One-rep max calculator
HealthEstimate your one-rep max from a submaximal set using Epley and Brzycki formulas.
Your results
Estimate your one-rep max from weight and reps.
How 1RM is estimated
Epley multiplies the weight by (1 + reps/30) and Brzycki multiplies by 36/(37 - reps). We average both formulas to reduce the error of any single method.
How accurate is the estimate?
Both formulas are most accurate between 1 and 10 reps. Beyond that, the estimate drifts more. Use the result as a starting point and adjust based on how the lift actually feels.
Frequently asked questions
Answers to the most common questions about this tool.
How is this result calculated?
It uses the method and inputs described on this page to provide an informational estimate.
How accurate is the result?
It is an estimate and should be interpreted as a guide, not an exact measurement.
When should I seek professional advice?
Seek qualified advice for symptoms, pregnancy, illness, medication use, or clinical decisions.
What information do I need to enter?
Enter current, accurate details and select the correct units before calculating.
What can affect this estimate?
Individual factors such as health, activity, body composition, and measurement technique can affect it.
Sources and methodology
Methodology: 1RM estimate
Calculates Epley and Brzycki equations and also shows their average, which is a ToolsRL presentation choice.
The average is not an independently validated equation.
Last reviewed
July 15, 2026