Health & Training

One-Rep Max (1RM) Calculator

Estimate your one-rep max from a set you've already done. Uses the two best-known formulas — Epley and Brzycki — so you can program strength work without ever maxing out.

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How 1RM estimates work

You don't need to attempt a true max to know roughly what it is. From the weight and reps of a hard submaximal set, well-validated formulas estimate your one-rep max. This tool averages the two most widely used — Epley (weight × [1 + reps ÷ 30]) and Brzycki (weight × 36 ÷ [37 − reps]) — which agree closely in the low-rep range and diverge as reps climb.

Using your training percentages

The real value of a 1RM estimate is programming. Most strength work is prescribed as a percentage of max — roughly 90% for triples, 80% for sets of 6–8, 70% for higher-rep work. The tool lists those so you can pick working weights for your strength-and-conditioning around BJJ. Accuracy is best from sets of one to about ten reps; beyond that the estimate drifts, so test with a heavier set.

Frequently asked questions

How accurate is a 1RM calculator?
Quite accurate from a hard set of 1–10 reps — usually within a few percent. Accuracy falls off above ten reps, so use a heavier set for a better estimate.
What's the difference between Epley and Brzycki?
They're two formulas for the same job. They agree closely at low reps and diverge at higher reps, so averaging them gives a sensible middle estimate.
Should I test my actual max?
Rarely necessary, and never without a full warm-up and a spotter. For programming around BJJ, an estimate from a submaximal set is safer and plenty accurate.