One Rep Max Calculator

What is a One Rep Max (1RM)?

A one rep max, abbreviated as 1RM, refers to the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. This is typically used in strength training and weightlifting to measure an individual's maximum strength for specific exercises like the squat, bench press, or deadlift.

The 1RM is important for several reasons:

1. Measuring strength: It provides a clear benchmark of your current strength level.
2. Program design: Many training programs base their prescribed weights on percentages of your 1RM.
3. Progress tracking: Periodically testing your 1RM allows you to track strength gains over time.
4. Competition: In powerlifting and Olympic weightlifting, competition results are based on 1RM lifts.

Testing your true 1RM can be physically demanding and potentially risky, especially for beginners as you start with a light weight and then gradually increase the weight and perform single repetitions with adequate rest in between.

The alternative is to use such a One Rep Max Calculator. Instead of testing out the max weight directly, we will use a submaximal weight and the reps you can perform with it to estimate your 1RM.

There are many different formulas to calculate the 1RM but the most common one (and the one this calculator also uses) is:

1RM = w × (1 + r / 30) 

where w is the weight and r is the number of reps you can perform with that weight.