Your ten-rep max (10RM) is the maximum weight you can lift for exactly ten repetitions with proper form. This metric is particularly valuable for hypertrophy training, as the 8-12 rep range is widely considered optimal for building muscle size. Knowing your 10RM helps you select the right weights for your working sets, ensuring you're training with enough intensity to stimulate muscle growth without going to failure on every set. This calculator uses your performance on a recent set to estimate your 10RM.