One-rep max calculator
Estimate one-rep max from weight and repetitions.
One-rep max calculator
Fill in the fields and the result will appear here automatically.
Use this 1RM calculator to estimate your one-rep max and training percentages.
How it works
Formula and logic
The calculator uses a common 1RM estimate formula for sets up to moderate repetitions.
Example
Enter 80 kg for 5 reps to estimate your approximate one-rep max.
Fields and units
- Weight — unitless
- Repetitions — unitless
How to use
- — Enter working weight.
- — Enter repetitions.
- — Review estimated 1RM and percentages.
Enter working weight. Enter repetitions. Review estimated 1RM and percentages.
Sources and review status
- Calculation method
- The calculator uses a common 1RM estimate formula for sets up to moderate repetitions.
- Data or methodology source
- The formula and input definitions documented on this page.
- Last reviewed
- Limitation
- The result is guidance and does not replace an individual medical or training assessment.
FAQ
How accurate is this one-rep max calculator?
The result is a practical estimate based on the values you enter and the formula shown on the page.
Does this one-rep max calculator require an account?
No. The calculator works in your browser and does not require registration.
Can I share a one-rep max calculator result?
Yes. Use the share link to copy the current inputs in the page URL.