Health calculator
One-Rep Max Calculator
Estimate one-rep max strength from a lifted weight and repetitions.
Formula
Epley 1RM formula
Strength estimates are approximate. Use proper coaching and safety equipment for max attempts.
1RM = weight x (1 + reps / 30)
100 kg for 5 reps estimates a 1RM of about 117 kg.
FAQs
Which formula is used?+
The main result uses the Epley estimate and also shows a Brzycki estimate.
How does the One-Rep Max Calculator calculate the result?+
It uses the Epley 1RM formula: 1RM = weight x (1 + reps / 30). 100 kg for 5 reps estimates a 1RM of about 117 kg.
What information do I need to use the One-Rep Max Calculator?+
Estimate one-rep max strength from a lifted weight and repetitions.
How accurate is the One-Rep Max Calculator?+
One-Rep Max Calculator applies the formula and assumptions shown on this page. Results may be rounded for readability, so verify changing rates, thresholds, medical guidance, or legal rules with the cited source or a qualified professional.
What should I check before using the One-Rep Max Calculator result?+
Check that the units, dates, rates, and assumptions match your situation. Change one input at a time to understand which values have the largest effect on the result.
Health guide
How to use the One-Rep Max Calculator
Estimate one-rep max strength from a lifted weight and repetitions. The page also explains the epley 1RM formula and shows a practical example: 100 kg for 5 reps estimates a 1RM of about 117 kg.
- 1
Enter your details
Enter a lifted weight and repetitions, then complete any other fields shown in the calculator.
- 2
Check the calculation
Review the result alongside the epley 1RM formula: 1RM = weight x (1 + reps / 30).
- 3
Compare scenarios
Change one or more inputs to see how they affect the one-Rep Max Calculator result before you use the estimate.
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