1RM Formulas & Calculations

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1RM Formulas & Calculations

Every equation lifters argue about — Epley, Brzycki, Lombardi, and the rest — compared head to head with the research, plus percentage charts and the practical math behind your training weights.

The Guides

1

7 One Rep Max Formulas Compared

Epley vs Brzycki vs Lombardi and four more — the equations, the research, the 10-rep crossover, and which formula to trust for your lift.

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2

The Epley Formula Explained

The most widely used 1RM equation — how it works, worked examples in lb and kg, when it’s most accurate, and its limits.

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3

The Brzycki Formula Explained

The research community’s favorite — honest at 1 rep, best for bench press, but never use it past 12 reps. Here’s why.

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4

1RM Percentage Chart

The complete % of 1RM table — turn your max into training weights, plus Prilepin’s volume chart and the training max trick.

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Formula Questions, Answered

Which 1RM formula is most accurate?
No single formula wins everywhere. Epley is most validated for squats, Brzycki for low-rep bench press, Mayhew for moderate-rep bench. The average of all seven is the most defensible single number — which is what our calculator shows.
Why do different calculators give different numbers?
They use different equations. From the same set, the seven major formulas can disagree by 6+ kg at 5 reps and 30+ kg at 15 reps. Details in the full comparison.
Can I do the math in my head?
Epley, yes: multiply weight × reps, divide by 30, add the weight. The others need a calculator — or just use ours.

Next section: ← Back to all guides · 1RM Basics · Once you know the formulas, the Strength Standards section tells you where your numbers actually rank. (Coming soon.)