One Rep Max Calculator

Enter Your Lift

Exercise

Unit

Weight Lifted (lbs)

Reps Performed (1-30)

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Enter the weight you lifted and how many reps you completed to estimate your one rep max across 7 proven formulas.

About the Formulas

Epley (1985)weight x (1 + reps/30)

One of the most widely used formulas. Works best for rep ranges of 1-10. Tends to overestimate at higher rep counts.

Brzycki (1993)weight x 36 / (37 - reps)

Very popular in academic and professional settings. Most accurate in the 1-10 rep range. Produces identical results to Epley at 10 reps.

Lander (1985)100 x weight / (101.3 - 2.67123 x reps)

A linear regression model. Provides consistent estimates across moderate rep ranges.

Lombardi (1989)weight x reps^0.10

A power-law based formula. Tends to give more conservative estimates compared to other formulas.

Mayhew et al. (1992)100 x weight / (52.2 + 41.9 x e^(-0.055 x reps))

Developed using collegiate football players. Uses an exponential model for a good fit across wider rep ranges.

O'Conner et al. (1989)weight x (1 + 0.025 x reps)

A simple linear model. Generally provides the most conservative estimates and works well for low rep ranges.

Wathan (1994)100 x weight / (48.8 + 53.8 x e^(-0.075 x reps))

An exponential model that tends to produce slightly higher estimates. Often used alongside Epley and Brzycki for comparison.

Disclaimer: These formulas provide estimates only. Actual 1RM may vary based on training experience, fatigue, technique, and individual biomechanics. Always use a spotter when attempting maximal lifts. Consult a qualified trainer before testing your one rep max.