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One Rep Max Calculator
Estimate your one-rep max (1RM) from a set of reps using the Epley, Brzycki and Lombardi formulas, with a percentage chart.
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How to use this calculator
Enter your values. The result updates as you type; press Calculate to confirm and jump to the result on mobile. Use Share to send the calculator with your result.
1RM formulas
Epley: 1RM = w × (1 + reps ÷ 30)
Brzycki: 1RM = w × 36 ÷ (37 − reps)
Lombardi: 1RM = w × reps^0.10
Example: 100 kg for 5 reps → Epley 116.7 kg, Brzycki 112.5 kg, Lombardi 117.5 kg. The formulas agree closely at low reps and drift apart as reps rise.
Why estimate instead of testing?
A true max attempt is fatiguing and carries more injury risk, especially without a spotter. Estimating from a hard set of 3–8 reps gives a usable number to plan training percentages.
Using percentages
Strength programs prescribe loads as a % of 1RM: roughly 85%+ for strength (1–6 reps), 65–85% for hypertrophy (6–12 reps) and below 65% for endurance work. The rep column is a typical guide; individuals vary.
Frequently asked questions
Which 1RM formula is most accurate?
None is best for everyone. Epley and Brzycki are the most widely used and are reliable up to about 10 reps.
How do I calculate my bench press max?
Enter a weight you lifted for 3–8 hard reps; the tool estimates the max.
About this tool
- Written by
- [Author: to be assigned]
- Reviewed by
- Expert review pending
- Last updated
- 31 Oct 2026
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