Your one-rep max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise. It's the gold standard for measuring your maximal strength. Knowing your 1RM is essential for designing effective strength training programs, as many programs base their intensity (the weight you lift) on a percentage of your 1RM. This calculator allows you to safely estimate your 1RM without the risk of injury that comes with performing a true one-rep max lift.