Rep Max Calculator
Estimate 1RM through 12RM values from a completed set or from a known one-rep max. Results update as you change an input.
Result
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What is a rep max?
A rep max is the greatest load someone can lift for a specified number of technically valid repetitions.
1RM, 3RM, 5RM, and 10RM
A 1RM represents a maximal single. Higher rep maxes use lighter loads and involve progressively more local fatigue and endurance.
Why rep-max estimates vary
Exercise, technique, tempo, training history, fatigue, and proximity to failure all influence the relationship between repetitions and load.
Why high-rep estimates are less reliable
Small pacing and endurance differences accumulate in longer sets, so high-repetition sets generally predict maximal strength less consistently.
Method note: The Epley model is applied consistently with this site’s general 1RM calculator. See a review of 1RM prediction validity.