Health & Fitness
One Rep Max Calculator - 1RM
Estimate your one rep max and training max from a working set.
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
Which formula is used?
This calculator uses the Epley formula for estimating 1RM.
How many reps should I use?
Best results are usually with 3-10 reps.
What is training max?
Training max is 90% of estimated 1RM, often used for programming.
Related tools
About this tool
Inputs
- Weight lifted
- Reps
Results
- Estimated 1RM
- Training max (90%)
Figuring out estimate your one rep max and training max from a working set no longer requires manual arithmetic. The One Rep Max Calculator walks you through the math step by step. Type in weight lifted and reps. The computation runs immediately, giving you estimated 1rm and training max (90%). Body composition, metabolism, and vital signs interact in complex ways that a single number cannot capture.
From students to professionals, anyone who needs to estimate your one rep max and training max from a working set benefits from getting an instant, verifiable answer. Training max is 90% of estimated 1RM, often used for programming. Measure consistently — same time of day, same conditions — for the most reliable comparisons. Try adjusting one input at a time to see how it affects the outcome — this is the fastest way to build intuition about the relationship between the variables. Basal metabolic rate estimates use equations like Harris-Benedict or Mifflin-St Jeor, which factor in age, sex, height, and weight. Individual variation means two people with identical numbers can have very different health profiles.