1-Rep Max Calculator
Estimate your one-rep max (1RM) from a recent set — no need to test it directly.
Estimates get less accurate above ~10–12 reps. Always warm up and use a spotter for true max attempts.
How it's calculated
This tool uses the Epley formula — weight × (1 + reps ÷ 30) — to estimate your one-rep max from a set you've actually performed, without needing to test a true max.
How to use your result
Use the estimate to set training percentages (for example, 80% of 1RM for a strength block) rather than as a number to chase directly — it's a planning tool, not a target.
Common mistakes
Estimating from very high-rep sets. Accuracy drops the further a set gets from a near-max effort, so a set of 3-5 reps gives a more reliable estimate than a set of 15.
When to talk to a coach
Testing or approaching an actual 1RM safely takes technique, a proper warm-up progression, and a spotter — work with a coach before attempting a true max lift.