Estimate your 1RM for any lift using Epley, Brzycki, and Lombardi formulas.
One Rep Max Calculator converts the load and repetitions from one set into three estimated maximums: Epley, Brzycki, and Lombardi. Each equation projects the set differently, so its result may not match the others. Enter the repetitions completed continuously at that load, not the total repetitions performed across several sets. The estimate is most meaningful when the set reflects your actual repetition capacity; stopping well before failure can produce a projected 1RM that is too low.
A concrete input and expected output from the current implementation.
Input
Weight lifted: 60 kg; repetitions: 10
Expected output
Epley: 80 kg; Brzycki: 80 kg; Lombardi: approximately 75.54 kg
Epley gives 60 x (1 + 10/30) = 80, and Brzycki gives 60 x 36/(37 - 10) = 80. Lombardi gives 60 x 10^0.10 = 75.5355..., which rounds to 75.54.
For load w and repetition count r, the calculator evaluates Epley as w x (1 + r/30), Brzycki as w x 36/(37 - r), and Lombardi as w x r^0.10. Each formula scales the entered load. A load entered in pounds produces estimates in pounds, while a load entered in kilograms produces estimates in kilograms.
Epley increases its multiplier linearly with repetitions, Brzycki uses a denominator that decreases as the repetition count rises, and Lombardi applies a tenth-power curve. The three figures are alternative model estimates, not measurements of different kinds of strength. Their spread shows how strongly the selected equation affects the projection for that set.
Their equations have different forms but can produce the same multiplier at particular repetition counts. At 10 repetitions, Epley's multiplier is 1 + 10/30, or 4/3, while Brzycki's is 36/(37 - 10), also 4/3. Matching results at one input do not make the formulas equivalent for other repetition counts.
Not automatically. A calculated 1RM is a projection from one set, not confirmation that the weight can be lifted safely or successfully. Readiness, fatigue, technique, equipment, and spotting conditions still matter. Use suitable warm-up attempts and safety equipment, and reduce the target when the estimate conflicts with recent lifting performance.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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