One Rep Max Calculator
Your estimated 1RM by Epley and by Brzycki, from one set, with training percentages.
- Epley
- 116.7 kg
- Brzycki
- 112.5 kg
Epley reads 4.2 kg (3.7%) higher.
| % of 1RM | Epley | Brzycki |
|---|---|---|
| 100% | 116.7 kg | 112.5 kg |
| 95% | 110.8 kg | 106.9 kg |
| 90% | 105 kg | 101.3 kg |
| 85% | 99.2 kg | 95.6 kg |
| 80% | 93.3 kg | 90 kg |
| 75% | 87.5 kg | 84.4 kg |
| 70% | 81.7 kg | 78.8 kg |
| 65% | 75.8 kg | 73.1 kg |
| 60% | 70 kg | 67.5 kg |
| 55% | 64.2 kg | 61.9 kg |
| 50% | 58.3 kg | 56.3 kg |
| Reps | Epley | Brzycki |
|---|---|---|
| 1 | 116.7 kg | 112.5 kg |
| 2 | 109.4 kg | 109.4 kg |
| 3 | 106.1 kg | 106.3 kg |
| 4 | 102.9 kg | 103.1 kg |
| 5 (your set) | 100 kg | 100 kg |
| 6 | 97.2 kg | 96.9 kg |
| 7 | 94.6 kg | 93.8 kg |
| 8 | 92.1 kg | 90.6 kg |
| 9 | 89.7 kg | 87.5 kg |
| 10 | 87.5 kg | 84.4 kg |
| 11 | 85.4 kg | 81.3 kg |
| 12 | 83.3 kg | 78.1 kg |
Your one-rep max (1RM) is the most you can lift once, with good form. Testing it directly is tiring and, without a spotter, risky, so most lifters estimate it from a set they have already done: a weight and how many reps it took to reach failure. This calculator gives that estimate by the two formulas most calculators use, side by side, because they disagree and neither one is the right answer.
The two formulas
Epley multiplies the weight by 1 + reps / 30. Brzycki multiplies it by 36 / (37 − reps). Both are named after the strength coaches who published them. A single is its own max in both: Epley's formula on its own would add 3.3% to a one-rep set, so this calculator reports the weight itself.
They agree exactly at 10 reps. Below that, Epley reads higher: 3.7% to 3.9% higher for sets of 2 to 5 reps. Above 10, Brzycki reads higher, and it climbs quickly. At 12 reps of 100 kg, Epley says 140 kg and Brzycki 144 kg; at 20 reps, 166.7 kg against 211.8 kg. Brzycki's formula has no answer at all at 37 reps, where it divides by zero, so the calculator shows only Epley there.
A worked example
A set of 5 at 100 kg, the figures this page opens with, gives 116.7 kg by Epley and 112.5 kg by Brzycki, a gap of 4.2 kg or 3.7%. Running each formula backwards from its own 1RM gives the rep maxes: 106.1 or 106.3 kg for 3 reps, and 87.5 or 84.4 kg for 10. The row for 5 reps gives back 100 kg by both, which is the set you entered.
Using the tables
Training programs are often written as a percentage of your 1RM: "5 sets of 5 at 80%". The percentage table turns those into weights for each formula's estimate. The rep-max table answers the other common question: if this is my 1RM, what should I manage for 8 reps? If the two columns differ by more than your smallest plate, start from the lower one.
The unit switch only changes the label. Both formulas multiply the weight by a factor that depends on reps alone, so pounds in give pounds out, with the same ratios.
Which one-rep max formula is most accurate?
Neither is right for everyone. How many reps you can do at a given percentage of your max varies from lifter to lifter and from lift to lift, so the honest answer is a range. Seeing both formulas shows how wide that range is for your set.
Why does another calculator give me a different 1RM?
It may use one formula, the other, or a blend of them. For sets of 2 to 5 reps, Epley reads 3.7% to 3.9% above Brzycki, so the same set can come out several kilograms apart.
How many reps should my test set be?
Fewer reps give a closer estimate, because the formulas have less distance to extrapolate. Above 12 reps the two formulas part ways quickly, and at 20 reps they are over 20% apart.
Does the weight unit change the result?
No. Both formulas scale the weight by a factor that depends only on reps, so the estimate comes out in whatever unit you entered.