Epley vs Brzycki: Two 1RM Formulas Give Different Results — Here Is How to Use Each

Two widely used one-rep max estimation formulas — Epley (1985) and Brzycki (1993) — can produce noticeably different results from the same lifting set, with a gap of around 4 kg observed when estimating from 100 kg lifted for 5 reps. This discrepancy becomes practically significant when calculating percentage-based training loads, such as programming a 5x5 session at 85% of 1RM. Research from LeSuer et al. (1997) and Wood et al. (2002) suggests each formula performs better within certain rep ranges. Fitness professionals recommend using the more conservative of the two estimates when attempting heavy percentage lifts, and an average of both for general programming reference. Notably, neither formula was validated beyond 10 reps, as muscular endurance and glycogen factors begin to dominate at higher rep counts, making both less reliable in that range.