One Rep Max Calculator
Calculate your estimated one-repetition maximum (1RM) for any lift using multiple validated formulas.
Input Parameters
Results
One Rep Max (1RM)
The 1RM is the maximum weight you can lift for a single repetition. It is used to set training loads. For hypertrophy (muscle growth), train at 65–80% 1RM for 8–12 reps. For strength, use 85–95% 1RM for 1–5 reps. Always warm up and use a spotter for heavy lifts.
What is the One Rep Max (1RM) Calculator?
The One Rep Max (1RM) Calculator is an essential strength training tool used by weightlifters and athletes. It safely estimates the absolute maximum amount of weight you can lift for a single repetition without actually attempting a dangerous, heavy single lift.
How It Works (Formula)
We utilize the highly regarded Epley formula, which calculates your theoretical maximum by factoring in the weight you lifted and the number of repetitions you successfully completed to failure.
$$ \text{1RM} = W \times \left(1 + \frac{R}{30}\right) $$
The Epley formula, where W is weight and R is repetitions.
How to Use It
Perform a set of an exercise (like bench press or squats) to muscular failure. Enter the weight you used and the number of reps you achieved. The calculator will output your 1RM, as well as percentage breakdowns (e.g., 80% of 1RM) for programming your future workouts.