Epley Formula (1 rep max)

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Equation / Last modified by KurtHeckman on 2019/01/08 22:36
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vCalc.Epley Formula (1 rep max)

The Epley 1 Rep Max Formula calculator computes the one repetition max using the Epley formula, the weight lifted and the number of repetitions.

INSTRUCTIONS: Choose weight units and enter the following:

  • (w)  This is the weight lifted.
  • (r)  This is the number of repetitions achieved.

One Rep Max (RM): The calculator returns the One Repetition Maximum in pounds.  However, this can be automatically converted to other weight units (e.g. kilograms) via the pull-down menu.

The Math / Science

The Epley Formula for one repetition max is as follows:

    RM = W•(1 + r/30)


The formula estimates how much the weight lifter could have lifted one time (RM) based on the maximum number of reps (r) of a lesser weight (w).  This method is used in some competitions and in many gyms to avoid injuries and to provide a more consistent measure of endurance and strength.

Weight Lifting Calculators