One-Rep Max Calculator
Estimate one-repetition maximum from a submaximal set using Epley and Brzycki equations and compare percentage-based training loads.
Estimate one-rep max (1RM)
Enter a weight and completed repetitions to compare two common 1RM prediction equations.
| % of midpoint 1RM | Estimated load |
|---|
1RM prediction formulas used
The calculator compares two widely used equations. Epley: 1RM = weight × (1 + reps/30). Brzycki: 1RM = weight ÷ (1.0278 − 0.0278 × reps). Published research continues to compare these and other repetition-to-failure equations, and no single equation is perfect for every exercise or population.
Why the tool shows two estimates
Showing both equations makes the uncertainty visible. The midpoint is provided only as a convenient planning reference for the percentage-load table; it should not be treated as a measured maximum.
Best repetition range for estimation
Prediction generally becomes less dependable as repetitions climb. Sets near the lower repetition range are usually more useful for estimating maximal strength than very high-repetition endurance sets.
Use a predicted 1RM conservatively
Do not attempt an unsafe maximal lift merely to validate a calculator. Technique, equipment, fatigue, exercise selection and training experience all affect the relationship between a submaximal set and true 1RM.
Use submaximal estimates safely
One-rep-max equations are most useful when the test set is performed with sound technique and a moderate repetition count. Accuracy generally worsens as repetitions become very high or fatigue changes movement quality. Different exercises and athletes can also fit different equations. Use the result to plan approximate training percentages, then adjust loads based on actual performance, bar speed, repetitions in reserve and coaching guidance rather than forcing a predicted maximum.