One-rep max calculator
Enter the weight you lifted and how many reps you did to estimate your one-rep max and see working weights for your training.
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What your result means
Your one-rep max (1RM) is the heaviest weight you could lift for one clean repetition. Testing it directly is tiring and carries more risk, so this calculator estimates it from a lighter set.
Two common formulas are shown, Epley and Brzycki. They usually land close together. The estimates are most reliable for sets of 10 reps or fewer and become less reliable as reps go up.
The table shows weights at 50% to 100% of the average of the two estimates. Lower percentages are used for higher-rep work and warm-ups, and higher percentages for heavy sets. Loads are rounded to the nearest 0.5.
How it's calculated
Formula
- Epley: 1RM = weight × (1 + reps ÷ 30)
- Brzycki: 1RM = weight × 36 ÷ (37 − reps)
- Table: working weight = average of the two estimates × percentage, rounded to the nearest 0.5
- Reps must be a whole number from 1 to 12. For one rep, the estimate is the weight you lifted
Brzycki cannot be used at 37 or more reps, and both formulas drift further from real results as reps increase, so the calculator limits reps to 12.
The result is in the same unit you entered, kilograms or pounds.
Sources
- Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. JOPERD, 1993
- Epley B. Poundage chart. Boyd Epley Workout, University of Nebraska, 1985
Learn more in the Academy
Frequently asked questions
Neither is better in every case. They agree closely at low reps. Use the average, or whichever result matches how your own lifts have gone before.
Estimates get less reliable as reps rise, and one of the formulas stops working at 37 reps. A set of 12 or fewer gives a more useful estimate.
Pick a percentage that matches your goal and the number of reps in your program, then lift the weight shown. Many programs list their sets as a percentage of your one-rep max.
A heavy single carries more risk than lighter sets. If you try one, warm up well and use a spotter or safety bars. An estimate from a lighter set avoids this.
Calculators give estimates for healthy adults and are not medical advice. Talk to a qualified professional before changing your training or nutrition, especially if you have a health condition.
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