Calci

One Rep Max Calculator

Estimate your one-rep max (1RM) from a weight and rep count you've actually lifted, using your choice of the Epley, Brzycki, or Lombardi formula. Get training weights at 95%, 90%, 85%, 80%, 75%, and 70% of that estimate.

Units

Formulas become less reliable above about 10 reps.

Estimated 1RM
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95% Intensity
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90% Intensity
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85% Intensity
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80% Intensity
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75% Intensity
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70% Intensity
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Assumptions

Sources

Why three different formulas give three different answers

Epley, Brzycki, and Lombardi were each derived differently: Epley came from a poundage chart published for university athletes, Brzycki from a practitioner article built around a hyperbolic relationship between reps and percentage of max, and Lombardi from a strength training manual using a power function. None came from a single definitive study, and none perfectly matches every lifter or every exercise. For most people testing in the 1 to 8 rep range, the three formulas typically land within a few percent of each other. Picking one and staying consistent matters more than which one you pick.

Why accuracy falls apart at higher reps

Every one of these formulas assumes a fixed relationship between reps performed and percentage of 1RM, but that relationship is not actually fixed: it varies by exercise, by how trained someone is, and by how close to true muscular failure the set really was. The further a test set is from a true 1RM, for example 15 or 20 reps instead of 3 to 5, the more that assumption breaks down, and the wider the gap grows between what the formula predicts and what could actually be lifted once.

Worked example

A 185 lb bench press for 5 reps, using the Epley formula.

Epley: 1RM = 185 x (1 + 5/30) = 185 x 1.1667 = 215.8, rounded to 216 lb. At 85% intensity (216 x 0.85 = 183.6), that's about 183 lb, which the reference table says you should be able to complete for about 6 reps.

Frequently asked questions

Does this work for the bench press specifically?

Yes, and it tends to be most reliable there: the classic research comparing these formulas against measured 1RMs found strong correlations for the bench press specifically, since that's the lift most of the original formulas were developed and tested on.

Is this as accurate for squats as it is for the bench press?

Not quite. Comparison studies that tested these formulas across the bench press, squat, and deadlift found accuracy varies by exercise, since squats involve more muscle mass and a different fatigue pattern than the upper-body pressing movement the formulas were originally built around. Treat a squat estimate as a slightly rougher ballpark than a bench press estimate.

Why might my estimated deadlift max feel off?

Research directly comparing these formulas across lifts found they consistently underestimated the deadlift 1RM more than the bench press or squat. If your real deadlift max has historically run higher than what a rep-based estimate suggests, that's a documented pattern, not a sign you're doing something wrong.

How is this different from actually testing my 1RM?

An estimate uses a formula and a submaximal set to predict a number; an actual test has you lift a real single maximal rep under controlled conditions. Estimates are useful for programming without the fatigue and injury risk of frequent max testing, but they carry the error margin of whichever formula produced them, especially outside the 1 to 8 rep range.

How does this relate to RPE (rate of perceived exertion)?

Both are ways of estimating how close a set was to a true maximum. RPE relies on your own sense of remaining reps in reserve, while this calculator relies on a fixed formula applied to your actual reps completed. Both assume the set was taken close to failure: if it wasn't, an RPE-based estimate and a formula-based one will both run high, for the same underlying reason.

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