One-Rep Max Calculator
Estimate your one-rep max (1RM) from a set you actually did — enter the weight and reps, and get your estimated max plus a training-percentage table for planning your working sets. Uses the Epley and Brzycki formulas. No need to risk a true max attempt.
Training percentages
FAQ
What is a one-rep max (1RM)?
The most weight you can lift for a single rep. Rather than testing it directly (risky), you estimate it from a multi-rep set — which is what this tool does.
How is 1RM estimated?
From your weight and reps, averaging two known formulas — Epley (w × (1 + reps/30)) and Brzycki (w × 36 / (37 − reps)) — which agree closely in the 1-10 rep range.
How accurate is it?
Good for low-to-moderate reps (~1-10); accuracy drops at 15+ reps. Use your lowest-rep set and treat it as a guide.
What are the training percentages for?
Programs prescribe loads as a % of 1RM (e.g. 5 reps at 85%). The table turns your max into working weights.
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