One Rep Max Calculator
Calculate your estimated one rep max using multiple proven formulas. Get a complete percentage chart for your training.
kg
reps
💡 Tip
Use a weight you can lift for 2-10 reps for best accuracy. Formulas become less accurate above 10 reps.
Estimated 1RMAverage of 4 formulas
0 kg
Based on 100 kg × 5 reps
Epley
kg
Brzycki
kg
Lombardi
kg
O'Conner
kg
Training Percentages
Safety Note
These are estimates. Never attempt a true 1RM without proper warm-up, a spotter, and experience. Use the percentage chart as training guidelines.
Documentation
The Formulas
Epley
1RM = W × (1 + R/30)
Brzycki
1RM = W × (36 / (37 - R))
Lombardi
1RM = W × R^0.10
O'Conner
1RM = W × (1 + R/40)