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Redmoon Converters
🏋️ Strength & Fitness

One Rep Max (1RM) Calculator + % Chart

Estimate your 1RM from any reps × weight using five validated formulas, with a full %1RM table (50–100% in 5% steps) for programming sets and reps.

Best within 1–10 reps; >12 less accurate.
Back Squat · Estimated 1RM
Average formula
%1RMWeightSuggested reps
How the math works

Epley: w × (1 + reps/30). Brzycki: w × 36 / (37 − reps). Lombardi: w × reps^0.10. O'Conner: w × (1 + 0.025 × reps). Wathan: 100 × w / (48.8 + 53.8 × e^(−0.075 × reps)).

The %1RM chart uses standard rep-range pairings (95% ≈ 2 reps, 85% ≈ 5 reps, 70% ≈ 10 reps, etc.).

Also known as

1rm calculatorone rep max calculatorbench press max calculator%1rm chart

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