Repetition maximum

RM stands for Repetition Maximum. It is a term that combines weight and repetition count. Your 1RM is a weight you can lift once but cannot lift twice with the same form. Your 5RM is a weight that brings you to your limit on the fifth repetition, and your 10RM is a weight that brings you to your limit on the tenth repetition.

The term captures the relationship in which the heavier the weight, the fewer repetitions you can perform. So an expression such as "bench press 60kg 5RM" clearly conveys the weight, target repetition count, and level of difficulty all at once. RM is determined separately for each movement. Having a high squat 1RM does not necessarily mean your bench press 1RM is also high, and even for the same person, it varies slightly from day to day depending on readiness and skill level.

Measuring it directly. After warming up thoroughly with a light weight, gradually increase the weight and perform one lift at a time. The last weight you successfully lift before reaching a weight you can no longer lift is your 1RM. Because this involves heavy weights, it is best done with a spotter in a setting equipped with safety devices.

Estimating it with a formula. In practice, a common approach is to lift a less demanding weight several times and enter the result into a formula to estimate 1RM. One widely used method is the Brzycki formula: multiply the weight lifted by 36, then divide by (37 − number of repetitions). For example, if you lift 80kg five times, the calculation is 80 × 36 ÷ 32 = approximately 90kg. The Epley formula (weight × (1 + repetitions ÷ 30)) is also widely used.

A study comparing seven prediction formulas with actual 1RM values in the bench press, squat, and deadlift (LeSuer et al., 1997) found that the difference between estimated and actual values increased as the repetition count rose. Estimates are therefore more reliable when calculated from a set completed within ten repetitions.

Programs list both the percentage of 1RM (%1RM) and the number of repetitions. The broad framework outlined in the American College of Sports Medicine's position stand is as follows.

• 1–5 repetitions (approximately 85% of 1RM or above) — When the goal is to increase maximal strength
• 6–12 repetitions (approximately 67–85% 1RM) — When the goal is muscle hypertrophy, or increasing muscle size
• 15 or more repetitions (below approximately 67%) — When the goal is to improve muscular endurance, or the ability to sustain effort

Later research has described overlap between these ranges. For muscle growth, the findings suggest that taking sets close to failure can produce similar growth across a fairly wide range of weights. Research continues to favor heavier weights specifically for maximal strength. In either case, how close today's set came to your limit matters.

• People who have received their first gym program and wonder what '%1RM' means
• People deciding how much weight to use for squats, bench presses, and deadlifts
• People who want to use numbers to check whether they are stronger than they were a few weeks ago
• People planning their training for a sport in which performance records are compared

• You do not have to measure your 1RM directly. Estimating it from a weight you can lift for 3–5 repetitions can be sufficient for planning.
• Intensity can also be set by 'how many more reps you could have done.' Repetitions in reserve is your own estimate of how many repetitions you had left at the end of a set, while rating of perceived exertion scores how hard that set felt. Whereas RM is a label attached to a weight, these two scales reflect your readiness on the day.
• Increase the weight gradually. Separate from how you determine RM, the principle of gradually increasing weight or repetitions is called progressive overload.
• If your form breaks down, that repetition does not count. RM assumes repetitions performed with proper form.
• Keep separate records for each movement. Record your squat, bench press, and deadlift 1RM separately.