What are the sources for one-rep max calculations?

Brzycki is weight × 36 / (37 − reps), from Matt Brzycki, Strength testing—predicting a one-rep max from reps-to-fatigue, Journal of Physical Education, Recreation & Dance, 1993, as walked through by Mayo and Kravitz: 75 lb for 9 reps estimates 96 lb, https://www.unm.edu/~lkravitz/Article%20folder/musassess.html. Epley is weight × (1 + reps / 30) for 2–10 reps, from Boyd Epley, 1985, with the coefficient table and the 200 lb × 5 comparison on http://www.weightrainer.co.uk/training/coefficients.html.

One Rep Max Calculator

Epley and Brzycki estimates from a weight and the reps you completed. Both are shown. An estimate, not a diagnosis.

Weight unit

Smart Tips

• Stop the set with good form. These formulas assume the reps went to fatigue, not a casual set.

• Use 1 to 10 reps. Brzycki’s published walkthrough is for failure at 10 repetitions or fewer.

• At one rep, both results are the weight you lifted.

• From two to ten reps, Epley is weight × (1 + reps / 30). Brzycki is weight × 36 / (37 − reps).

• A predicted max is not a weight to load for a single. Stop if something hurts.

• The unit switch only labels pounds or kilograms. It does not change the arithmetic.

The Formula

Epley = weight × (1 + reps / 30)
Brzycki = weight × 36 / (37 − reps)

Epley Boyd Epley, 1985
Used here for 2–10 reps

Brzycki Matt Brzycki, 1993
weight × 36 / (37 − reps)

1 rep Both return the weight
A completed single is the max

10 Upper rep cap
The fits were not built for higher reps

200 for 5 reps is 225 by Brzycki (200 × 36 / 32) and 233.3 by Epley (200 × (1 + 5/30)). 75 for 9 reps is 96.4 by Brzycki, which rounds to the published 96 lb example.

Key Insights

Both stay on screen

Epley and Brzycki are different fits. The page shows both instead of hiding one behind a toggle.

Not a load to attempt

The number is a prediction from a submaximal set. It is not a prescription to try that weight for one rep.

Ten-rep cap

The Brzycki walkthrough is for failure at 10 reps or fewer. Reps above 10 are rejected.

No strength rank

There is no elite, novice, or leaderboard label. The result is only the two estimates.

Medical Disclaimer

Estimate only: This page is an estimate, not a diagnosis, a lab test, or a treatment plan.

Not a weight to attempt: Stop on pain. This is not medical clearance to lift, and it is not a measured one-rep max.

Frequently Asked Questions

Epley and Brzycki are two published fits from the same weight and reps. They do not agree. Both stay on the page so you can see the spread.

A completed single is the one-rep max. Both formulas return that weight. From two reps up, Epley uses weight × (1 + reps / 30).

The Brzycki method described for this estimate is for a set that fails at 10 repetitions or fewer. Epley’s coefficient tables are also shown through 10 reps. A higher rep count is rejected.

No. The formulas are the same in either unit. The switch only changes the label on the result. Enter the weight in the unit you select.

No. The result is a prediction, not a weight to load. Warm up, use a spotter for heavy free-weight attempts, and stop on pain. This page is not a clearance to lift.

Brzycki is weight × 36 / (37 − reps), from Matt Brzycki, “Strength testing—predicting a one-rep max from reps-to-fatigue,” Journal of Physical Education, Recreation & Dance, 1993, as walked through by Mayo and Kravitz: 75 lb for 9 reps estimates 96 lb, Muscular Assessment. Epley is weight × (1 + reps / 30) for 2–10 reps, from Boyd Epley, 1985, with the coefficient table and the 200 lb × 5 comparison on The WeighTrainer.

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Epley

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Brzycki

Weight lifted

Note:Both numbers are predictions from the reps you entered. A completed single is returned as that weight. This is an estimate, not a diagnosis, and not a weight to attempt.