One-Rep Max (1RM) Calculator
Calculate your one-rep max using 6 validated formulas (Epley, Brzycki, Mayhew, Lombardi, O'Conner, Wathan). Get percentage-based training zones. Free, instant.
All calculations run instantly in your browser. No data is sent to any server.
Disclaimer: Results are for informational purposes only and do not constitute medical advice, diagnosis, or treatment. Consult a qualified healthcare professional for personal guidance.
Why Estimate 1RM Without Testing It
Actual 1RM testing carries injury risk, requires significant warm-up time, and is best reserved for experienced lifters with a spotter. Submaximal testing (lifting 80–90% of your estimated 1RM for 3–5 reps) is safer and nearly as accurate. The formulas below are validated for sets up to approximately 10 reps; accuracy degrades at higher rep ranges because endurance becomes a confounding factor.
Training Zones
| Goal | % of 1RM | Rep range |
|---|---|---|
| Maximal strength | 90–100% | 1–3 |
| Strength-hypertrophy | 75–85% | 5–8 |
| Hypertrophy | 67–75% | 8–12 |
| Muscular endurance | 50–67% | 15+ |
FAQs
Most accurate formula?
Epley and Brzycki perform comparably for 1–10 rep sets. Use 3–5 rep sets for best accuracy. Accuracy decreases with higher rep counts.
Training percentages?
90–100% for maximal strength, 75–85% for strength-hypertrophy, 67–75% for hypertrophy, 50–67% for endurance (NSCA guidelines).