What is the One Rep Max Calculator?
Estimate your one-rep max from a weight and reps performed, using the Epley and Brzycki formulas. Our health and fitness calculators use validated, published equations — such as Mifflin-St Jeor for metabolic rate and the U.S. Navy method for body fat — to give you a solid starting point for training and nutrition.
How to use the One Rep Max Calculator
- Enter your weight lifted, your reps completed.
- Results update automatically as you type; you can also press Calculate.
- Read the output: epley 1rm, brzycki 1rm, training loads.
- Use the 📊 chart to see the result visually, then copy or share it.
Formula and method
Worked example
With weight lifted = 100 kg/lb, reps completed = 5, the One Rep Max Calculator returns epley 1rm: 116.7; brzycki 1rm: 112.5.
Tips for better results
- Equations estimate population averages; your individual numbers may differ.
- Track trends over weeks rather than reacting to a single reading.
- Pair calculators with professional guidance for medical conditions, pregnancy or major diet changes.
⚠️ This tool provides general information and is not medical advice. It is not a substitute for diagnosis or treatment by a qualified healthcare professional.
Frequently asked questions
What does the One Rep Max Calculator do?
Estimate your one-rep max from a weight and reps performed, using the Epley and Brzycki formulas.
How is it calculated?
The One Rep Max Calculator uses this method: Epley: 1RM = W × (1 + reps/30); Brzycki: 1RM = W × 36 ÷ (37 − reps).
Can you show an example?
With weight lifted = 100 kg/lb, reps completed = 5, the One Rep Max Calculator returns epley 1rm: 116.7; brzycki 1rm: 112.5.
Is the One Rep Max Calculator accurate?
It uses standard published formulas and is tested against known values, but results are estimates for guidance. This tool provides general information and is not medical advice. It is not a substitute for diagnosis or treatment by a qualified healthcare professional.
Is this tool free and private?
Yes — the One Rep Max Calculator is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.
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