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All calculatorsMethodology

One Rep Max Calculator

Estimate a one-rep max for deadlift, squat or bench from weight and reps with five published formulas, their average, and a 50–95% percentage table.

Interactive calculator · Method ONE-REP-MAX-1.0 · Last reviewed: 2026-11-04

Calculate your scenario

Epley = w × (1 + r ÷ 30); Brzycki = w × 36 ÷ (37 − r); Lombardi = w × r^0.10; Lander = 100 × w ÷ (101.3 − 2.67123 × r); O’Conner = w × (1 + 0.025 × r).

Your inputs

Try an example

Default worked example. Edit the inputs to calculate your scenario.

Default worked example

Average estimate 257.8 lb
Epley 262.5 lb
Brzycki 253.1 lb
Lombardi 264.3 lb
Lander 255.8 lb
O’Conner 253.1 lb

Average of five estimates for 225 lb × 5 reps = (262.5 + 253.1 + 264.3 + 255.8 + 253.1) ÷ 5 = 257.8 lb.

How to use the calculator

Enter the weight and the number of clean reps from a hard set, choose pounds or kilograms, and read the average and the individual formulas. The table shows percentages of the average.

What the result means

A 225 lb set of 5 gives estimates from about 253.1 to 264.3 lb, averaging about 257.8 lb.

Formula and units

Epley = w × (1 + r ÷ 30); Brzycki = w × 36 ÷ (37 − r); Lombardi = w × r^0.10; Lander = 100 × w ÷ (101.3 − 2.67123 × r); O’Conner = w × (1 + 0.025 × r). The average is the plain mean of the five. By convention a single rep returns the weight lifted for every formula (Epley alone would otherwise add 3.3%).

Worked examples

225 lb for 5 reps: Weight lifted: 225 lb or kg; Reps completed (1–12): 5 reps; Unit: lb.
Example result: Average estimate: 257.8 lb; Epley: 262.5 lb; Brzycki: 253.1 lb; Lombardi: 264.3 lb; Lander: 255.8 lb; O’Conner: 253.1 lb.

100 kg for 10 reps: Weight lifted: 100 lb or kg; Reps completed (1–12): 10 reps; Unit: kg.
Example result: Average estimate: 130.3 kg; Epley: 133.3 kg; Brzycki: 133.3 kg; Lombardi: 125.9 kg; Lander: 134.1 kg; O’Conner: 125 kg.

Limitations and common mistakes

An estimate from one set, not a measured max, a prescribed lift or a training program. The formulas were fitted to sets of roughly 10 reps or fewer to failure; reps above 10, sets not taken near failure, and fatigue all make them less reliable. Entries are limited to 1–12 reps.

Entering a warm-up set that stopped well short of failure; the formulas assume the last rep was close to the limit.

Sources and assumptions

Method ONE-REP-MAX-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.