How it works
Epley: 1RM = w × (1 + reps ÷ 30)
Brzycki: 1RM = w × 36 ÷ (37 − reps)
The main result is the average of Epley and Brzycki. The estimates are most accurate for sets of 2–10 reps taken close to failure with good form.
One rep max (1RM) calculator
Enter the weight you lifted and how many clean reps you managed. The calculator estimates the most you could lift once and lists training loads at each percentage.
Estimated one rep max
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Show training loads by percentage
This calculator gives a general estimate for adults and is not medical advice. Talk to a doctor or a registered dietitian before making health decisions.
Common questions
Is it safe to test a true 1RM?
Only with a solid warm-up, good technique and a spotter or safety bars. Estimating from a set of 3–5 reps is safer for most people.
What percentage should I train at?
Roughly 80–90% for strength (3–6 reps), 65–80% for muscle growth (6–12 reps) and below 65% for endurance work.