One Rep Max Calculator
Estimate your one-rep max from any weight-and-reps set with Epley and Brzycki formulas, plus a 1–12 rep training table with percentages of 1RM.
| Reps | Max weight | % of 1RM |
|---|---|---|
| 1 | 112.9 kg | 96.8% |
| 2 | 109.4 kg | 93.8% |
| 3 | 106.1 kg | 90.9% |
| 4 | 102.9 kg | 88.2% |
| 5 | 100 kg | 85.7% |
| 6 | 97.2 kg | 83.3% |
| 7 | 94.6 kg | 81.1% |
| 8 | 92.1 kg | 78.9% |
| 9 | 89.7 kg | 76.9% |
| 10 | 87.5 kg | 75% |
| 11 | 85.4 kg | 73.2% |
| 12 | 83.3 kg | 71.4% |
Both formulas are estimates from submaximal sets. They agree best in the 4–10 rep range; above ~10 reps fatigue makes predictions drift, and nothing beats actually testing the lift.
This tool runs entirely in your browser. Your data never leaves your device — it is not uploaded to any server.
How to use
- 1Enter the weight you lifted and choose kg or lb.
- 2Enter the number of reps you completed with good form.
- 3Read the Epley and Brzycki estimates and the 1–12 rep training table underneath.
One Rep Max Calculator
Enter a weight you lifted and how many clean reps you completed, and get your estimated one-rep max (1RM) from two established formulas: Epley's w × (1 + reps/30) and Brzycki's w × 36/(37 − reps). At 225 lb × 10 both land on exactly 300 lb, which is why that set is a gym classic.
Below the estimate, a training table converts your 1RM into working weights: the heaviest load you can expect to lift for each rep count from 1 to 12, with its percentage of 1RM — the percentages coaches use to program strength, hypertrophy and endurance blocks.
Frequently asked questions
Which formula should I trust?
Both are estimates from submaximal sets, and both are most accurate between about 4 and 10 reps. Epley (1976) runs slightly optimistic at low rep counts; Brzycki (1993) runs slightly conservative. The usual practice is to treat the two numbers as a bracket: if they agree within a few kilograms, you have a reliable 1RM estimate.
Why does the table show 75% of 1RM for 10 reps?
The percentages come from inverting the Epley equation: the most you can lift for n reps is roughly 1RM × 30/(30 + n). Ten reps works out to 75%, five reps to about 86%. Real percentages drift with the lift (squats tolerate more reps than presses) and with your fiber makeup, so treat the table as a starting point for programming.
Why can't I enter more than 20 reps?
Because the formulas stop meaning anything there. Past ~12 reps the result is dominated by local endurance rather than strength, and Brzycki's denominator (37 − reps) collapses toward zero. High-rep sets measure conditioning; if you want a max estimate from them, use a lighter-weight formula designed for endurance work.
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