1RM Calculator
Lift heavy without testing a max. Plug in a weight × reps set and get your estimated 1RM across the three most-cited formulas.
Inputs
Formulas lose accuracy above 12 reps.
Result
- Epley116.7kg
- Brzycki112.5kg
- Lombardi117.5kg
- Average estimate115.5kg
Calculations run locally in your browser. Nothing is sent to a server.
Three published 1RM formulas: Epley (1985, weight × (1 + reps/30)), Brzycki (1993, weight / (1.0278 - 0.0278 × reps)), Lombardi (1989, weight × reps^0.10). Each over-estimates at high reps. Average all three for a safer working number.
References
How accurate are 1RM estimates?
Within ±5% if you're truly grinding the last rep at RPE 9–10. Above 8 reps the error widens to ±10%, so do your AMRAPs at 3-6 reps for the best signal.
Should I program off 1RM or e1RM?
Most experienced lifters program off estimated 1RM (e1RM) updated weekly. Ascend tracks this automatically as you log sets.
Do these formulas work for women?
Yes. The formulas are sex-agnostic; only the absolute load changes.
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