One Rep Max (1RM) Calculator
Estimate your one-rep max from the weight and reps you lifted.
Uses the Epley formula to calculate your maximum strength for any exercise.
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Estimated 1RM
Your one-rep max (1RM) is the maximum weight you can lift for exactly one complete repetition with proper form. Rather than risk injury testing it directly, most lifters estimate it from a submaximal set using a formula.
The Epley Formula:
1RM = Weight × (1 + Reps / 30)
The Brzycki Formula:
1RM = Weight × 36 / (37 − Reps)
The Lombardi Formula:
1RM = Weight × Reps^0.1
Worked Example:
You squat 120 kg for 6 reps.
- Epley: 120 × (1 + 6/30) = 120 × 1.2 = 144 kg
- Brzycki: 120 × 36 / (37 − 6) = 120 × 36/31 = 139 kg
- Lombardi: 120 × 6^0.1 = 120 × 1.196 = 143 kg
Average of three formulas: 142 kg — a reliable working estimate.
Training Percentages Based on 1RM:
| Goal | % of 1RM | Sets × Reps |
|---|---|---|
| Max strength | 90–100% | 1–3 × 1–3 |
| Strength | 80–90% | 3–5 × 3–5 |
| Hypertrophy | 67–80% | 3–5 × 6–12 |
| Muscular endurance | 50–67% | 2–3 × 15–20 |
1RM Standards by Lift (intermediate male lifter, ~80 kg bodyweight):
| Lift | Intermediate 1RM |
|---|---|
| Back squat | 120 kg |
| Bench press | 100 kg |
| Deadlift | 140 kg |
| Overhead press | 65 kg |
Practical Tips:
- Use sets of 3–5 reps for the most accurate 1RM estimates; accuracy drops significantly above 12 reps
- Retest every 6–8 weeks during a strength phase to keep training weights current
- The formula overestimates for very high rep sets (15+) because fatigue distorts the calculation