One Rep Max (1RM) Calculator

Estimate your maximum single-rep lift weight from any weight and rep combination using proven formulas.

kg
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Estimated 1 Rep Max

Why Calculate Your 1RM?

Your 1RM is used to set training percentages. Most strength programmes prescribe loads as % of 1RM (e.g. 80% for 5 reps). Use caloriecalcfree.com to estimate safely without maxing out.