Strength training
One Rep Max Calculator: Formula, Chart and How to Use It
Published October 20, 2026
Your one rep max (1RM) is the heaviest weight you can lift once with good form. You can estimate it safely from a set of 3-10 reps with the Brzycki formula: 1RM = weight ÷ (1.0278 − 0.0278 × reps), published in 1993 (Brzycki, 1993). Estimates are most accurate from sets of 3-6 reps taken close to failure.
1RM chart (Brzycki)
| Reps completed | % of 1RM | Multiply the weight by |
|---|---|---|
| 1 | 100% | 1.00 |
| 2 | 97% | 1.03 |
| 3 | 94% | 1.06 |
| 4 | 92% | 1.09 |
| 5 | 89% | 1.13 |
| 6 | 86% | 1.16 |
| 7 | 83% | 1.20 |
| 8 | 81% | 1.24 |
| 9 | 78% | 1.29 |
| 10 | 75% | 1.33 |
Worked examples
| Lift | Set | Estimated 1RM |
|---|---|---|
| Bench press | 185 lb × 5 | 185 × 1.13 ≈ 208 lb |
| Squat | 100 kg × 6 | 100 × 1.16 ≈ 116 kg |
| Deadlift | 275 lb × 3 | 275 × 1.06 ≈ 291 lb |
Accuracy: what to know
- Best between 3 and 6 reps; beyond 10 reps the error grows.
- The set must be close to failure with clean technique.
- Less reliable on small isolation exercises.
- Your real max varies day to day with sleep and stress.
Programming with percentages
| Goal | % 1RM | Reps | Sets |
|---|---|---|---|
| Max strength | 85-95% | 1-5 | 3-6 |
| Strength + size | 75-85% | 5-8 | 3-5 |
| Hypertrophy | 60-80% | 8-15 | 3-4 |
| Muscular endurance | < 60% | 15+ | 2-3 |
For muscle size, light and heavy loads give similar results when sets go near failure; for max strength, heavy loads win (Schoenfeld et al., 2017).
4-week squat block (estimated 1RM 265 lb / 120 kg)
| Week | Prescription | Load |
|---|---|---|
| 1 | 4 × 6 at 75% | 200 lb / 90 kg |
| 2 | 4 × 5 at 80% | 210 lb / 95 kg |
| 3 | 5 × 3 at 85% | 225 lb / 102.5 kg |
| 4 | AMRAP at 85% → new estimated 1RM | 225 lb / 102.5 kg |
Should you test a true 1RM?
| Pros | Cons |
|---|---|
| Needed for powerlifting meets | Risky with shaky technique |
| Motivating | Fatiguing, little value for muscle growth |
If you test: warm up progressively (see warm-up exercises), use spotters or safety bars, never max out alone on the bench press.
Easier day to day: RPE
Instead of fixed percentages, many lifters set loads by reps in reserve: RPE and RIR. More on technique: bench press, squat, deadlift.