About Us

The 1RM Calculator is a completely free online tool that helps gym-goers and weightlifters estimate the maximum weight they can lift for any given exercise. You simply need to enter the weight lifted and the number of repetitions performed, and the calculator provides an estimate of your strength, a percentage table, and a calculation of the plates required for training—all instantly.

Why did I create this website?

During gym sessions and strength training, I often noticed people attempting to lift excessively heavy weights to test their true strength, which frequently carries a risk of injury or severe joint pain. I wanted to create a quick and easy tool that would allow any gym enthusiast to estimate their maximum potential—using lighter weights and more reps—without the risk of injury, and to design their workout plans more effectively.

How are the figures calculated?

This calculator utilizes seven well-known and validated formulas from the science and fitness industries:

Epley

Brzycki

Lander

Lombardi

Mayhew

O’Conner

Wathan

By default it shows the Epley result, one of the most widely used formulas. You can switch to any other formula, or to the average of all seven. Every formula gives an estimate, not an exact figure. Your real max depends on sleep, fatigue, technique and the lift itself, and estimates are most reliable with sets of 10 reps or fewer.

Questions or suggestions?

If you have any questions, spot an error, or wish to offer a suggestion, please feel free to contact us via our ‘Contact Us‘ page.

This site is for general fitness information and is not medical advice. Please read our Disclaimer.