One Rep Max Calculator
Estimate your one-rep max (1RM) and get a complete percentage chart for programming your training.
Enter a weight you can lift for multiple reps (ideally 2-10 reps).
How This Calculator Works
This calculator uses the average of five validated formulas (Brzycki, Epley, Lander, Lombardi, O'Conner) to estimate your one-rep max from submaximal performance.
Best accuracy: Use weights you can lift for 2-6 reps. Higher rep ranges (10+) become less accurate as muscular endurance plays a larger role.
Safety note: These are estimates. When actually testing your 1RM, always use a spotter and start conservatively.
How do you calculate your one-rep max?
Lift a weight for as many clean reps as you can, ideally 3 to 10, then put the weight and reps into a formula. The Epley formula is 1RM = weight × (1 + reps ÷ 30); Brzycki is weight × 36 ÷ (37 − reps). For example, 100 kg for 5 reps estimates a 1RM of about 117 kg (Epley) or 113 kg (Brzycki).
1RM percentage chart
Typical reps at each percentage of your one-rep max, with the load for a 100 kg 1RM. Individuals vary by a rep or two.
| % of 1RM | Typical reps | Load at a 100 kg 1RM |
|---|---|---|
| 100% | 1 | 100 kg |
| 95% | 2 | 95 kg |
| 93% | 3 | 93 kg |
| 90% | 4 | 90 kg |
| 87% | 5 | 87 kg |
| 85% | 6 | 85 kg |
| 83% | 7 | 83 kg |
| 80% | 8 | 80 kg |
| 77% | 9 | 77 kg |
| 75% | 10 | 75 kg |
| 70% | 12 | 70 kg |
| 65% | 15 | 65 kg |
How to use your 1RM in training
- Strength: 3 to 6 reps at 80 to 90% of 1RM.
- Muscle growth: 6 to 12 reps at 65 to 80% of 1RM.
- Technique and volume: 12 to 15 reps at 60 to 70% of 1RM.
- Re-estimate every 4 to 8 weeks from a hard set, rather than testing a true max often.
Turn your 1RM into a plan
12-Week Muscle Building: four sessions a week in three phases, with the rep ranges and progression rules set out for you. 36-page PDF, £29.
See the 12-Week Muscle BuildingCommon questions
How accurate is a 1RM calculator?
Estimates are most accurate from sets of 3 to 10 reps taken close to failure with good form. Above about 10 reps the formulas drift, usually overestimating. Use the estimate to set training loads, not as a record.
Which 1RM formula is best?
Epley and Brzycki agree closely between 3 and 10 reps. Brzycki is slightly more conservative at low reps; Epley at higher reps. Pick one and use it consistently so your progress stays comparable.
Is it safe to test a true one-rep max?
Testing a true max adds risk and fatigue, which is why most people estimate it. If you do test, warm up thoroughly, use spotters or safety bars, and stop the attempt if your form changes.
Related: what 1RM means · strength standards · plate calculator