e1RM calculator
Estimate your one-rep max from a safe working set. Three formulas, a confidence rating and ready percentage-based loads.
Everything is computed in your browser — the values you enter are never sent or stored.
Result
- Estimated 1RM (Epley)
- 116.7 kg
- Brzycki
- 112.5 kg
- Lombardi
- 117.5 kg
- Confidence
- estimate
Percentage loads
| % 1RM | Weight | Typical use |
|---|---|---|
| 95% | 110.8 kg | max strength, 1-2 reps |
| 85% | 99.2 kg | strength, 3-5 reps |
| 75% | 87.5 kg | hypertrophy, 8-10 reps |
| 65% | 75.8 kg | volume, 12-15 reps |
| 50% | 58.3 kg | technique, warm-up |
Do not test a true 1RM without experience and a spotter. Estimating from a working set is safer and good enough for planning.
How we calculate this
- Epley: e1RM = weight × (1 + reps / 30)
- Brzycki: e1RM = weight × 36 / (37 − reps)
- Lombardi: e1RM = weight × reps^0.10
The formulas come from the app’s domain specification and are covered by unit tests. The same code powers zones inside the app.
Want these numbers to feed your plan automatically?
In the app, zones update after every test and the plan adapts to your data and how you feel.
This calculator is informational and does not replace a doctor, physiotherapist or coach. Results based on population formulas are estimates, not measurements. Read the full disclaimer →