Estimate your one-repetition maximum from a submaximal set using Epley, Brzycki and Lombardi formulas.
Estimate your one rep max
Training loads from the average estimate
These are mathematical estimates, not a guarantee that the displayed maximum or training loads can be lifted safely.
One rep max formulas
Brzycki: 1RM = weight × 36 ÷ (37 − reps)
Lombardi: 1RM = weight × reps0.10
Different equations produce slightly different estimates because they model fatigue differently. This calculator displays all three and uses their mean as the headline value. When one repetition is entered, the lifted weight itself is treated as the 1RM.
How to use the calculator
- Use a recent technically sound set completed with consistent range of motion.
- Enter the weight and the number of clean repetitions.
- Select kilograms or pounds.
- Calculate to compare formulas and view percentage-based training loads.
Worked example
If you lift 80kg for 6 clean repetitions, the Epley formula estimates 96kg, Brzycki estimates about 92.9kg and Lombardi estimates about 95.7kg. Their average is approximately 94.9kg.
| Formula | 80kg × 6 reps |
|---|---|
| Epley | 96.0kg |
| Brzycki | 92.9kg |
| Lombardi | 95.7kg |
| Average | 94.9kg |
Choosing a useful rep range
Estimates are generally more useful from lower-repetition sets performed close to the lifter’s true capacity with consistent technique. High-repetition sets introduce more variation from fatigue, pacing and muscular endurance. The calculator limits entries to 12 repetitions for that reason.
Use estimated loads safely
An estimated 1RM can help programme training without attempting an all-out maximum. Use suitable warm-ups, equipment and supervision for heavy lifting, and stop if technique breaks down or pain occurs. The National Strength and Conditioning Association provides a reference training-load chart for estimated 1RM values.
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Frequently asked questions
What does one rep max mean?
It is the greatest load a person can lift once through the required range of motion for a particular exercise.
Which 1RM formula is most accurate?
No single formula is best for every lifter and exercise. Comparing several estimates helps show the likely range.
Can beginners use this calculator?
Yes, but beginners should prioritise technique and avoid maximal attempts without suitable instruction and supervision.
Can I use pounds instead of kilograms?
Yes. The equations work with either unit as long as the same unit is used throughout.
Why are repetitions limited to 12?
Prediction uncertainty usually grows with higher-repetition sets because endurance and pacing influence the result more strongly.