One Rep Max (1RM) Calculator
Estimate your one-repetition maximum using the Epley, Brzycki, and Lombardi formulas from a submaximal lift.
Results
What is it?
Your One-Rep Max (1RM) is the maximum weight you can lift for a single repetition with correct form. It is the gold standard for measuring absolute strength. Rather than maxing out (which carries injury risk), these formulas let you estimate your 1RM from a submaximal effort (e.g. 5 reps at 80 kg).
How to use
1. Select your weight unit (kg or lb). 2. Enter the weight you lifted. 3. Enter the number of complete reps you performed at that weight. 4. The calculator displays estimates from three established formulas, plus an average, and useful training percentages.
Example scenario
Lifted 80 kg for 8 reps. Epley: 80 x (1 + 8/30) = 101.3 kg. Brzycki: 80 x 36/(37-8) = 99.3 kg. Lombardi: 80 x 8^0.10 = 91.4 kg. Average = 97.3 kg. At 80% (77.9 kg) you would target 8-12 rep sets for hypertrophy.
Pro tip
The Epley formula tends to overestimate at high rep counts (>10), while Brzycki is more accurate for lower reps (3-6). For the most precise 1RM, test it directly on a day you are fresh and well-warmed-up. Always train with a spotter when attempting heavy singles.