR, macros, and related estimates. Everyday has tip, GPA, and pace. Science groups Ohm's law, dilution, and related lab arithmetic. Construction groups concrete, paint, stairs, and other site estimates. Those construction figures are not structural design.
Figures, not advice
These pages apply a formula to the numbers you type. They do not load live rates or a lender schedule. Confirm a decision where it actually binds you. See the disclaimer.
Calculator groups
Construction
- Land Area Calculator Rectangle arithmetic for lots: square feet, square meters, acres, and hectares. A surveyor is required for a legal area. This is not a GIS map and not a plat.
- Asphalt Sealer Calculator Gallons equal area divided by coverage, times coats. Coats stay from 1 to 5. Porous pavement drinks more product. Estimate only, not a permit, code check, or engineered design.
- Asphalt Calculator Volume is area times thickness in feet. Tons equal volume times density divided by 2000. Default density is 145 lb per cubic foot. Estimate only, not a permit, code check, or engineered design.
- Baluster Calculator Pitch is baluster width plus max clear gap. Spaces ceil from rail length over pitch. Balusters between ends equal spaces minus one. Estimate only, not a permit, code check, or engineered design.
- Board and Batten Calculator Net wall area subtracts openings. Boards ceil across wall length with waste. Battens sketch as boards minus one. Estimate only, not a permit, code check, or engineered design.
- Board Feet Calculator A board foot is a volume unit for lumber: thickness in inches times width in inches times length in feet, divided by 12, times the piece count. Nominal sizes are not dressed sizes. Estimate only, not a mill ticket or grade stamp.
- Brick Calculator Net wall area is length times height minus openings. Divide by brick length times brick height. Waste percent rounds the buy count up. Use the same unit for the wall and the brick face. Estimate only, not a bond schedule.
- Concrete Block Calculator Net wall area subtracts openings. Divide by block face, apply waste from 0 to 40 percent, and round up. A common CMU face is 16 by 8 in, or about 1.333 by 0.667 ft. Estimate only, not a permit, code check, or engineered design.
- Concrete Calculator Slab volume is length times width times depth. A cylinder is π r² h. Cubic yards divide cubic feet by 27. Waste is 0 to 50 percent. This is an estimate, not structural design or code approval.
- Cubic Inches Calculator Cubic inches equal length times width times height when every side is inches. The page also shows cubic feet, cubic centimeters, and liters. Estimate only, not a permit, code check, or engineered design.
- Cubic Yards Calculator Box mode multiplies length, width, and depth in one unit, then reports yd³, ft³, and m³. Convert mode scales a typed volume among yd³, ft³, m³, and in³. Estimate only, not a permit, code check, or engineered design.
- Deck Flooring Calculator Deck area is length times width. Divide by board width times board length, apply waste from 0 to 40 percent, and round up. Gaps and picture-frame borders are omitted. Estimate only, not a permit, code check, or engineered design.
- Drywall Calculator Wall area is length times height times the number of walls. Divide by sheet length times sheet width, then apply waste and round up. Openings are omitted. Estimate only, not a hanging plan or code approval.
- Excavation Calculator Box volume for a trench or pad: length times width times depth, then multiplied by 1 plus waste or swell percent. Output is ft³, yd³, and m³. Optional tons if you type density. Estimate only, not a cut-and-fill design.
- Fence Calculator A straight run divides into spans of the post spacing you type. Posts are spans plus one, then plus extra corners. Rail pieces are spans times rails per span. Estimate only. Gates, slope, and code are not included.
- Grade Calculator Site grade is rise divided by run. You get percent grade, a 1:x ratio, and an angle. This is not a survey plat. Math slope between two points and roof pitch live on other URLs.
- Grass Seed Calculator Seed pounds scale from area and a typed rate. Choose pounds per 1000 square feet or pounds per acre. Soil prep and overseed rates stay on you. Estimate only, not a permit, code check, or engineered design.
- Gravel Calculator Box volume for crushed stone or gravel. Cubic yards divide cubic feet by 27. Optional tons use a density in lb/ft³ you type. This is coverage, not a concrete mix design.
- Insulation Calculator Divide wall or attic area by batt coverage from the label, apply waste from 0 to 40 percent, and round up. R-value and compression stay on you. Estimate only, not a permit, code check, or engineered design.
- Lawn Mowing Calculator Effective cutting width shrinks by overlap percent. Path length is area divided by that width. Time is path length over speed. Estimate only, not a permit, code check, or engineered design.
- Linear Feet Calculator Perimeter mode uses 2 × (length + width). Sum mode adds up to four lengths. Same unit across fields. Estimate only, not a permit, code check, or engineered design.
- Metal Roofing Calculator Panels across ceil from roof length over coverage width. Panels up slope ceil from width over panel length. Waste multiplies the grid. Estimate only, not a permit, code check, or engineered design.
- Metal Weight Calculator Pick a material, a shape, and a length unit. Plate uses length, width, and thickness. Round bar uses length and diameter. Pipe uses length, outside diameter, and wall. Mass is volume times a typical density. Alloys differ. Not a mill cert.
- Mulch Calculator Bed volume for landscaping mulch. Depth is often 2 to 3 inches. Cubic yards divide cubic feet by 27. This is coverage, not a soil test.
- Paint Calculator Wall area is 2 × (length + width) × height. Doors subtract 20 ft² each. Windows subtract 15 ft² each. Gallons are net area times coats divided by coverage, then rounded up to buy. Estimate only.
- Paver Calculator Paved area is length times width. Divide by paver length times paver width, apply waste from 0 to 40 percent, and round up. Borders and patterns change counts. Estimate only, not a permit, code check, or engineered design.
- Pool Volume Calculator A rectangle is length times width times a single depth. A circle is π r² times that depth. Output is cubic meters, liters, and US gallons. Freeform hoppers and spa benches are omitted. Estimate only, not a fill ticket.
- Post Hole Calculator Each hole is π r² h. Multiply by hole count and waste factor. Optional bag yield returns bag count. Default diameter unit is inches and depth unit is feet. Estimate only, not a permit, code check, or engineered design.
- Rebar Calculator Slab length and width are feet. Spacing and edge clearance are inches. Bars form a single mat. Weight uses lb per foot (default 0.668 for #4 class). Estimate only, not a permit, code check, or engineered design.
- Refrigerant Line Charge Calculator Estimate liquid refrigerant mass in a line from length, tube inner diameter, and liquid density. Default 25 ft of 3/8 in OD R-410A tube. Not a charging protocol or EPA procedure.
- Retaining Wall Calculator Wall face area is length times height. Divide by block face, apply waste from 0 to 40 percent, and round up. Optional depth sketches volume. Estimate only, not a permit, code check, or engineered design.
- Roof Area Calculator Plan length times width, then multiply by hypot(run, rise) divided by run. That is a simple gable from a rectangular plan. Estimate only, not a full takeoff.
- Roof Pitch Calculator Pitch is rise over run, shown as x:12, degrees, and percent. The area factor is hypot(1, rise/run). Multiply a plan area by that factor. Estimate only, not code approval.
- Roof Snow Load Calculator Flat-roof sketch pf equals 0.7 times Ce times Ct times I times ground snow pg. Optional roof area multiplies pf into total pounds. Estimate only, not a permit, code check, or engineered design.
- Scale Drawing Calculator Type a length measured on the drawing, a scale like 1:50, the drawing unit, and the real unit. Real length in drawing units is drawn × (right / left). The page also converts into the real unit you pick. Not a survey plat.
- Shingle Calculator Squares with waste equal (area / 100) times (1 + waste/100). Bundles ceil from squares times bundles per square. Default is 3 bundles per square. Estimate only, not a permit, code check, or engineered design.
- Siding Calculator Net wall area subtracts openings. Squares with waste equal (area / 100) times (1 + waste/100). Optional exposure and piece length sketch courses and pieces. Estimate only, not a permit, code check, or engineered design.
- Square Footage Calculator Floor area from rectangles you type. One room uses length and width. Several rooms go in the list, one pair per line. Output is ft², m², acres, and hectares. Estimate only. This is not a survey or code approval.
- Square Inches Calculator Square inches equal length times width when both sides are inches. The page also shows square feet, square centimeters, and square meters. Estimate only, not a permit, code check, or engineered design.
- Stair Calculator Risers are ceil(total rise / max riser), at least 2. Treads equal risers minus 1. Optional total run yields tread depth and 2R+T. This is not building-code approval.
- Stud Calculator Spaces ceil from wall length over on-center spacing. Studs equal spaces plus one, plus extras for corners or openings. Default length unit is feet and spacing unit is inches. Estimate only, not a permit, code check, or engineered design.
- Tank Volume Calculator Vertical cylinder, horizontal cylinder with a circular segment fill, or a rectangular box. Output is m³, liters, and US gallons. The manufacturer stamp wins. This is not a pool-volume calculator.
- Tile Calculator Room area divided by one tile, then waste up to 40 percent, then a whole-tile buy count. Pattern layout can raise waste. Estimate only.
Date and time
- Age Calculator Civil calendar age in the local timezone of this device. Leave As of blank to use today.
- Business Days Calculator Count Monday to Friday between two dates. Optional holidays you type. No public-holiday API.
- Year Calendar Leap flag, weekday of 1 January, ISO week count, and a 12-month table of lengths and start weekdays.
- Date Countdown Days remaining until a date, or days since if the target is past. Also years/months/days.
- Add or Subtract Days Add or subtract years, months, weeks, and days. Month ends clamp (31 Jan + 1 month is 28 or 29 Feb).
- Date Difference Calculator Days between two local calendar dates. If the end is before the start, the result is signed negative.
- Day of Week Calculator Weekday, ISO weekday (Monday = 1), day of year, and leap-year flag.
- Hours Minutes Seconds Calculator Convert duration parts, decimal hours, or total seconds into HH:MM:SS and the other totals.
- Leap Year Calculator Check whether a year is a Gregorian leap year. Divisible by 4, except centuries that are not divisible by 400. The page also reports February length and year length.
- Moon Phase Calculator Approximate phase name, illumination, and age from a civil date using a simple synodic-month model. Not a rise/set almanac and not weather.
- Sunrise Sunset Calculator Sunrise, sunset, and solar noon from latitude, longitude, and date. NOAA solar calculator with zenith 90.833 degrees. Named cities use that city's IANA offset for the date, including DST. Custom uses the minutes you type. Not a weather forecast.
- Time Card Calculator Time card total from in/out lines. Same engine as timesheet, labeled for time-clock searches.
- Time Duration Calculator Add two durations or subtract the second from the first. Hours may go past 24.
- Timesheet Calculator Sum clock-in/out lines into total, regular, and overtime hours. Optional unpaid minutes per line.
- Week Number Calculator ISO-8601 week number and ISO year. Weeks start Monday. Week 1 contains 4 January.
- Work Hours Calculator Net hours for a clock-in/out pair, unpaid break, optional day multiplier, and overtime over a daily threshold.
Everyday
- Aspect Ratio Calculator Width and height reduce by their greatest common divisor. You also get a decimal ratio, landscape or portrait, and optional scale to a target side. This is not crop advice.
- Attendance Calculator Present divided by total sessions is the attendance percent. You also type a minimum percent. The page counts absences used, absences allowed at that minimum, and how many absences remain. This is not a school SIS.
- BTU Heating Calculator Estimate heating load in BTU per hour from floor area, climate preset, and insulation quality. Optional ceiling height reports room volume. Rule of thumb only. Not Manual J.
- Cash Counter Count notes and coins, then the page multiplies each count by a fixed denomination. Pick USD or EUR. The tables are static. This is not a currency converter and not a cash-register certification.
- Recipe Scale Calculator Type original servings, new servings, and one ingredient per line with the amount first. The scale factor is new / original. Only a leading number multiplies. Cups to grams is the cooking converter, not this list scaler.
- Dew Point Calculator Estimate dew point from air temperature in °C and relative humidity. Uses the Magnus-Tetens approximation with a = 17.625 and b = 243.04. Not a weather forecast or HVAC design.
- Download Time Calculator Time to transfer a size at a rate you type. Not a speed test.
- Electricity Cost Calculator Cost equals kilowatt-hours times the rate you type. If kWh is blank, energy is watts times hours times days over 1000. This is not a utility bill.
- EV Charging Cost Calculator Estimate energy needed to charge an EV pack and multiply by your $/kWh rate. Default 75 kWh battery from 20% SOC at $0.15/kWh fills 60 kWh for about $9. Optional trip miles use efficiency. Not a utility bill.
- Fuel Cost Calculator Gallons or liters for a trip, then cost at the price you type. This is not a live station feed and not a fuel unit converter.
- GPA Calculator One course per line: grade and credits, such as A 3 or 3.7 4. Default letters use a 4.0 scale. Your school may differ.
- Final Grade Calculator Score needed on remaining work, or GPA needed on new credits, to hit a target.
- Haversine Distance Calculator Great-circle distance on a sphere of radius 6371.0088 km (IUGG mean). Type two WGS-style latitudes and longitudes in degrees. This is not driving directions, not rhumb line, and not a geodesic on the WGS 84 ellipsoid.
- Heat Index Calculator National Weather Service Rothfusz regression with the published humidity adjustments. Type air temperature in Fahrenheit and relative humidity percent. Below the 80 °F simple-average gate the page uses the Steadham-style average. Not a medical warning product.
- MPG Calculator Fuel economy from a trip distance and the fuel you used. Outputs US mpg, L/100 km, and km/L. This is not a trip cost page.
- Pace Calculator Running or walking pace per km and per mile, plus speed, from distance and time.
- Speed Distance Time Enter exactly two of distance, speed, and time. The third is solved. Pace is listed as well.
- Bill Split Calculator Split a bill, optional tax, and tip across N people in this browser.
- Tip Calculator Tip is bill times percent. Total is bill plus tip. Per person divides the total. Not a local tax table.
- Volumetric Weight Calculator Volumetric weight is box volume in cm³ divided by a divisor you pick. Common air divisors are 5000 or 6000. Optional actual kilograms yield a chargeable mass as the larger of actual and volumetric. Not a carrier quote.
- Wind Chill Calculator National Weather Service 2001 wind chill. Type air temperature in Fahrenheit and wind speed in miles per hour. The formula still prints outside T ≤ 50 °F and wind ≥ 3 mph, with a range note. Not a forecast.
Business
- Break-Even Calculator Units to break even: fixed costs divided by contribution margin per unit.
- Budget Calculator Enter income and category amounts. The page totals allocations, remaining cash, and each category as a percent of income. Informational budgeting arithmetic, not financial advice.
- Straight-Line Depreciation Straight-line depreciation from cost, salvage, and useful life. Not tax-code MACRS.
- Discount Calculator Sale price after a percent off. Informational, not a store coupon.
- Profit Margin Calculator Gross margin, markup, and profit from cost and selling price.
- Markup Calculator Selling price from cost and markup percent.
- Net Effective Rent Calculator Spread free rent or other concessions across the lease term to find net effective monthly rent. Informational landlord math, not legal or financial advice.
- Net Worth Calculator Subtract total liabilities from total assets for a simple net worth snapshot. Informational only, not financial advice and not a balance sheet audit.
- PayPal Fee Calculator Estimate PayPal-style fees as percent plus fixed, either from a payment you receive or from a net you want to keep. You type the fee schedule. Live rates vary. Informational only.
- Prorated Rent Calculator Charge or credit a partial month by multiplying monthly rent by days occupied over days in the month. Informational only, not a lease interpretation.
Income
- Commission Calculator Commission from sales and a single percent. Optional base pay. No tier table in this version.
- Overtime Pay Calculator Regular hours plus overtime hours times a multiplier. Gross only.
- Gross Pay Calculator Gross pay from hours and rate, with optional overtime. No tax withholding tables.
- Salary to Hourly Calculator Gross pay only. Hours per week and weeks per year are yours to set. No tax withholding.
- Take-Home Pay Calculator Net from gross using a tax-and-deduction percent you type. Not a payroll tax table.
Investment
- Annuity Payout Calculator Find the fixed withdrawal that exhausts a starting balance over a set number of years. Choose ordinary or due timing. Figures stay on this device. Informational, not investment advice.
- Annuity Calculator Solve for payment, present value, or future value on a level annuity. Choose end-of-period (ordinary) or beginning-of-period (due). Figures stay on this device. Informational, not investment advice.
- APR to APY Calculator Convert a nominal APR and compounding frequency to APY, or the reverse. Informational, not a product APY.
- Bond Price Calculator Enter face, coupon, yield, years, and coupon frequency. The page discounts remaining cash flows to a clean price sketch. Informational, not investment advice.
- Bond Yield Calculator Type face, coupon rate, market price, and years remaining. Read current yield, approximate YTM, and premium or discount versus face. Informational, not investment advice.
- Bond Calculator Discount coupon cash flows and face value to a clean price sketch. Also shows current yield and a simple approximate YTM. Informational, not investment advice.
- CAGR Calculator Compound annual growth rate between a start value and an end value. Informational, not a forecast.
- Cap Rate Calculator Capitalization rate = NOI / property value. Informational, not an appraisal.
- CD Interest Calculator Certificate of deposit future value at a fixed rate and term you type. Not a bank APY pull.
- College Cost Calculator Grow today's annual college cost by an inflation rate until school starts, then sum each inflated year of attendance. Optional savings rate sketches deposits. Informational, not financial advice.
- Compound Interest Calculator Future value of a lump sum that compounds on a fixed schedule. Figures stay on this device. They are not a forecast or advice.
- Dividend Yield Calculator Type the share price and the annual dividend in the same currency. Yield is annual dividend divided by price. Trailing yield is not a forecast. Informational, not investment advice.
- Future Value Calculator Future value of a lump sum plus an optional payment stream at a fixed rate.
- Inflation Calculator Adjust an amount by an annual inflation rate you type. No live CPI.
- IRR Calculator Internal rate of return: the rate that makes NPV of your cash flows equal zero.
- Mutual Fund Calculator Compound a starting balance at a net return equal to gross return minus expense ratio. Optional deposits each compounding period. Informational, not investment advice.
- NPV Calculator Net present value of a cash-flow list you type. Informational, not a valuation.
- Payback Period Calculator Simple payback = investment / annual cash-in. Optional discounted payback at a rate you type.
- Pension Calculator Estimate annual and monthly pension from years of service, final average salary, and an accrual percent. Optionally discount monthly payments to a lump-sum sketch. Informational, not a plan quote.
- Present Value Calculator Discount a future amount and an optional annuity at a fixed rate.
- Rental Property Calculator Estimate NOI and cap rate from rent, vacancy, and expenses. Optional down payment and mortgage rate sketch debt service and cash-on-cash. Informational, not investment advice.
- 401(k) Projection Calculator Simple 401(k) projection from balance, contribution, optional match, years, and a fixed return. Not tax-aware.
- Retirement Savings Calculator Grow a starting balance with regular contributions at a fixed return, or sketch the nest egg implied by annual spending and a withdrawal rate. Figures stay on this device. Informational, not retirement advice.
- RMD Calculator Divide an account balance by the Uniform Lifetime Table factor for the age you type. Ages 72 to 120. Informational, not tax advice.
- ROI Calculator Return on investment from cost and final value. Informational, not performance reporting.
- Roth IRA Calculator Compound a starting Roth-style balance with optional deposits each period. Contribution limits and tax rules are not enforced. Informational, not tax or investment advice.
- Rule of 72 Calculator Years to double: 72 / rate, plus the exact ln(2)/ln(1+r) comparison.
- Savings Goal Calculator Payment needed each period to reach a future amount at a fixed rate.
- Simple Interest Calculator Simple interest does not add earned interest back to the principal. Figures are informational, not investment advice.
- SIP Calculator Future value of equal periodic contributions at a fixed rate (SIP / recurring investment).
- Traditional IRA Calculator Compound a starting traditional IRA-style balance with optional deposits each period. Deduction and later taxation are not computed. Informational, not tax or investment advice.
Loans
- Amortization Schedule Fixed-rate amortization table: payment, principal, interest, and balance each period. Informational, not a lender quote.
- Auto Lease Calculator Build a monthly lease payment from capitalized cost, residual percent, term, and a money factor or APR. Fees you type add to total cost. Informational, not a dealer quote.
- Car Payment Calculator Auto loan payment from price, down payment, rate, and term. Informational, not a dealer quote.
- Credit Card Interest Calculator Estimate interest for a day count with a simple daily rate. Optional monthly payment can sketch months to pay off. Informational, not lending advice. Issuer methods vary.
- Credit Card Payoff Calculator Months to pay off a revolving balance at a fixed APR and a payment you type.
- Debt Consolidation Calculator Compare staying on the current balance, APR, and payment versus a new rate and term that may include fees. Informational, not lending advice.
- Debt Payoff Calculator Enter up to five balances with APR and minimum payment. Choose avalanche or snowball and an optional extra. Read months, interest, and total paid. Informational, not lending advice.
- Down Payment Calculator Down payment from price and percent, or percent from an amount you type. Optional principal-and-interest estimate.
- EMI Calculator Equated monthly installment on a reducing balance. Informational, not a bank EMI letter.
- Extra Payment Calculator See how extra principal shortens a fixed-rate loan. Informational, not a payoff quote.
- HELOC Calculator From credit limit, drawn balance, and APR, estimate interest-only cost or an amortizing payment. Informational, not lending advice and not a line offer.
- Interest-Only Loan Calculator Interest-only payment = principal times the periodic rate. Principal is due as a balloon at the end of this term.
- Loan Calculator Standard amortization of a fixed-rate loan. Informational, not lending advice.
- How Much House Can I Afford Invert PMT: maximum loan from a target payment, rate, and term. Ignores taxes, insurance, and lender rules unless you type income and DTI.
- Mortgage Calculator Principal and interest for a fixed-rate mortgage. Tax, insurance, and HOA are not included unless you fold them into the amount yourself.
- Refinance Break-Even Calculator Type the current payment, the new payment, and cash closing costs. Months to recoup costs equal costs divided by the monthly savings. Informational, not lending advice and not a quote.
- Rent vs Buy Calculator Stack growing rent payments against mortgage P&I, ownership costs, and an equity sketch after home appreciation. Informational, not lending or investment advice.
Tax
- Estate Tax Calculator Estimate tax as the taxable amount above an exemption times a flat rate you supply. Not a federal or state filing engine. Informational, not tax advice.
- Sales Tax Calculator Add or remove a sales tax rate you type. No jurisdiction table.
- VAT Calculator Net, VAT, and gross from a VAT rate you type. No country table.
Health
- Adjusted Body Weight Calculator Compute Devine ideal body weight and adjusted body weight from sex, height, and total body weight. When total weight is above IBW, ABW = IBW + 0.4 × (TBW - IBW). Informational, not a prescription.
- Army Body Fat Calculator Estimate body-fat percent with the Hodgdon / DoD circumference method, then compare it with an AR 600-9 age-group maximum sketch. Metric tapes convert to inches inside the math. Informational, not an official accession or retention tape.
- BMI Calculator BMI = kg / m². US units convert with 1 lb = 0.45359237 kg and 1 in = 0.0254 m. Informational, not a medical diagnosis.
- BMR Calculator Basal metabolic rate from Mifflin-St Jeor and revised Harris-Benedict. Optional Katch-McArdle if you type body fat. Not medical advice.
- Navy Body Fat Calculator US Navy circumference method. Metric tapes are converted to inches inside the formula. Informational, not an accession tape.
- Body Surface Area Calculator Body surface area from height and weight. Primary formula is Mosteller: sqrt(cm * kg / 3600). Du Bois and Haycock are listed as well. Informational, not medical advice and not a dosing chart.
- Calories Burned Biking Calculator Estimate kilocalories for a bike ride from MET, body weight, and minutes. Choose leisure, moderate, or vigorous cycling intensity. Informational, not a power-meter readout.
- Calories Burned Calculator Estimate how many kilocalories a session burns from MET, body weight, and duration. Pick an activity preset or override MET. Informational, not a lab measurement or medical advice.
- Calories Burned Hiking Calculator Estimate kilocalories for a hike from MET, body weight, and minutes. Choose a standard hike or a steeper / pack-loaded effort. Informational, not a trail prescription.
- Calories Burned Weight Lifting Calculator Estimate kilocalories for a resistance session from MET, body weight, and minutes. Choose vigorous lifting or a lighter circuit. Informational, not a programming coach.
- Calories Burned Running Calculator Estimate kilocalories for a run from MET, body weight, and minutes. Choose easy, typical, or faster pace presets. Informational, not a VO2 lab test.
- Calories Burned Swimming Calculator Estimate kilocalories for a swim from MET, body weight, and minutes. Choose leisure, moderate, or vigorous effort in the water. Informational, not a stroke analysis.
- Calories Burned Walking Calculator Estimate kilocalories for a walk from MET, body weight, and minutes. Choose a casual ~3 mph walk or a brisk ~3.5 mph walk. Informational, not step-count medical advice.
- Carbohydrate Intake Calculator Turn a daily calorie target and a carbohydrate percent into grams using 4 kcal per gram. Default share is 50%. Optional body weight adds a g/kg row. Informational, not a diabetes or diet plan.
- Dog Calorie Calculator Estimate a dog's resting energy requirement (RER) with 70 × kg^0.75, then scale to maintenance energy (MER) using life-stage factors such as neutered adult, puppy, senior, or working. Veterinary rule of thumb, not a substitute for a vet feeding plan.
- Dog Chocolate Toxicity Calculator Sketch theobromine dose in mg/kg from dog weight, chocolate type, and amount eaten. If a dog ate chocolate, contact a veterinarian or pet poison hotline immediately. Do not wait on a web estimate. This page is not a diagnosis or treatment plan.
- Dog Pregnancy Calculator Estimate a whelping date from a breeding (mating) date and a gestation length in days. Default gestation is 63 days; allowed range is 56 to 72. Optional as-of date shows days elapsed and remaining. Breeding-date arithmetic only, not progesterone timing or veterinary care.
- Dog Water Intake Calculator Estimate a healthy dog's daily water volume from body weight and a mL per kilogram rate (default 50). Choose normal or active activity; active multiplies by 1.25. Informational sketch only, not care for polydipsia or illness.
- Fat Intake Calculator Turn a daily calorie target and a fat percent into grams using 9 kcal per gram. Default share is 30%. Informational, not a cholesterol or diet prescription.
- FFMI Calculator FFMI is fat-free mass divided by height squared. Normalized FFMI adjusts that index toward a 1.8 m reference height. Enter height, weight, and a body-fat percent. Informational, not a diagnosis.
- Gestational Age Calculator Gestational age from LMP, estimated due date, and trimester. Same 280-day rule as the due-date page.
- GFR Calculator Estimate glomerular filtration rate with the race-free CKD-EPI creatinine equation (2021). Enter age, sex, and serum creatinine in mg/dL or umol/L. Informational, not a diagnosis of chronic kidney disease.
- Heart Rate Zone Calculator Five zones as percents of estimated max HR. Max HR here is 220 minus age. If you type resting heart rate, zones use Karvonen: rest + percent times (max minus rest). Informational, not medical advice.
- Ideal Weight Calculator Devine, Robinson, Miller, and Hamwi ideal-weight formulas, plus the WHO BMI 18.5 to 24.9 band for that height.
- Lean Body Mass Calculator Lean mass from a body-fat percent you type, or Boer / James / Hume estimates from height, weight, and sex.
- Macro Calculator Split a calorie target into protein, carbohydrate, and fat grams. Protein and carbohydrate use 4 kcal per gram. Fat uses 9 kcal per gram. Percents must sum to 100. Informational, not medical advice and not a diet plan.
- One Rep Max Calculator Estimate a one-repetition maximum from a submaximal set. Enter the weight you lifted and how many clean reps you completed (2 to 12). The page shows Epley, Brzycki, Lander, Lombardi, Mayhew, and their average. Informational, not a training prescription.
- Ovulation Calculator Estimate ovulation as cycle start plus (cycle length minus 14 days). Also lists a simple fertile window and the next period if the cycle stays constant. Informational, not medical advice. Not contraception.
- Pregnancy Conception Calculator Estimate a conception date and a short fertile window from either a due date or a last menstrual period. Rules use LMP + 14 days or due date minus 266 days. Calendar sketch only, not obstetric ultrasound dating.
- Due Date Calculator Estimated due date as LMP + 280 days (Naegele), with gestational age and trimester. Not obstetric care.
- Pregnancy Weight Gain Calculator Map pre-pregnancy height and weight to IOM gestational weight-gain ranges. Choose singleton or twins tables and optionally compare a gain in pounds. Informational, not prenatal care or medical advice.
- Protein Intake Calculator Estimate a daily protein target in grams from body weight and a goal band. Bands cover sedentary, active, strength, athlete, and older-adult ranges. Optionally override grams per kilogram. Informational, not a medical diet.
- Sleep Cycle Calculator Suggest bedtimes from a wake time, or wake times from a bedtime, using repeating cycle blocks (default 90 minutes) plus a fall-asleep buffer (default 14 minutes). Shows 6, 5, 4, and 3 cycle options. Informational sketch, not a medical sleep study.
- TDEE Calculator TDEE = Mifflin-St Jeor BMR × activity factor. All five common factors are listed. Not a diet prescription.
- Waist to Hip Ratio Calculator WHR = waist / hip using the same length unit on both tapes. WHO adult labels differ by sex. Informational, not medical advice and not a diagnosis.
- Water Intake Calculator Estimate a daily water volume from body weight, activity level, climate, and a base mL per kilogram rate (default 33). Results appear in liters, milliliters, and US fluid ounces. Informational, not medical advice for illness or kidney disease.
Math
- Adding Machine Running total of a list: sum, count, and mean. Negatives allowed as subtractions.
- Binary Math Calculator Integer binary math and bitwise ops. Output in decimal, binary, hex, and octal. Stays in this tab.
- Combination Calculator C(n, k) = n! / (k! (n − k)!) for unordered selections.
- Decimal to Fraction Calculator Best-fit fraction for a decimal, searching denominators up to the cap you set.
- Distance Between Two Points Euclidean distance between two plane points.
- Equation of a Line Calculator Enter two distinct plane points. The page returns slope m, y-intercept b, slope-intercept form y = mx + b, and point-slope form through the first point. Vertical segments report x = constant instead.
- Euclidean Algorithm Calculator Compute gcd(a, b) by repeating a = bq + r until the remainder is 0. The page lists each division step so you can check homework against the classic Euclidean algorithm. Defaults are a = 1071 and b = 462.
- Exponent Calculator base^exponent with IEEE floating point. Rejects non-finite results.
- Factorial Calculator n! for an integer from 0 to 170. 0! is 1.
- Fibonacci Sequence Calculator Build the classic Fibonacci list starting at F0 = 0 and F1 = 1. Enter how many terms you want (up to 78 so every value stays a safe integer). The page lists the full sequence and highlights the last term.
- Fraction to Decimal Calculator Divide a fraction to a decimal and show the simplified form.
- Fraction Calculator Add, subtract, multiply, or divide two fractions. Result is simplified, mixed, and decimal.
- GCD Calculator Greatest common divisor of two or more integers, Euclidean algorithm.
- Increase or Decrease by Percent Increase or decrease a number by a percent. Returns the new amount and the difference.
- LCM Calculator Least common multiple of two or more integers. Rejects results beyond safe integers.
- Logarithm Calculator log_base(value), plus ln and log10 of the same value. Value must be positive.
- Long Division Calculator Integer division with quotient, remainder, and a reconstruction check. Truncates toward zero.
- Matrix Calculator Work with square 2x2 or 3x3 matrices only. Choose determinant, add, subtract, multiply, or inverse. Type each row as numbers separated by spaces, and separate rows with semicolons. This is numeric linear algebra for small matrices, not a computer algebra system (CAS).
- Midpoint Calculator The midpoint of a plane segment is the average of the endpoints. Type x1, y1, x2, and y2. Distance and slope of the same segment live on other math pages.
- Mixed Number Calculator Convert mixed numbers to improper fractions and back, then simplify.
- Modulo Calculator Type integers a and n. The page shows a Euclidean remainder (non-negative when n is positive), the JavaScript remainder a % n that follows the sign of a, and a floored remainder. n cannot be 0.
- Nth Root Calculator Principal real nth root. Even roots of negatives are rejected. n cannot be 0.
- Order of Operations Calculator Evaluate an arithmetic expression with ^ as power, * / before + −, and parentheses. Same parser as the scientific calculator.
- Percent Yield Calculator Compute percent yield from actual and theoretical yields. Both yields must use the same unit (grams or moles). Formula: % yield = (actual / theoretical) × 100.
- Percentage Change Calculator Percent change from an original value to a new value, plus the raw difference.
- What Is P Percent of X What is P percent of X. Same arithmetic as the percentage hub, locked to this job.
- Percentage to Fraction Convert a percent to a simplified fraction, mixed number, and decimal.
- Percentage Calculator Everyday percentage jobs: of, what percent, change, increase, and decrease. Figures stay on this device.
- Permutation Calculator P(n, k) = n! / (n − k)! for ordered selections. n at most 170 on this page.
- Price Elasticity Calculator Compute price elasticity of demand from two prices and two quantities. Choose midpoint (arc) elasticity or simple percent change from the initial values. Informational, not pricing advice.
- Prime Factorization Prime factorization of an integer from 2 to 1,000,000,000,000.
- Prime Checker Trial-division primality for integers up to 1,000,000,000,000 in absolute value.
- Proportion Calculator Solve a/b = c/d. Leave exactly one of a, b, c, d blank.
- Quadratic Formula Calculator Roots of ax² + bx + c = 0, including complex roots when the discriminant is negative.
- Ratio Calculator Simplify a:b and optionally solve a:b = c:x.
- Rounding Calculator Pick a rounding kind and a digit count. Half up, half down, and half even disagree on ties. Floor and ceil step toward -infinity or +infinity. Significant figures use the digits field as the significant count.
- Scientific Calculator Type an expression or use the keypad. Trigonometry uses the angle mode you pick. Nothing is uploaded.
- Slope Calculator Slope, y-intercept, line equation, and distance between two points. Vertical lines are flagged.
- Square Root Calculator Principal square root. Negatives are rejected as non-real on this page.
- Standard Form Calculator Convert any finite number into standard form a × 10^n, where the coefficient satisfies 1 ≤ |a| and |a| is less than 10 when the value is non-zero. Enter 12300 to see 1.23 × 10^4. Zero maps to 0 × 10^0.
- Vector Addition Calculator Add or subtract vectors a and b by matching components. Choose the operation, enter ax through bz, and read the result triple plus its Euclidean magnitude.
- Vector Magnitude Calculator Find the Euclidean length of a vector from components x, y, and optional z. Nonzero vectors also return the unit vector in the same direction.
- What Percent Is X of Y What percent is A of B. Whole cannot be 0.
- X and Y Intercepts Calculator Choose slope-intercept form or standard form. The page returns where the line meets the axes. Horizontal lines have no x-intercept. Vertical lines have no y-intercept.
Geometry
- Circle Calculator Radius, diameter, circumference, and area. Enter any one; the rest follow with π from this device.
- Circumference to Diameter Calculator Enter exactly one of circumference, diameter, or radius. The page fills the other two using Math.PI from this browser. Area is not on this spoke; use the circle calculator for area.
- Cone Calculator Right circular cone. Volume is one third π r squared h. Slant height is the hypotenuse of r and h. Lateral and total surface follow from that slant. Units are whatever you typed.
- Cylinder Calculator Right circular cylinder: volume, lateral area, and total surface area.
- Ellipse Calculator Enter semi-axes a and b. Area is exactly πab. Perimeter uses Ramanujan's closed-form approximation, not an elliptic-integral solver.
- Heron's Formula Calculator Find the area of any triangle when you know all three sides. Heron's formula uses the semi-perimeter s = (a + b + c) / 2, then area = sqrt(s(s - a)(s - b)(s - c)). Defaults show the classic 3-4-5 right triangle.
- Parallelogram Area Calculator Compute parallelogram area from base and perpendicular height. Enter the adjacent side when you also want perimeter. Area uses A = base × height, not the slanted side alone.
- Regular Polygon Area Calculator Compute area, perimeter, circumradius, and apothem for a regular polygon. Enter integer side count n and equal side length s. Irregular polygons are out of scope.
- Pythagorean Theorem Calculator Solve a² + b² = c². Enter exactly two of a, b, and c.
- Rectangle Calculator Rectangle area, perimeter, and diagonal. A square is the case length = width.
- Sphere Calculator Sphere volume and surface area from radius.
- Trapezoid Area Calculator Enter the two parallel bases and the perpendicular height. Area uses ((a + b) / 2) × h. Add both non-parallel legs when you also want perimeter.
- Triangle Calculator SSS triangle: Heron area, perimeter, all three angles, side class, and acute/right/obtuse.
Statistics
- Bayes Theorem Calculator Update a prior with evidence. Enter P(A), P(B|A), and P(B) to get the posterior P(A|B) = P(B|A) P(A) / P(B).
- Binomial Probability Calculator Exact P(X = k), P(X ≤ k), and P(X ≥ k) for a binomial experiment with n trials, success probability p, and k successes. n is capped at 1000 on this page.
- Confidence Interval Calculator Build a normal (z) confidence interval for a mean from sample mean, SD, sample size, and a common confidence level. Educational large-n form, not a Student-t table product.
- Correlation Calculator Pearson product-moment r for paired numbers. Type one x y pair per line. r sits between -1 and 1. This is not Spearman rank or a p-value table.
- Average Calculator Arithmetic mean, sum, count, min, max, and range of a list you type.
- Median and Mode Median and mode of a numeric list. Ties for mode are listed together.
- Probability Calculator Combine two probabilities with and, or, not, or conditional rules. Toggle independence or type P(A and B) when events depend on each other.
- Sample Size Calculator Wald sample size for a proportion. n = z^2 p (1-p) / e^2. Optional finite N. Educational, not a survey product and not a power analysis for a mean.
- Standard Deviation Calculator Population and sample standard deviation and variance for a list you type.
- t-Score Calculator Compute the one-sample t statistic from a value x, hypothesized or sample mean, sample SD s, and sample size n. Educational arithmetic only; no critical-value table.
- Variance Calculator Population and sample variance, with matching standard deviations.
- Weighted Average Weighted average from value-weight pairs. Weights must sum to more than 0.
- Z-Score Calculator z = (x − mean) / SD. Standard deviation cannot be 0.
Science
- Amps to Kilowatts Calculator Current from kilowatts and volts. DC uses I = P / V. Single-phase divides by PF. Three-phase divides by root 3 times V times PF. Informational, not wiring or code approval.
- Amps to kVA Calculator Find apparent kVA from line current and voltage. Single-phase kVA = V × I / 1000. Default 20 A at 240 V gives 4.8 kVA. Informational only.
- Amps to Volt-Amps Calculator Find apparent volt-amperes from current and voltage. Single-phase VA = V × I. Default 15 A at 120 V gives 1800 VA. Informational only.
- Atoms to Moles Calculator Convert a particle count to moles, or moles to particles, using the SI Avogadro constant NA = 6.02214076×10²³ mol⁻¹. Works for atoms, molecules, or formula units.
- Capacitance to Charge Calculator Convert capacitance and voltage to stored charge Q = C × V. Default 100 µF at 12 V gives 0.0012 C (1200 µC). Informational only.
- Coulomb's Law Calculator Compute electrostatic force between two point charges: F = k |q1 q2| / r². Default 1 µC and 1 µC at 0.1 m separation. Uses k = 8.9875517923×10⁹ N·m²/C². Informational physics only.
- dBm to Watts Calculator Convert dBm to watts with P_W = 10^((dBm - 30) / 10). 0 dBm equals 1 mW. Informational, not an RF license or wiring approval.
- Density Calculator Density is mass divided by volume. You get kg/m³, g/cm³, and lb/ft³. This is informational. Density equals specific gravity only when you compare to water at a stated temperature.
- Molarity Dilution Calculator Solve one unknown in C1V1 = C2V2 when concentrations are molarities (mol/L) or any matching concentration unit. Leave exactly one of C1, V1, C2, V2 blank. Not a lab protocol.
- Dilution Calculator Solve one unknown from C1V1 = C2V2. Use the same concentration unit on C1 and C2, and the same volume unit on V1 and V2. Not a lab protocol. Informational, not chemical safety or code approval.
- Ideal Gas Moles Solver Solve the amount of gas n from PV = nRT, or solve pressure, volume, or temperature instead. Defaults target moles. R = 8.314462618 J/(mol·K). Informational, not a pressure-vessel rating.
- Gear Ratio Calculator Ratio = driven teeth / driver teeth. Optional input RPM gives output RPM as input RPM / ratio. Informational, not a gearbox rating or code approval.
- Half-Life Calculator Exponential decay for a single species. Leave exactly one of half-life, elapsed time, initial amount, and remaining amount blank so the page can solve it. Not medical or radiological guidance.
- Hooke's Law Calculator Linear spring force F = k x. Default k = 100 N/m and x = 0.01 m gives 1 N. Informational, not a spring rating, wiring approval, or code approval.
- Ideal Gas Law Calculator Solve one of pressure, volume, amount, or temperature from PV = nRT. R is 8.314462618 J/(mol K). Informational, not a pressure-vessel rating, wiring approval, or lab protocol.
- Joules to Watts Calculator Find average power from energy and time: P = E / t. Default 3600 J over 3600 s gives 1 W. Informational only.
- Kinetic Energy Calculator Translational kinetic energy KE = 1/2 m v squared. Mass in kilograms, speed in meters per second, energy in joules. Informational, not a safety rating or code approval.
- kVA to Amps Calculator Convert apparent kVA to line current with voltage. Single-phase: I = kVA × 1000 / V. Three-phase includes √3. Default 5 kVA at 240 V single-phase is about 20.833 A. Informational only.
- kVA to kW Calculator Find real kilowatts from apparent kVA: kW = kVA × PF. Default 10 kVA at PF 0.85 gives 8.5 kW. Informational only.
- kVA to Watts Calculator Convert apparent kVA to real watts: W = kVA × PF × 1000. Default 3 kVA at PF 0.9 gives 2700 W. Informational only.
- kW to kVA Calculator Convert real power in kilowatts to apparent power in kVA: kVA = kW / PF. Default 5 kW at power factor 0.9 gives 5.556 kVA. Informational only.
- LED Resistor Calculator Series resistor R = (Vs - Vf) / I for one LED on DC. Informational, not a driver design or wiring approval.
- Molality Calculator Solve moles of solute, kilograms of solvent, or molality using m = n / kg solvent. Molality stays stable when temperature changes volume. Informational, not a lab protocol.
- Molar Mass Calculator Type a chemical formula to get molar mass in g/mol. The page parses element symbols and parentheses, then sums IUPAC typical atomic weights. Also called molecular weight for covalent compounds.
- Molarity Calculator Solve any one of moles of solute, solution volume, or molarity using M = n / V. Volume is the total solution volume. Informational, not a lab protocol or chemical safety guide.
- Moles to Grams Calculator Convert moles to grams or grams to moles. Type a molar mass in g/mol, or enter a formula such as H2O so the page sums atomic weights first. Formula: n = m / M.
- Ohm's Law Calculator Solve volts, amps, ohms, and watts from any two of V, I, and R, or from power plus one of those. Informational, not wiring or code approval.
- Parallel Plate Capacitance Calculator Estimate capacitance of parallel plates: C = ε0 εr A / d. Default 0.01 m² area, 1 mm separation, εr = 1 uses vacuum permittivity. Informational lab math only.
- Parallel Resistance Calculator Find equivalent resistance for parallel branches. 1/Rtotal = 1/R1 + 1/R2 + ... + Rn. Three 100 Ω resistors in parallel give 33.333 Ω. Informational only.
- Peak-to-Peak Voltage Calculator Convert RMS or peak voltage to peak-to-peak on a sine. Vpp = 2 × Vpeak = 2√2 × Vrms. Default 120 V RMS gives about 339.4 V peak-to-peak. Informational only.
- Peak Voltage Calculator Find peak voltage from RMS or peak-to-peak on a sinusoidal wave. Vpeak = Vrms × √2. The default 120 V RMS is about 169.7 V peak. Informational, not wiring approval.
- RC Time Constant Calculator Compute τ = R × C for a resistor-capacitor pair. Default 1000 Ω and 10 µF gives τ = 0.01 s. The page also shows 5τ, about 99.3% of full charge on an ideal step. Informational only.
- Resistor Color Code Calculator Read 4-band and 5-band resistor values from IEC 60062 colors. Informational, not a wattage rating or wiring approval.
- RMS Voltage Calculator Convert peak or peak-to-peak voltage to RMS for a sinusoidal wave. Vrms = Vpeak / √2. The default 170 V peak matches a 120 V RMS household sine. Informational, not wiring approval.
- RPM Calculator Surface speed from diameter and RPM: v = pi d n / 60, with n in revolutions per minute. Enter exactly two of diameter, RPM, and speed. Informational, not a machine rating or code approval.
- Series Resistance Calculator Add resistances in series. Rtotal = R1 + R2 + ... + Rn. Default list 100, 220, 330 Ω sums to 650 Ω. Informational, not a BOM checker.
- VA to kW Calculator Convert volt-amperes to real kilowatts: kW = VA × PF / 1000. Default 5000 VA at PF 0.88 gives 4.4 kW. Informational only.
- Volt-Amps to Amps Calculator Convert volt-amperes to current: I = VA / V on single-phase. Default 1800 VA at 120 V gives 15 A. Informational only.
- Voltage Divider Calculator Unloaded divider Vout = Vin times R2 / (R1 + R2). Informational, not wiring or code approval.
- Voltage Drop Calculator Conductor voltage drop at 20 °C. Informational, not a code table.
- Watts to Amps Calculator Current from power and voltage. Informational, not wiring advice.
- Watts to Joules Calculator Convert power over time to energy: E = P × t. Default 100 W for 60 seconds gives 6000 J (6 kJ). Informational physics and billing prep only.
- Watts to kVA Calculator Convert real watts to apparent kVA: kVA = (W / 1000) / PF. Default 2400 W at PF 0.9 gives 2.667 kVA. Informational only.
- Wavelength Frequency Calculator Solve c = f lambda. Default wave speed is 299792458 m/s, the speed of light in vacuum. Enter frequency or wavelength. Informational, not a radio license or wiring approval.
- Wire Ampacity Calculator Look up NEC 310.16 style ampacity by AWG, material, and temperature column. Default 12 AWG copper at 75 °C uses the table ampacity with optional derating. Informational, not code approval.
Calculator questions
Does a calculator upload my numbers?
No. The formula runs in the page you opened. CZNull does not receive the values.
Is the result a quote I can take to a bank?
No. Rounding, day counts, fees, and tax in the real world can differ. Use the page to check the arithmetic.