What is the One Rep Max Calculator?
Estimate your one-repetition maximum from a weight you can lift for several reps.
Enter weight lifted and repetitions and the One Rep Max Calculator returns one-rep max (Epley), brzycki estimate, 85% of one-rep max and 70% of one-rep max. Results update as you type, and nothing you enter leaves your device.
How it is calculated
Epley: 1RM = weight × (1 + reps ÷ 30)
How to use it
- Enter weight lifted in kg.
- Enter repetitions in reps.
- Read one-rep max (Epley) in the results panel. It updates as you type.
- Change any value to compare scenarios, or use Share to send the result as a link.
Worked example
Common questions
What formula does the One Rep Max Calculator use?
It uses: Epley: 1RM = weight × (1 + reps ÷ 30).
What do I need to use the One Rep Max Calculator?
You need weight lifted and repetitions. Sensible starting values are filled in so you can see how it works straight away.
Is the One Rep Max Calculator free, and is my data stored?
It is free with no sign-up. The calculation runs in your browser, so the values you enter are not sent to or stored on our server.