One Rep Max Calculator
Calculate your maximum single repetition strength with scientifically proven formulas
What is a One Rep Max Calculator?
A One Rep Max (1RM) calculator is an essential strength training tool that estimates the maximum weight you can lift for a single repetition based on your performance at higher repetitions. Instead of risking injury by attempting a true maximum lift, this calculator uses scientifically validated formulas to predict your 1RM from safer submaximal lifts, typically performed between 2-20 repetitions.
Our advanced 1RM calculator incorporates seven proven formulas including Epley, Brzycki, Lander, Lombardi, Mayhew, O'Conner, and Wathan equations, each developed through extensive research with powerlifters, weightlifters, and strength athletes. These formulas account for different training backgrounds and lifting styles, providing the most accurate strength predictions available.
Essential for powerlifters planning competition attempts, bodybuilders designing progressive overload programs, strength coaches programming training cycles, athletes tracking strength gains, and fitness enthusiasts setting realistic goals. The calculator also provides percentage-based training zones, helping you determine optimal loads for different rep ranges and training objectives while minimizing injury risk.
Weight
Lifted weight
Reps
Repetitions performed
1RM
Maximum single rep