One-rep max calculator
Estimated 1RM from a set, plus a full percentage-of-max training table.
Estimates only — warm up and lift within your ability.
Accuracy falls off above about 10
Average of five formulas · round to 115 kg on the bar
Training percentages
| % of 1RM | Weight | Rounded | Typical reps |
|---|---|---|---|
| 100% | 115.1 kg | 115 kg | 1 |
| 95% | 109.4 kg | 110 kg | 2 |
| 90% | 103.6 kg | 102.5 kg | 4 |
| 85% | 97.9 kg | 97.5 kg | 6 |
| 80% | 92.1 kg | 92.5 kg | 8 |
| 75% | 86.4 kg | 87.5 kg | 10 |
| 70% | 80.6 kg | 80 kg | 12 |
| 65% | 74.8 kg | 75 kg | 15 |
| 60% | 69.1 kg | 70 kg | 20 |
How it works
A one-rep max is the heaviest weight you can lift once with good form. Testing it directly is taxing and carries risk, so it is usually estimated from a submaximal set instead.
Epley: 1RM = w × (1 + reps/30)
Brzycki: 1RM = w × 36 / (37 − reps) Why five formulas?
They were each fitted to different populations and lifts, and they disagree — particularly above six reps. Brzycki tends to read low at high reps, Epley high. Showing the spread is more honest than picking one and presenting it as fact; the average is a reasonable working number.
It varies by lift and by person
Deadlifts and squats generally produce more reps at a given percentage than bench press, because larger muscle groups fatigue differently. Training history matters too — a lifter who trains heavy singles will out-perform their estimated max, and one who trains high reps will fall short of it.
Use it as a planning tool
Percentage-based programmes need a number to work from, and this is a good enough one. Re-estimate every few weeks rather than treating a single figure as fixed. If a prescribed weight feels wrong on the day, trust the day.
Sources
Epley B, Boyd Epley Workout, 1985. Brzycki M, “Strength testing: predicting a one-rep max from reps to fatigue”, JOPERD, 1993. Also Lombardi, O'Conner and Wathan as commonly cited in strength-training literature.