One-Rep Max Calculator

How this one-rep max calculator works

A one-rep max (1RM) is the most weight you can lift for a single, full-range rep with good form. Testing it directly is fatiguing and carries injury risk, so most lifters estimate it from a lighter set of 2 to 10 reps instead.

This calculator runs your weight and rep count through four published formulas — Epley, Brzycki, Lombardi, and O'Conner — and averages them. Each formula assumes a slightly different relationship between reps and fatigue, so they agree closely at low rep counts (2 to 5) and drift apart above 10 reps, which is why estimates get less reliable the higher your rep count goes.

The 90%, 80%, 70%, and 60% rows are your calculated 1RM translated into common training percentages, useful for programming top sets, back-off sets, or a percentage-based block.

For a bench-only or single-lift version of this same math, see the bench press calculator, squat max calculator, or deadlift max calculator. If your program is written in kilograms, the kg to lbs converter will get your numbers into whichever unit you selected above.

Where these numbers come from

The formulas and default values in this calculator are based on:

• Epley (1985) 1RM prediction formula
• Brzycki (1993) 1RM prediction formula
• Lombardi (1989) 1RM prediction formula
• O'Conner et al. (1989) 1RM prediction formula

These are planning estimates for training purposes. Check with a coach, trainer, or physician before starting a new program or maxing out.