Fitness tool
One-Rep Max Calculator
Estimate your one-rep max from the weight and repetitions of a set with the Epley, Brzycki and Lombardi formulas, plus a percentage table for training. Free.
Nothing you enter leaves your device.
Inputs
Results
Enter values to see your results.
Simple steps
How it works
- 01
Choose kg or lb and enter the weight you lifted.
- 02
Enter how many repetitions you completed, from 1 to 10.
- 03
Select Calculate to see your estimated one-rep max and training loads.
Good to know
Frequently asked questions
What is a one-rep max?
The heaviest weight you can lift once with good form. Training plans often use percentages of it.
Why estimate instead of testing?
Testing a true maximum is tiring and riskier. An estimate from a set of a few repetitions is safer and close enough for most training.
Which formula is most accurate?
Each fits some people and lifts better than others. The calculator shows Epley, Brzycki and Lombardi and uses their average.
Why only up to 10 repetitions?
The formulas become much less accurate with longer sets.
What is the percentage table?
It shows loads at percentages of your estimated maximum and the repetitions usually possible at each one.
Is anything I enter stored or sent?
No. The calculation runs in your browser. Nothing you type is saved or sent to a server.
How it is calculated
Epley (1985): weight × (1 + repetitions ÷ 30). Brzycki (1993): weight × 36 ÷ (37 − repetitions). Lombardi: weight × repetitions^0.10. The estimate is the average of the three; the percentage table follows the NSCA.
Sources
- Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. JOPERD 1993;64:88–90
- Epley B. Poundage chart. Boyd Epley Workout, 1985
- National Strength and Conditioning Association. Essentials of Strength Training and Conditioning (percent of 1RM table)
Last reviewed: October 14, 2026