Health & Fitness
One-Rep Max Estimate Calculator
Estimate a one-repetition maximum from a lighter set using the Epley formula.
The result is an estimate of the heaviest weight that could be lifted once, based on a lighter set, not a directly measured maximum.
Formula
Epley one-rep max equals weight lifted multiplied by one plus repetitions divided by 30.
How it works
A submaximal set is scaled up by the Epley factor. It is most reliable for sets of up to about 10 reps; very high-rep sets make the estimate shaky.
Worked example
For example, lifting 80 kg for 8 repetitions gives an estimated one-rep max of about 101.3 kg, since 80 × (1 + 8 ÷ 30) = 101.3.
FAQs
Is this my real max?
No. It is an estimate, and true maxes vary with technique and fatigue.
Why not just test it?
Testing a true max is risky without coaching and a spotter.
What rep range works best?
Sets of 3 to 10 reps give the most useful estimates.
General information only, not medical advice.
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