What is one rep max (1RM)?

The maximum amount of weight you can lift for exactly one repetition of a given exercise with proper form.

Which 1RM formula is most accurate?

Epley and Brzycki formulas are the most widely used. Accuracy decreases significantly when the rep count exceeds 10.

How do I use my 1RM for training?

Use 70–80% of 1RM for hypertrophy (muscle building), 85–95% for strength training, and 50–65% for muscular endurance work.

One Rep Max Calculator

Your One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form for a given exercise. It is a key metric in strength training for programming workout intensity and tracking progress over time.

Epley and Brzycki are the most widely used and validated formulas. All formulas become less accurate as the number of reps increases beyond 10, since fatigue and technique become larger factors. For best results, use 3–5 rep sets when estimating your 1RM.

Use the percentage table to guide your training intensity:

50–60%: Warm-up, technique work, rehab
70–80%: Hypertrophy (muscle building) — 8–12 reps
80–85%: Strength-hypertrophy hybrid — 5–8 reps
85–95%: Strength — 1–5 reps
95–100%: Maximal strength / competition prep

One Rep Max Calculator

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