Free Tool
Brzycki 1RM Calculator
Calculate your one rep max using the Brzycki formula. Enter weight and reps for an accurate 1RM estimate.
1RM formulas are most accurate for 1–10 reps. Results above 15 reps become less reliable.
The Brzycki formula
The Brzycki formula was developed by Matt Brzycki and published in 1993. It uses the following equation:
1RM = weight × 36 / (37 − reps)
Example: 225 lbs × 5 reps → 1RM = 225 × 36 / (37 − 5) = 225 × 36 / 32 = 253.1 lbs
Brzycki is widely considered accurate for sets of 1–10 reps and tends to produce slightly more conservative estimates than the Epley formula. This conservative bias is actually useful for programming: it is better to set training weights that are achievable and build from there than to set them too high and miss lifts or accumulate fatigue. Many powerlifting coaches use Brzycki as their primary 1RM estimator for this reason.
Note that the Brzycki formula becomes undefined as reps approach 37, so it is only meaningful for rep counts of 36 or fewer. In practice, 1RM estimates from sets above 15 reps are unreliable regardless of formula and should only be used as a rough reference.
Compare other methods
The Epley formula is the most commonly cited 1RM equation and tends to produce slightly higher estimates. The Lombardi formula uses an exponential model that often gives the most conservative results. To compare all three side by side, visit the main 1RM calculator.
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