One Rep Max Calculator — Test Your 1RM Without Risking It

Enter a weight you can lift for reps — get your estimated one-rep max plus the classic percentage chart (70%, 80%, 90%…) for programming any strength block.

Quick answer: Free 1RM calculator: estimate your one-rep max from any weight × reps set using Epley and Brzycki formulas, plus a full percentage training chart. Lift smarter, test safer.

Weight lifted Reps

–1RM (Epley)

–1RM (Brzycki)

How to use

Enter weight & reps — your best hard set (most accurate at 1–8 reps).
Compare formulas — Epley and Brzycki estimates shown side by side.
Use the % chart — pick training weights by goal: strength, hypertrophy or endurance.

About this tool

Actual 1RM attempts are the riskiest lifts in the gym. The smarter way: take a hard set of 1–10 reps and estimate the max with the two validated formulas — Epley (w × (1 + reps/30)) and Brzycki (w × 36/(37 − reps)), which agree closely under 10 reps. You also get the percentage chart powerlifters program with: 90% for heavy singles, 80% for strength, 70% for hypertrophy volume, 60% for speed work — so the estimate turns directly into a training plan.

FAQ

How accurate is a calculated 1RM?

Within a few percent when based on a true hard set under 10 reps — accuracy drops for high-rep sets (muscular endurance skews the math).

Why estimate instead of testing for real?

Real 1RM attempts are injury-risk moves with fatigue costs; estimating from reps gives 95% of the information at 10% of the risk.

What percentage should I train at?

Strength ≈ 80–90% for low reps, hypertrophy ≈ 65–80% for 6–12 reps, endurance ≤ 65% — the chart maps it all from your max.

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One Rep Max Calculator — Test Your 1RM Without Risking It

How to use

About this tool

FAQ

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