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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.

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Results

How to calculate miles per gallon

  1. Enter the distance you drove and pick miles or kilometers.
  2. Enter fuel used in US gallons or liters. Do not enter hours. Time is not an input.
  3. Read US mpg, liters per 100 km, and km per liter.
  4. UK mpg is about 1.20095 times US mpg for the same burn. Nothing is uploaded.

Fuel economy

Distance divided by fuel volume

US mpgmiles / US gallons
L/100 km235.214583 / US mpg
km/Lkilometers / liters
US gallon3.785411784 liters
UK mpgAbout 1.20095 × US mpg
Not computedHours, speed, or trip cost

How mpg, L/100 km, and km/L relate

Miles over US gallons is US mpg. L/100 km is 235.214583 divided by that mpg. Kilometers over liters is km/L. Liters convert with 3.785411784 L per US gallon. The page never asks for time.

US mpg versus UK mpg

The imperial gallon is larger, so UK mpg reads higher for the same economy. Multiply US mpg by about 1.20095 for a UK mpg estimate. Cost of the fill lives on the fuel cost calculator.

Use cases

Checking a tank fill against the dash average, converting a US mpg sticker to L/100 km, or logging a loop in kilometers with liters. Traffic and idle are already inside the fuel you typed.

Limits

Distance and fuel used must be greater than 0. This is not a live telematics feed. CZNull does not receive the numbers.

MPG calculator questions

Does this page upload my numbers?
No. The formula runs in the page you opened. CZNull does not receive the values.
Why is there no hours field?
Economy here is distance over fuel. Time belongs on pace or speed-distance-time.
US mpg or UK mpg?
The main row is US mpg. UK mpg is about 1.20095 times that number because the imperial gallon is larger.
How do I get L/100 km?
The page reports it from the same fill. Lower L/100 km is better economy.
Is trip cost included?
No. Open the fuel cost calculator and type a price.
Can I treat the result as official?
No. Pump calibration and dash rounding can differ. Use the page to check the arithmetic.