What does the term '1RM' stand for in strength training?

In strength training, 1RM stands for one-rep maximum: the heaviest weight a person can lift for one complete repetition of an exercise.

A one-rep maximum is a practical measure of maximal strength. Coaches often use it to prescribe training loads as percentages—for example, sets performed at 70% or 80% of an athlete’s 1RM. The value is exercise-specific: someone can have different 1RMs for the bench press, squat, deadlift, and other movements.

A true 1RM is normally found by gradually increasing the weight until the lifter can complete one repetition with proper form but cannot successfully lift the next heavier load. Because maximal attempts can be demanding, a spotter and careful technique are important, especially for beginners.

People also estimate 1RM from a lighter set of multiple repetitions using formulas. Those estimates are quicker and often safer, but they can differ from the actual maximum. “One-repetition max” is simply another common wording for the same concept.