One Rep Max Calculator
Estimate your max one-rep lift, the max weight you can lift for a single repetition for a given exercise.
How We Calculate This
There's no single "most accurate" formula for estimating a one-rep max from a submaximal set — every
equation is a population-average approximation, so we show you two of the most widely used ones side by
side instead of picking a favorite.
The Epley formula (1RM = weight × (1 + reps/30)) is the most widely used approximation
in gyms and coaching, originally published as a poundage chart rather than in a peer-reviewed journal.
The Brzycki formula (1RM = weight × 36 ÷ (37 − reps)) comes from a peer-reviewed paper
and tends to estimate slightly lower than Epley at higher rep counts. It becomes mathematically
undefined at 37 reps or more (the denominator hits zero), so it isn't usable outside a realistic
strength-testing rep range.
Both formulas are most reliable for sets of 1–10 reps — accuracy drops the higher your rep count goes,
since fatigue and muscular endurance start to matter more than raw strength. For the most reliable
estimate, use a recent set of 1–6 reps taken close to failure.
Once you have an estimate, the Training Load Table below it converts that number into
practical training weights using the NSCA's percentage-of-1RM chart — so you can see what to load on the
bar for a strength-focused set of 3 reps versus a hypertrophy-focused set of 8, without doing the math
yourself.
Source: Brzycki, M. (1993). Strength testing—Predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation & Dance, 64(1), 88–90.
Read the Brzycki study →
Source: Landers, J. (1984). Maximum based on reps. NSCA Journal, 6(6), 60–61.
Read the NSCA training load chart →