How it works

The calculator uses the Epley formula — the same equation behind most 1RM estimators — run in reverse. Given a target 1RM, it solves for the weight you'd need to lift across 2 to 8 reps such that the estimated max comes out at your goal.

Pick the rep range that matches how you train. If you're following a strength program like 5/3/1 or a linear progression, the 5-rep row is usually the most useful starting point. The Est. 1RM column shows what the formula predicts you'd hit based on that weight and reps — useful for checking the numbers make sense.

The formula is an estimate, not a guarantee. Individual variation, fatigue, and technique all affect actual performance. Use it as a target to train toward, not a number to chase on a given day.