One-Rep Max
Calculator
Enter a weight and the reps you hit with good form. Get an estimated 1RM and a load table so you can program every session as a percentage of your max.
Your set
Estimated 1-rep max
Training loads
How this works
Methodology reviewed July 2026Your one-rep max (1RM) is the most weight you can lift for a single rep. Rather than test it directly — which is risky and fatiguing — this tool estimates it from a set you've already done, using established rep-max equations, then builds a percentage-load table so you can program every session off the estimate.
Epley: 1RM = weight × (1 + reps / 30)
Brzycki: 1RM = weight × 36 / (37 − reps)
Training loads = 1RM × target % (50%–95%)
Weight lifted · Reps completed
Estimated 1RM · Percentage-of-1RM load table
- Estimates are most accurate in the ~2–10 rep range and drift at very high reps.
- The set was taken close to failure with good form.
- Different equations give slightly different numbers; treat the 1RM as an estimate, not a certified max.
- Accuracy falls as reps rise — a 20-rep set is a poor predictor.
- Warm up, use a spotter or safeties for heavy attempts, and don't chase a number at the cost of form.
This calculator is for educational purposes only and is not medical advice, diagnosis, or treatment. Results are estimates based on published formulas and population averages — your individual values may differ. Nothing here is calculated on a server: everything runs in your browser and no data is stored or sent anywhere. Always consult a qualified clinician before making health, medication, or training decisions.