One Rep Max Calculator
Estimate your one-rep max from the weight and reps you've completed. See your estimated max, training max, rep-max estimates and training percentages.
Quick notes
- Estimates vary by formula and rep range.
- Use the average as a starting point, then adjust based on how it feels.
Formula breakdown
| Formula | Estimated 1RM |
|---|---|
| Epley | 116.67 kg |
| Brzycki | 112.5 kg |
| Lander | 113.71 kg |
| Lombardi | 117.46 kg |
| O'Conner | 112.5 kg |
| Wathan | 116.58 kg |
Percentages (based on Training Max)
| % | Weight |
|---|---|
| 50% | 51.71 kg |
| 55% | 56.88 kg |
| 60% | 62.05 kg |
| 65% | 67.22 kg |
| 70% | 72.39 kg |
| 75% | 77.56 kg |
| 80% | 82.73 kg |
| 85% | 87.9 kg |
| 90% | 93.07 kg |
| 92.5% | 95.66 kg |
| 95% | 98.24 kg |
| 97.5% | 100.83 kg |
| 100% | 103.41 kg |
Turn your estimated max into real progress
Track your lifts, PRs, strength levels and workout history with Gainzbook.
- Track personal records
- See your Strength Level
- Follow your progress over time
About the One Rep Max Calculator
The Formula
Rather than relying on a single equation, this calculator averages six widely used rep-max formulas — Epley, Brzycki, Lander, Lombardi, O'Conner and Wathan — and shows you the average alongside the lowest (conservative) and highest (aggressive) estimate. Every formula makes a slightly different assumption about how strength falls off as reps increase, so averaging several tends to be more robust than trusting any one of them on its own.
How to Use This Calculator
Enter a weight you lifted for a given number of reps, ideally taken to or close to failure — the calculator estimates what you could lift for a single rep. Use the Training Max and percentages table to plan actual training weights off that estimate (many programs use a submaximal training max, e.g. 90% of your 1RM, rather than programming off your true max directly).
How accurate is a 1RM calculator?
These formulas are estimates, not a substitute for an actual tested max. They're generally most accurate in the 1–10 rep range and become less reliable at higher rep counts, where fatigue and technique start to matter more than raw strength. Individual results also vary by lift — movements with a strong technique or fatigue component, like the deadlift, tend to estimate less precisely than more mechanically simple lifts.
Why use a Training Max?
A Training Max is a deliberately submaximal percentage of your estimated (or tested) 1RM — commonly 90% — used as the base for programming your actual training weights. Training off a Training Max rather than your true max leaves a margin for a bad day, keeps bar speed and form healthier across a training block, and gives you room to progress without constantly chasing a number that's right at your limit.