1 Rep Max Calculator

Estimate your 1 rep max for any lift from a set of reps at a known weight using the Epley or Brzycki formula.

Weight lifted (kg)

Reps performed (to near-failure)

Formula

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Fill in the details to get your result.

How This Works

Epley formula: 1RM = weight × (1 + reps/30). Brzycki: 1RM = weight × (36 ÷ (37 − reps)). Both are estimates — accuracy decreases above 5 reps. The resulting 1RM is used to calculate training percentages for programming (e.g. 80% × 5 reps for hypertrophy, 90–95% × 1–3 reps for strength).

For most lifters, actual 1RM testing every 8–12 weeks is sufficient. More frequent testing increases injury risk and detracts from training volume. Instead, use estimated 1RM from training sets (e.g. if you hit 100kg × 5 easily, your 1RM is likely 115–120kg). Beginners should avoid 1RM testing for at least 3 months while building technique.