# Epley Formula (1 rep max)

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vCalc.Epley Formula (1 rep max)
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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:

where:

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.