Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition, commonly used to plan training percentages for strength programs.
This calculator uses the Epley formula, which estimates 1RM from the weight you lifted and the number of reps you completed before failure.
Example: Bench pressing 80 kg for 5 reps:
1RM = 80 × (1 + 5/30) = 80 × 1.167 = 93.3 kg
It's a solid estimate for reps under about 10, but accuracy decreases at higher rep ranges - testing your true 1RM directly is more precise.
The Epley formula: 1RM = weight \u00d7 (1 + reps/30), one of the most widely used strength estimation formulas.
Many strength programs prescribe training weights as a percentage of your 1RM, so knowing it helps you set accurate training loads.