One Rep Max Calculator

Estimate your 1RM using the Epley and Brzycki formulas. Enter your lift weight and reps to get started.

One Rep Max Calculator

Weight Lifted

Reps Performed

Understanding Your One Rep Max

Your one rep max (1RM) is the heaviest weight you can lift for a single repetition with correct form. It's the most common benchmark for measuring absolute strength and serves as the foundation for percentage-based training programs used by powerlifters, Olympic lifters, and strength athletes worldwide.

Method and example

For 60 kg lifted 8 times, Epley gives 60 × (1 + 8 / 30) = 76.0 kg. Brzycki gives 60 × 36 / (37 − 8) = 74.5 kg. The percentage table uses Epley, so its 80% row is 60.8 kg. That does not guarantee eight repetitions at that load.

The equations work in either kg or lbs and return the same unit you enter. Select the unit before entering the load. Values are rounded only for display. For one rep, we display the recorded load without extrapolation.

Using a recorded set

Enter 1–10 whole repetitions from one set of the same exercise. Estimates depend on effort and technique; a set stopped well before your repetition limit may underestimate your capacity. You do not need to attempt a maximal lift to use this tool. Discuss testing or training loads with a qualified coach.

Research and limitations

Reynolds et al. (2006) compared repetition tests in bench press and leg press. A 2003 study of collegiate football players evaluated prediction equations using bench press sets. These specific populations and exercises do not establish universal accuracy. Agreement between two formulas is not proof that either matches your measured maximum.

Disclaimer: This calculator is for informational purposes only and is not a substitute for professional coaching advice. Always use proper form and a spotter when lifting heavy weights.

Frequently Asked Questions

What is a one rep max (1RM)?

The greatest load you can complete for one repetition of a specific exercise with correct technique. This calculator estimates it from a recorded set; it does not measure your maximum.

How do the formulas differ?

Epley uses weight × (1 + reps / 30); Brzycki uses weight × 36 / (37 − reps). For 2–9 reps, this Epley form gives the higher number. They agree at 10 reps. Neither is guaranteed to be more accurate for every exercise or person.

Why is the calculator limited to 10 reps?

This is a conservative limit for this tool. Research on bench press and leg press found lower-repetition tests more predictive than higher-repetition tests. It does not guarantee accuracy below the limit.

What does entering one rep mean?

Both cards show the load you entered. Completing one rep does not establish that it was your maximum; no extra weight is added to that recorded lift.

How should I interpret the percentage table?

It multiplies the Epley estimate by each percentage, or uses the recorded load for a single rep. The rows are not guaranteed repetition targets or a personalized training plan.

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