1RM calculator
Your one-rep max is the heaviest weight you could lift once. You do not have to test it: enter a set you actually did and the estimate tells you what to load for every rep range.
Estimated 1RM
— kg
Epley — · Brzycki —
How the estimate works
Every 1RM formula turns a submaximal set into a maximum. We show the two most used ones and take their average; they agree closely up to about 6 reps and drift apart after that, which is why sets above 12 reps are not accepted.
The formulas
Epley 1RM = weight × (1 + reps ÷ 30) Brzycki 1RM = weight × 36 ÷ (37 − reps)
Training loads from your 1RM
| Reps per set | % of 1RM | Typical use |
|---|---|---|
| 1–3 | 90–100% | Max strength |
| 4–6 | 85–90% | Strength |
| 8–10 | 75–80% | Strength and size |
| 12 | 70% | Size and endurance |
An estimate, not a test result: technique, fatigue and the exercise itself move the real number. Do not attempt a true one-rep max without a spotter or safety pins. Sources: Epley B. Poundage chart. Boyd Epley Workout, 1985. Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. JOPERD. 1993;64(1):88–90.
How we calculate, with sources →
1RM questions
Which set should I enter?
The heaviest set you completed with good form recently, ideally 3–6 reps: the fewer the reps, the closer the estimate.
Why do Epley and Brzycki differ?
They were fitted on different lifters and exercises. Brzycki is a little lower for high-rep sets; the average is a fair middle.
Does the formula work for every exercise?
Best for barbell lifts (squat, bench, deadlift). For isolation work and bodyweight exercises treat it as a rough guide.