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One-Rep Max Calculator

Estimate your 1RM from any weight and rep count. Plan training percentages without testing a true max.

How it works

Two well-validated formulas. We average them for a robust estimate:

Brzycki: weight × (36 / (37 − reps))
Epley: weight × (1 + reps / 30)

Both are most accurate at 1–10 reps. Above 10, error climbs. Use the result to plan percentages: a working set at 75% of 1RM, accessory volume at 65%, and so on.