One Rep Max (1RM) Calculator

Pounds ⇔ Kilogram

Other helpful calculators in Fitness category.

Have you ever wondered how many pounds you can lift in one workout? Loading weights is one way to find out, but it's not a very safe way, and it can also mess up our training schedule.

On the other hand, if you enter our calculator above with which weight and how many repetitions you do in an exercise; we can tell you your 1 rep max i.e. 1RM!

Thus, you can safely follow your progress and design your training program in a more scientific way!

What is 1RM?

1RM or 1TM is the maximum weight you can lift in 1 rep.

Why is this important? Because our 1RM value is an "intensity" unit that shows how strong we are in the relevant exercise.

For example, you can do 10 repetitions with 100 kg in the Squat exercise. This shows that you have about 135 kg of 1RM power.

After a few weeks, when you do 6 reps with 120 kg, your 1 rep max will be approximately 144 kg.

1RM calculation gives you the opportunity to track your performance without breaking your training program and without putting yourself at risk!

Of course we have to stay away from some exhaustion to get a good workout. The point of exhaustion is frustrating, and if we are constantly exhausted it will be difficult for us to make progress. For this reason, we must manage the density and “leave some force in the tank!”

Training intensity can be managed with percentages or RPE over 1TM. The method we recommend is to keep the RPE scale in mind and keep our sets generally in the RPE 7-9 range.

In other words, as you can read from the table below, if 100 kg and 10 repetitions are our maximum strength, it will be more efficient to do 10 repetitions with weights such as 90-95 kg in our sets.

Remember: trying maximum and improving maximum performance are two different things!

To learn more about RPE and best manage training intensity, we recommend watching the video below!

1 Repetition Maximum Calculation Formula

There are many formulas for calculating 1RM, of which we use the Wattan formula.

This resource checked many calculation formulas and found the Wathan formula the most consistent.

In our personal tests with different calculators, and when we tested the data of the people we trained, the most successful result we encountered was again with the same 1RM calculation formula.

Therefore, you can manage your training program by relying on this formula.

Lesuer, DA, Mccormick, JH, Mayhew, JL et al. (1997). “The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift”. J Strength Cond Res 11: 211–213