One Rep Max Calculator
Enter a weight and how many reps you completed to estimate your one-rep max (1RM), using the Epley formula.
| % of 1RM | Weight | Typical reps |
|---|
About the One Rep Max Calculator
The One Rep Max Calculator estimates the heaviest weight you could lift once from a lighter weight and the number of repetitions you completed. It also shows a table of training percentages with typical repetition counts.
A one-rep max (1RM) estimate uses a formula that assumes a pattern between weight and reps. This tool uses the Epley formula, 1RM = weight × (1 + reps / 30). They are most accurate for sets of about 2 to 10 reps, and less so for high reps. The percentage table helps you plan training loads, for example around 80 percent of 1RM for roughly eight repetitions.
How to use it
- Enter the weight lifted.
- Enter the repetitions completed with good form.
- Read the estimated 1RM.
- Use the table to plan your sets.
Tips and good to know
- Warm up properly and use a spotter for heavy lifts.
- Estimates are less reliable above 10 reps.
- Test a true max only if experienced.
Frequently asked questions
Is it exact?
No, it is an estimate.
Which formula is used?
The Epley formula, 1RM = weight × (1 + reps ÷ 30).
How often should I test my max?
Many lifters re-estimate every few weeks.