One Rep Max Calculator
Estimate your maximum lift and generate percentage-based training loads from submaximal performance.
1RM Estimates
Percentage Table
| % of 1RM | Weight | Typical Use |
|---|
What is One Rep Max Calculator?
A One Rep Max (1RM) Calculator estimates the maximum amount of weight you can lift for a single repetition of a given exercise. Testing your true 1RM can be physically demanding and carries injury risk, so estimation from submaximal sets is a safer and practical alternative for most lifters.
This calculator applies four well-known formulas: Epley, Brzycki, Lombardi, and Mayhew. Each formula behaves slightly differently across rep ranges, so reviewing multiple estimates gives you a more reliable picture of your strength capacity. The included percentage table helps you plan training loads for different goals.
How to Use
- Enter the weight you lifted and the number of reps you completed (between 1 and 30).
- Select your unit system: pounds or kilograms.
- Click Calculate 1RM to see estimates from all four formulas.
- Use the percentage table to choose appropriate training weights for strength, hypertrophy, or endurance.
Frequently Asked Questions
Which 1RM formula is most accurate?
Brzycki is widely used and accurate for moderate rep ranges (1-10). Epley tends to overestimate at higher reps, while Lombardi and Mayhew offer alternative curves. Comparing multiple formulas is recommended.
Can I use this for any exercise?
Yes, but accuracy varies by movement. Compound lifts like squats, bench press, and deadlifts tend to produce more consistent estimates than isolation exercises.
Is testing 1RM necessary?
No. Submaximal estimation is safer and sufficient for program design. True 1RM testing should be reserved for experienced lifters with spotters.
What rep range is best for estimation?
Estimates are most accurate when based on sets of 1-10 reps. Above 10 reps, fatigue and muscular endurance play larger roles, reducing prediction accuracy.