One-Rep Max Calculator - Free, Instant, In Your Browser
Enter the weight you lifted and how many reps you completed to estimate your theoretical one-rep max.
How to use One Rep Max Calculator
- 1Enter the required date(s) and details above.
- 2Click Calculate - One Rep Max Calculator runs instantly, right in your browser.
- 3Read your result below.
Your file is processed in your browser and is never uploaded.
Frequently Asked Questions
What's the formula?
The Epley formula: 1RM = weight x (1 + reps / 30). It is an estimate, most accurate for rep ranges under about 10.
Is my data sent to a server?
No - everything runs entirely in your browser with JavaScript. Nothing is uploaded.