Your one-rep max (1RM) is the heaviest weight you can lift for a single rep with proper form. Testing a true 1RM can be risky, so this calculator estimates it from a lighter, safer set using the Epley formula, a method widely used by strength coaches. Pick your lift, enter the weight and reps from a recent set, and you will get your estimated 1RM plus a full percentage chart for programming your training. For the bigger picture of your fitness, check out our TDEE Calculator, BMR Calculator, or Calories Burned Calculator.

One-Rep Max (1RM) Calculator





Estimated One-Rep Max
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% of 1RM Weight Typical Reps
Personalized Recommendation

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Person performing a heavy barbell squat in a power rack while testing their maximum single-rep strength
Your one-rep max reflects the heaviest weight you can lift for a single, maximal-effort rep, a key benchmark for strength training.

How This Calculator Works

This calculator uses the Epley formula, one of the most widely used methods for estimating one-rep max: 1RM = weight x (1 + reps / 30). It works best when you use a set of 1 to 12 reps taken close to failure. The percentage chart then shows how much weight to use for common training percentages, a standard tool for planning strength programs.

Disclaimer: This calculator provides an estimate based on a standard strength formula and is not a substitute for professional coaching. Always warm up properly and use a spotter or safety equipment when attempting heavy lifts. Consult a fitness professional before starting a new strength program.