Epley formula

In plain words

Epley's is the usual formula for turning a set into a max estimate: one-rep max = weight × (1 + reps ÷ 30). Each rep you did adds a thirtieth of the weight on the bar, about 3.3%, so ten reps add a third. Turned round, it gives the weight for a rep target: for a 100 kg max, 5 reps works out at 85.7 kg. It is not a law. A 2026 preprint by Marzagão traces it to a poundage chart in a 1985 training manual for athletes at the University of Nebraska, not to a peer-reviewed study. A 2006 study advised using no more than 10 reps for estimates of this kind.

An example

A set of 60 kg for 10 reps. Ten reps divided by 30 is a third, so the multiplier is 1.333: 60 × 1.333 = 80 kg. That 80 kg is the estimated one-rep max from one ordinary set. The Brzycki formula gives the same 80 kg at 10 reps. Below ten they part: 80 kg for 5 reps is 93.3 kg by Epley and 90.0 kg by Brzycki.