One Rep Max Calculator

Discover your true strength potential with our one-rep max (1RM) calculator. Determine the maximum weight you can lift for a single repetition on any exercise. Knowing your 1RM is crucial for effective workout programming and tracking progress.

What is One Rep Max (1RM)?

One Rep Max (1RM) is the maximum amount of weight you can lift for one repetition of a given exercise. It is a common measure of maximal strength and is used to help design training programs.

Why Calculate Your One Rep Max?

Calculating your 1RM helps in understanding your current strength levels and designing effective workout programs. It allows you to set appropriate weights for different rep ranges and track progress over time.

How is One Rep Max Calculated?

The One Rep Max (1RM) is calculated using the Epley formula:

1RM = weight × (1 + reps / 30)

This formula provides an estimate of the maximum weight you can lift for a single repetition based on the weight you can lift for a given number of reps.

Reference: Epley, B. (1985). Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises.

Methodology for Calculating Rep Percentages

Using Epley's equation, we can estimate how many repetitions a person can typically do at a given percentage of 1RM. The formula can be rearranged to solve for the percentage of 1RM for a given number of repetitions:

% of 1RM = 100 / (1 + reps / 30)

This calculation provides a theoretical model for the relationship between repetitions and percentage of 1RM. However, it's important to note that these are estimates, and individual performance can vary based on factors such as training experience, specific exercises, and personal physiology.

The percentages shown in the results table are derived from this calculation, offering a guide for how much weight you might be able to lift for different rep ranges based on your estimated 1RM.

What Percentage of One Rep Max Should I Lift?

Depending on your training goals, you should lift different percentages of your 1RM:

Strength: 85-100% of 1RM
Hypertrophy (Muscle Growth): 70-85% of 1RM
Endurance: 50-70% of 1RM

How to Optimize Training with One Rep Max

Using your 1RM, you can optimize your training by adjusting the weights and reps for different exercises. It helps ensure you are lifting enough weight to challenge yourself without risking injury.

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