Calculate Your One-Rep Max (1RM)
Use the calculator below for any lift to estimate your one-rep max based on the amount of weight you can lift on a given move, and the number of clean reps you can achieve before muscle failure.
Why do you need to calculate your 1RM?
Strength coaches set up programs with percentages based on your 1RM because they don’t know your actual strength level, but they know what percentages they want you to be using relative to your single-rep max. The calculator gives you all the relevant loads, which are done simply by multiplying the percentage by your 1RM.
Your one-rep max (1RM) is the maximum weight you can lift in any given exercise. While you can use your 1RM to show off on social media, its uses and benefits reach far beyond that. This number is essential to many strength-training coaches, as many programs are designed with your 1RM as the basis.
How do I calculate my 1RM?
There are generally two ways to calculate your 1RM. The first is a direct method in maximal testing, and the second is using submaximal estimation. Submaximal estimation is what we’re going to tackle today. It’s the safer, more practical, and less intimidating alternative between the two. Using several equations, you can calculate your 1RM as a function of weight and reps. Here are some of the well-known equations made by expert strength coaches.
The first and most widely used is the Brzycki Formula, named after its creator Matt Brzycki.
1RM = (weight x 36)/(37 – reps)
1RM = (0.033 x weight x reps) + weight
1RM = weight + weight (0.033 x reps)
1RM = weight x (reps ^ 0.10)
1RM = (100 x weight)/(101.3 – 2.67123 x reps)
O’ Conner et al. equation
1RM = weight (1 + reps/40)
1RM = (100 x weight)/(48.8 + 53.8e^(-0.075 x reps))
Remember: each workout has its own 1RM, so you can’t use the 1RM of your back squat for your bench press.