About One Rep Max Calculator
One-rep max (1RM) is the heaviest weight you can lift once with good form. This calculator estimates it from a lighter set using two formulas: Epley, 1RM = weight × (1 + reps ÷ 30), and Brzycki, 1RM = weight × 36 ÷ (37 − reps). The 90%, 80%, and 70% training loads are based on the Epley value. Estimates are limited to 1 to 12 repetitions and become less reliable as reps increase.
How to use One Rep Max Calculator
- Fill in "Weight lifted" and "Repetitions".
- The result appears below and updates as you type.
- Copy the result with the copy button, or download it as a file where that is offered.
Questions about One Rep Max Calculator
Which is more accurate, Epley or Brzycki?
Both are close for sets of up to about 10 repetitions and agree exactly at 10. Brzycki gives slightly lower values at low reps. Neither replaces a supervised test of your true maximum.
Can I enter the weight in pounds?
Yes. The formulas are proportional, so if you type pounds the results are in pounds too. Just read every kg label as lb.
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