Health calculator

One-Rep Max Calculator

Estimate one-rep max strength from a lifted weight and repetitions.

Formula1RM = weight x (1 + reps / 30)

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.

FAQ5 common questions for this calculator.

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?+

For the One-Rep Max Calculator, 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?+

For the One-Rep Max Calculator, enter a lifted weight and repetitions. Keep the units consistent with the calculator fields and compare your setup with the worked example on the page.

How accurate is the One-Rep Max Calculator?+

One-Rep Max Calculator is only as accurate as the a lifted weight and repetitions entered. It applies the Epley 1RM formula shown on this page, then rounds for readability. Treat the output as screening guidance rather than a diagnosis.

What should I check before using the One-Rep Max Calculator result?+

For the One-Rep Max Calculator, check a lifted weight and repetitions, unit choices, and whether the calculator's assumptions fit the person being assessed. Use the result as screening or planning context, not as a diagnosis.

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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. 1

    Enter your details

    Enter a lifted weight and repetitions, then complete any other fields shown in the calculator.

  2. 2

    Check the calculation

    Review the result alongside the epley 1RM formula: 1RM = weight x (1 + reps / 30).

  3. 3

    Compare scenarios

    Change one or more inputs to see how they affect the one-Rep Max Calculator result before you use the estimate.