Free, runs entirely in your browser — no sign-up, no file upload to a server.
What does One-Rep Max Calculator do?
It estimates your one-rep max (1RM) for any lift from a weight and rep count you've actually performed, plus training percentages for programming.
How accurate is the result?
It uses a standard, widely used estimation formula, but your true one-rep max can vary based on form, fatigue, and the specific lift — treat it as a planning estimate, not an exact measurement.
Is my data sent anywhere?
Everything runs in your browser — nothing you type or paste is sent to a server.
How do I report a problem or request a feature for this tool?
Use the Contact / Feedback page — select "One-Rep Max Calculator" as the related tool so we know exactly which tool you mean, then describe the bug or the feature you'd like to see.