One-rep max calculator
Enter the weight and reps from a hard set. The calculator estimates the most you could lift once.
Updated October 2026
Estimated one-rep max
208.1 lb
Weight for each rep count
| Reps | % of max | Weight |
|---|---|---|
| 1 | 100% | 208.1 lb |
| 2 | 97.2% | 202.3 lb |
| 3 | 94.4% | 196.6 lb |
| 5 | 88.9% | 185 lb |
| 8 | 80.6% | 167.7 lb |
| 10 | 75% | 156.1 lb |
| 12 | 71.4% | 148.7 lb |
Other formulas
| Formula | Estimate |
|---|---|
| Epley | 215.8 lb |
| Brzycki | 208.1 lb |
| Lombardi | 217.3 lb |
| O'Conner | 208.1 lb |
| Mayhew | 220.2 lb |
| Wathan | 215.7 lb |
How the estimate works
Every formula turns reps into a multiplier on the weight. The more reps in the set, the larger the multiplier, and the less certain the result. These are the formulas this calculator shows.
| Formula | Calculation |
|---|---|
| Epley | weight × (1 + reps ÷ 30) |
| Brzycki | weight × 36 ÷ (37 − reps) |
| Lombardi | weight × reps^0.10 |
| O'Conner | weight × (1 + 0.025 × reps) |
| Mayhew | weight × 100 ÷ (52.2 + 41.9 × e^(−0.055 × reps)) |
| Wathan | weight × 100 ÷ (48.8 + 53.8 × e^(−0.075 × reps)) |
What percent of your max is each rep count?
If you can lift a weight for this many reps, it is about this share of your one-rep max. Use it to pick a training weight from your max.
| Reps | % of one-rep max |
|---|---|
| 1 | 100% |
| 2 | 97.2% |
| 3 | 94.4% |
| 4 | 91.7% |
| 5 | 88.9% |
| 6 | 86.1% |
| 8 | 80.6% |
| 10 | 75% |
| 12 | 71.4% |
One-rep max by lift
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Questions
How do you calculate a one-rep max?
Multiply the weight you lifted by a factor that grows with the reps. The Epley formula is weight × (1 + reps ÷ 30). The Brzycki formula is weight × 36 ÷ (37 − reps). For 5 reps at 185 lb, Epley gives 216 lb and Brzycki gives 208 lb.
Which one-rep max formula is the most accurate?
None is exact. Brzycki is a good fit up to about 10 reps. Epley is a good fit above that, because Brzycki rises too quickly past 10 reps. The Lift app uses Brzycki up to 10 reps and Epley above, and the two agree at exactly 10 reps.
How many reps should I use to estimate my max?
Use a hard set of 2 to 6 reps. Fewer reps means a smaller gap between what you lifted and your max, so the estimate is tighter. Sets of more than 10 reps give a loose estimate, because stamina starts to matter as much as strength.
Is the calculator the same for squat, bench press and deadlift?
The maths is the same. The result is not equally accurate: it tends to be best for the bench press and squat and looser for the deadlift, where grip and back position change over a set.
Should I test my real one-rep max?
Most people do not need to. An estimate from a hard set of a few reps is safer, and it is good enough to choose training weights. If you do test a max, use safety arms or a spotter.
More free tools
Lift does this maths for you
Lift is a strength log for iPhone. It fills in every set with the weight and reps that beat last time, works out your warm-ups, and tracks your estimated one-rep max for every lift. It is coming soon to the App Store.
About Lift