Estimated one rep max
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| % of 1RM | Weight | Est. reps |
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Enter a set you've done and get your estimated 1RM plus the weight for every training percentage.
| % of 1RM | Weight | Est. reps |
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Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition of an exercise. It is the reference point strength programmes are built around, because most training is prescribed as a percentage of it: heavy strength work sits around 85–95% of 1RM, hypertrophy (muscle-building) work around 67–85%, and endurance work below that. Rather than max out often, most lifters estimate their 1RM from a lighter set.
How it is estimated. Formulas such as Epley and Brzycki predict your 1RM from the weight and number of reps you can do: for example, weight × (1 + reps ÷ 30) in the Epley formula. These are most accurate at lower rep counts (up to about five); above ten reps the estimate drifts, because endurance and technique start to matter more than raw strength.
Use it safely. Treat the estimate as a training guide, not a target to test every week. Actually attempting a true 1RM is demanding and carries injury risk, so it should be done rarely, well warmed up, and ideally with a spotter. The calculator above estimates your max from a set you can complete with good form.