One-Rep Max Calculator
Estimate your one-rep max from a recent set.
How It Works
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition on a given exercise. It is the benchmark for measuring strength progress and programming percentages for training.
This calculator uses two widely accepted formulas. The Epley formula estimates 1RM as weight multiplied by (1 + reps / 30). The Brzycki formula estimates 1RM as weight multiplied by 36 / (37 - reps). Both are most accurate for sets of 1 to 10 reps.
The average of the two formulas gives you a balanced estimate that smooths out the tendencies of each method — Epley tends to run slightly higher at higher rep counts, while Brzycki is more conservative.
Worked Example
Input You bench press 200 lb for 5 reps.
Result Epley: 200 x (1 + 5/30) = 233 lb. Brzycki: 200 x 36 / (37 - 5) = 225 lb. Average: 229 lb.