1-Rep Max Calculator
Estimate your one-rep maximum (1RM) strength from any weight and reps set.
Your Lift
Enter the weight you lifted and the number of reps to estimate your 1RM
Safety note: Never attempt a true 1RM without a spotter and proper warm-up. These are estimates. Accuracy is highest for 1–10 reps; predictions become less reliable above 10 reps.
Estimate your one-rep maximum (1RM) for any lift by entering the weight you lifted and the number of reps completed. Compare results from five scientific formulas and see training weights for every rep range.
Key Features
Five scientific formulas
Calculates 1RM using Epley, Brzycki, Lombardi, Mayhew, and O'Conner formulas, then shows them side by side in a bar chart.
Formula comparison chart
A horizontal bar chart lets you visually compare results across all five formulas and see the range of estimates.
Training weight table
Automatically calculates training weights at 10 rep ranges from 1 to 15 reps based on your estimated 1RM.
kg / lb toggle
Switch between kilograms and pounds. Works with any barbell lift.
How to Use
- 1Select your exercise from the dropdown (optional, for labelling).
- 2Enter the weight you lifted and the number of reps you completed.
- 3View your average estimated 1RM and the formula breakdown.
- 4Use the training table to find appropriate weights for your target rep range.