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1RM explained

One rep max calculator

Estimate your one rep max without a risky max attempt. Enter how much weight you lift for multiple reps and instantly see your estimated 1RM plus the matching training percentages.

Calculate your 1RM

Use a set you performed to (near) muscle failure, with a maximum of 12 reps.

What is your 1RM?

Your 1RM (one rep max) is the maximum weight you can lift exactly once with good technique. It is the standard measure of maximal strength and the starting point for virtually every serious strength program: training loads are usually prescribed as a percentage of your 1RM.

How the calculation works

A true max attempt is demanding and not without risk. That is why we estimate your 1RM from a submaximal set using the Epley formula, one of the most widely used and validated estimation formulas. The fewer reps you enter, the more accurate the estimate.

1RM = weight × (1 + reps / 30)

How to use your 1RM in training

Your 1RM determines your training loads per goal. Lifting heavy for few reps primarily builds maximal strength, while lighter sets with more reps target muscle growth and muscular endurance.

  • Maximal strength: 85-95% of your 1RM, 1-5 reps per set.
  • Muscle growth (hypertrophy): 65-80% of your 1RM, 6-12 reps per set.
  • Muscular endurance: 50-65% of your 1RM, 12 or more reps per set.
  • Retest your 1RM every 6 to 12 weeks and adjust your training loads accordingly.

Caveats

Estimation formulas are most reliable for compound lifts such as the squat, bench press and deadlift, and for sets of up to about 10 reps. Only perform max attempts with a proper warm-up, correct technique and a spotter or safety pins.