One Rep Max Calculator

A “one rep max” (one-repetition maximum) is the maximum weight a person can lift for one complete repetition of a specific exercise while maintaining proper form. It is a measure that is commonly used in weightlifting competitions since it represents the peak force that a person’s muscles can generate in an all-out effort.

A person’s one rep max typically differs based on the exercise, whether it be a bench press, squat, deadlift, overhead press, or whatever other exercise is being performed. Thus, it is important to measure a one rep max for a given exercise rather than applying a one rep max in one exercise to other exercises.

How to use this calculator to save (and improve) your 1RM

After using the calculator to calculate your 1RM, there will be a save icon on the right side of the result bar. Click the save icon to save your 1RM for future reference. You can then look back at your previous 1RM for various exercises to gauge your progress. The following sections provide detail on the 1RM calculation as well as methods for working toward improving your 1RM.

Why one rep max is important

Knowing your one rep max (1RM) is valuable because it provides a quantitative measure (or estimate) of your maximal strength for a given exercise, which enables you to design a workout program and train accordingly based on your goals.

For example, you can use your 1RM to manage your targeted training intensity. This enables you to design a workout program that is challenging enough to promote strength gain while also ensuring proper technique and safety.

Since it provides a quantitative measure, knowing your 1RM also allows you to track your strength progress over time and set goals for improvement. Without a quantitative measure, it can be difficult to motivate ourselves to train. Seeing improvement in your 1RM can help motivate you to train, or if you don’t see improvement, you can use your 1RM to adjust your workout program to help you achieve your desired strength gains.

How to measure one rep max

The two primary methods for measuring one rep max are direct measurement by performing a strength test for a given exercise and using estimation methods. There are advantages and disadvantages to using either method, as described below.

How to directly measure one rep max

Directly measuring one rep max involves progressively increasing the weight as you perform a specific exercise. As you increase the weight, taking breaks between each trial, the number of repetitions of the exercise you can perform should continue to decrease until your muscles reach failure and you can only perform one repetition of the exercise with proper form.

This method of measuring one rep max can be dangerous, and it is important to only attempt using direct measurement for exercises you are experienced in performing, ideally with the help of a spotter (someone who can help you push your limits while ensuring your safety in the case that anything goes wrong). The steps for directly measuring your one rep max are generally as follows:

• Warm up: Begin by warming up the muscle groups you will be using.
• Find a spotter: Finding your one rep max involves pushing your limits. Having a spotter helps you do this in a safe manner.
• Start with a comfortable weight: The weight you select shouldn’t be too light. It should be a weight you know you can lift for ~5-10 reps, but not a weight that you can lift for many more.
• Rest and recover: Between each set, you should rest and recover fully before attempting the next set. Your break may last anywhere from 2-5 minutes.
• Progressively increase weight: After enough rest, attempt the next weight. Depending how you felt on the first set, you may find yourself wanting to increase the weight significantly if the first set was too easy, or you may find that the first weight you selected was more difficult and closer to your 1RM than expected. In the second case, the next selected increment may be smaller.
• Repeat the process: Continue the process of resting and recovering and progressively increasing weight. Once you can only do one repetition with good form, you have found your estimated one rep max. Note that form is incredibly important. It may be possible to lift more weight if your form is compromised, but this is not a good estimate of your one rep max and can result in injury. Remember that injury will slow your overall progress towards your strength goals, so push your limits as safely as possible.
• Record your estimated 1RM: Note your 1RM and save it somewhere (you can do so in the above calculator).

Generally, it is not recommended for beginners to attempt direct measurement of their one rep max. When a person first starts weightlifting, it is better to focus on learning proper form for a given exercise rather than trying to find their one rep max. However, as discussed above, knowing your one rep max can help a person design a challenging and effective workout program, even as a beginner. Thus, it can still be valuable for beginners to determine their one rep max. One way to do this more safely than using direct measurement is to use estimation methods for finding your one rep max.