1-Rep Max Calculator

Learn more about the Epley Formula

The Epley Formula is a widely recognised method for estimating the one-repetition maximum (1RM) in weightlifting. Developed by Boyd Epley, the National Strength and Conditioning Association (NSCA) founder, this formula is simple, quick, and commonly used because of its practicality and relative accuracy.

Formula

The Epley Formula is expressed as:

1RM = Weight × (1 + Reps / 30)

Where:

• 1RM is the one-repetition maximum.
• Weight is the weight lifted.
• Reps is the number of repetitions performed.

Usage and Application

• Estimating Maximal Strength: The formula estimates the maximum weight a person can lift in a single repetition for an exercise. This is particularly useful when testing an actual 1RM might be risky or impractical.
• Programming and Progress: Athletes and coaches use the estimated 1RM to plan and adjust training programs. It helps in setting appropriate weight levels for various strength training exercises.
• Safety: Since testing a true 1RM can be physically demanding and potentially risky, the Epley Formula provides a safer alternative to gauge a person's strength.

Accuracy and Limitations

• General Accuracy: The Epley Formula is generally considered accurate for a moderate number of reps (up to 10). The accuracy may diminish with a higher number of repetitions.
• Exercise Specificity: The formula tends to be more accurate for specific exercises (like the bench press) than others. It is always recommended to use exercise-specific formulas for greater accuracy.
• Individual Differences: Factors such as muscle fibre composition, training experience, and fatigue levels can affect the formula's accuracy. It is a general estimation and may not be equally accurate for all individuals.