One Rep Max Calculator
Lift a weight for reps, get your max — by the two formulas every strength coach uses — plus your training percentages.
Estimate your one rep max
The two formulas
Both convert a multi-rep set into an estimated single-rep maximum. They agree closely under 6 reps and drift apart above 10 — Epley runs slightly more generous at high reps. 225 lb for 5 reps estimates a 1RM around 262–253 lb depending on formula; this calculator shows both and the average, which is the sensible number to train from.
Why estimate instead of test
True max attempts are taxing, technically risky when fatigued, and unnecessary for most training purposes. A hard set of 3–5 reps, plugged into the formulas, gets within a few percent with a fraction of the strain — which is why nearly every percentage-based program (5/3/1, Texas Method, most powerlifting templates) runs on an estimated or "training max" rather than a fresh gym PR. Accuracy degrades past ~10 reps, where endurance contaminates the strength signal: estimate from sets of 3–6 for best results.
Using the percentages
The standard intensity map: 85–95% for low-rep strength work (1–5 reps), 70–85% for muscle-building sets of 6–12, 60–70% for volume, technique, and warm-ups. Many programs deliberately train off 90% of true max to keep bar speed and recovery healthy. Re-estimate every 4–6 weeks from a recent hard set rather than chasing the calculator's number on a bad day — the formula describes your strength; it doesn't owe it to you on demand.
Frequently asked questions
Which formula is more accurate?
Below 6 reps they're nearly identical. Brzycki tends to fit bench press data slightly better; Epley flatters squats and deadlifts at higher reps. The average of both is a robust practical choice.
Should beginners test a real 1RM?
Generally no — early strength gains are mostly skill acquisition, and maximal attempts before technique solidifies invite injury. Train with rep estimates for the first several months; the formulas track your progress fine.
Why is my real max lower than the estimate?
Singles are their own skill — bracing, psychology, and bar-path precision under maximal load. High-rep estimators also flatter endurance-leaning lifters. The gap closes with practice at heavier percentages.
Do these formulas work for every exercise?
Best for the barbell lifts they were built on (squat, bench, deadlift, press). For isolation moves and machines the estimates are rough, and for explosive lifts like cleans, rep math barely applies.