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.
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How to estimate one-rep max
- Choose kilograms or pounds so the output unit matches your gym plates.
- Enter the weight you lifted for a clean set without failed reps.
- Enter how many reps you completed. This page accepts 1 through 12.
- Read the average estimate plus each named formula. Use the range as a sketch, not a mandate.
- Pair with the weight-lifting calorie page only if you also want session energy. Nothing is uploaded.
One-repetition maximum
Estimated max load from submaximal reps
| Epley | w × (1 + reps/30) |
|---|---|
| Brzycki | w × 36 / (37 - reps) |
| Other formulas | Lander, Lombardi, Mayhew |
| Rep range | 1 to 12 on this page |
| Output | Per-formula 1RM plus average |
| Advice | Informational. Not a programming coach. |
What a 1RM estimate is
A one-rep max is the heaviest load you could lift once with good form. Testing it directly is hard, so coaches often invert a multi-rep set through published equations. This page runs five common equations and averages them so you see agreement and spread.
How the formulas differ
Epley grows linearly with reps. Brzycki divides by (37 - reps) and becomes unstable near 37 reps, which is why this page caps at 12. Lander, Lombardi, and Mayhew use other curves fitted to lifting data. At one completed rep the page returns the weight itself and skips curve math.
Load, reps, intensity, and related jobs
Entities include bar weight, repetition count, estimated 1RM, and relative intensity. Session calorie burn from MET tables is on calories burned weight lifting. Body-mass context without strength formulas is BMI.
Use cases
Turning a 5-rep squat into a working max for percentage-based programs. Cross-checking that two formulas do not disagree wildly before you set training loads. Not for failed grinders, partial reps, or machine cams that distort free-weight curves.
Default numbers
100 kg for 5 reps yields about 116.7 kg on Epley and 112.5 kg on Brzycki. The average of all five formulas sits near 116 kg. Treat that band as a planning sketch.
Limits
Formulas were fitted on specific lifts and populations. High-rep endurance sets and technical Olympic lifts fit poorly. Caps at 12 reps. Informational only. See the disclaimer.