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1RM calculator
Enter a set you actually did. You get three estimated one-rep maxes, their average, and a percentage table rounded to loads you can put on the bar.
Calculator
Estimated 1RM (average)
115.5kg
- Epley
- 116.7
- Brzycki
- 112.5
- Lombardi
- 117.5
Above 10 reps the formulas disagree a lot. Treat this as a rough guide.
| % of 1RM | Load | Reps (approx.) |
|---|---|---|
| 100% | 115 kg | 1 |
| 95% | 110 kg | ~2 |
| 90% | 105 kg | ~3 |
| 85% | 97.5 kg | ~5 |
| 80% | 92.5 kg | ~8 |
| 75% | 87.5 kg | ~10 |
| 70% | 80 kg | ~13 |
| 65% | 75 kg | ~16 |
| 60% | 70 kg | ~20 |
| 55% | 62.5 kg | ~25 |
| 50% | 57.5 kg | ~30 |
How the three formulas work
Each formula turns a set of several reps into an estimate of the most you could lift once. Here w is the load and r the reps you completed:
| Formula | Equation | 100 kg × 5 |
|---|---|---|
| Epley (1985) | w × (1 + r / 30) | 116.7 |
| Brzycki (1993) | w × 36 / (37 − r) | 112.5 |
| Lombardi (1989) | w × r0.10 | 117.5 |
At low reps they land within a few percent of each other. They split as reps climb: Brzycki is the lowest from 2 to 9 reps, equals Epley at 10, then rises fastest. Lombardi is the most conservative from about 8 reps up. For a single, all three simply return the weight you lifted.
Getting a useful estimate
- Use a hard set. The math assumes the set was close to failure. A set of 5 with 3 reps left in the tank underestimates you. Log RPE or reps in reserve and the RPE chart can correct for it.
- Stay at about 3 to 6 reps. Prediction error grows with rep count, and it varies by lift and lifter.
- Track the trend, not the number. Use the same formula every week. A rising e1RM from your top sets is good evidence of progress, even without testing a max.
The rep counts in the table come from the Epley curve and are only a starting point. More detail, with sources, is in 1RM formulas explained.
Questions
Which 1RM formula is the most accurate?
None is best for everyone. All three agree closely for sets of about 2 to 6 reps and drift apart above 10. Accuracy also depends on the exercise and on how close to failure the set really was, so use sets of about 3 to 6 hard reps and track the same formula over time.
Why do Epley, Brzycki and Lombardi give different numbers?
They were fitted to different data and use different curves. Brzycki gives the lowest estimate from 2 to 9 reps, matches Epley at 10, and climbs fastest above that. Lombardi is the most conservative from about 8 reps up.
Do I need to test a true 1RM?
No. For tracking progress, an estimated 1RM from your regular top sets is usually enough, and it avoids a maximal attempt. Test a true max only if you compete or your program calls for it, with spotters or safety arms.