One Rep Max Calculator
Estimate your one-rep max based on the weight you lifted and the number of repetitions you completed.
Weight Lifted
lbs
Reps Completed
Calculated instantly in your browser — nothing is sent to or stored on our servers.
How This Is Calculated
Your one-rep max (1RM) is the most weight you could lift for a single repetition. Testing it directly is risky, so most lifters estimate it from a lighter set taken to or near failure.
The Formula
1RM = weight lifted × (1 + reps ÷ 30) — the Epley formula, one of the most commonly used 1RM estimates.
Accuracy Notes
This formula is most accurate for sets of about 10 reps or fewer. Higher-rep sets tend to overestimate true one-rep max.
An estimate for programming, not a guarantee.
Use your estimated 1RM to plan training percentages, not as a target to attempt directly without proper warm-up and spotting.
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