One Rep Max Calculator
1RM via Epley, Brzycki and Lombardi.
Most accurate for 1–10 reps.
How to Use
- Choose kg or lb.
- Enter the weight you lifted and the reps performed.
- See your estimated 1RM and training percentages.
Calculation Method
Three established estimators, averaged:
- Epley: 1RM = w × (1 + reps/30)
- Brzycki: 1RM = w × 36 / (37 − reps)
- Lombardi: 1RM = w × reps^0.10
Accuracy is highest at 1–10 reps. Training percentages are taken from the averaged 1RM.
Source: Epley (1985), Brzycki (1993), Lombardi (1989) formulas
Examples
Estimated 1RM ≈ 113–116 kg (avg ≈ 115 kg)
Estimated 1RM ≈ 99–101 kg
Frequently Asked Questions
Yes — estimating from a submaximal set avoids the injury risk of a true max attempt. Always warm up and use a spotter for heavy lifts.
Each was derived from different populations and lifts. Averaging them gives a robust working estimate.
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Health & Fitness Disclaimer
The health and fitness calculations provided are estimates only and should not replace professional medical advice. Individual health needs vary based on medical conditions, medications, personal goals and activity level. Consult with a healthcare provider, registered dietitian, or certified fitness professional before making significant changes to your diet or exercise routine. Not medical advice.
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Last updated: May 24, 2026