1RM Calculator: Estimate Your One-Rep Max
Calculate your 1RM
Brzycki and Epley equations.
| Reps | Weight | % 1RM |
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Your 1RM can be estimated from a set of several reps, for example with the Brzycki formula (weight × 36 ÷ (37 − reps)) or the Epley formula. The calculator shows both results and a table for 1 to 12 reps.
How the 1RM is estimated
The 1RM (one-repetition maximum) is the weight that can be lifted exactly once with good form. Instead of testing it directly, it can be estimated from a set of several reps. Brzycki (1993) describes the formula weight × 36 ÷ (37 − reps); the Epley formula is weight × (1 + reps ÷ 30). The calculator shows both values and their average.
How reliable is the estimate?
LeSuer et al. (1997) compared several prediction equations, including Brzycki and Epley, for the bench press, squat and deadlift. Kravitz et al. (2003) concluded that in powerlifters, 1RM in these lifts can be predicted from submaximal tests with an acceptable degree of accuracy. The calculator accepts 1 to 12 reps.
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- Brzycki, M. (1993). Strength Testing—Predicting a One-Rep Max from Reps-to-Fatigue. Journal of Physical Education, Recreation & Dance, 64(1), 88–90. DOI
- LeSuer, D. A., McCormick, J. H., Mayhew, J. L., Wasserstein, R. L. & Arnold, M. D. (1997). The Accuracy of Prediction Equations for Estimating 1-RM Performance in the Bench Press, Squat, and Deadlift. J Strength Cond Res, 11(4), 211–213. DOI
- Kravitz, L., Akalan, C., Nowicki, K. & Kinzey, S. J. (2003). Prediction of 1 repetition maximum in high-school power lifters. J Strength Cond Res, 17(1), 167–172. PubMed