Calculating Your 1 Rep Max

Have you ever wondered what the maximum amount of weight you can lift for a particular exercise is?

One way to figure that out would be to incrementally try heavier loads until you get to one that you can only lift one time with good form.

While this can certainly be done, for many people it may not be recommended to try to lift a maximal weight load as it can be high risk for injury.

So, what do you do if you still want to know your one rep max but do not want the risk of performing a one rep max lift?

You can use a one repetition max estimation from the calculation below:

Weight(lbs) ÷ (1.0278 – (0.0278 x number of repetitions))

You will need to perform the exercise with a weight that gets you to muscle failure in the 5 to 12 repetition range or so, which is a much safer load to work with. Once you do that you will use the weight that you used, and how many repetitions you did with that weight, and enter it into the equation.

For example, if you squatted 150lbs for 8 repetitions, the calculation would look like this: (Remember your math rules! Brackets first!)

150 ÷ (1.0278 – (0.0278 x 8))

= 150 ÷ (1.0278 – 0.2224)

= 150 ÷ 0.8054

= 186.33lbs

So, your estimated 1RM for the squat in this instance is approximately 186lbs.

If you don’t want to mess around with the math there are also plenty of 1RM calculators you can find online where you just enter your resistance and reps and it will calculate it for you.

Why Calculate a 1RM?

It is a common practice for athletes and weight lifters to lift loads based off a percentage of their 1RM. A rep range of 8-12 repetitions corresponds to about 60-80% of your 1RM. Calculating it this way ensures that you are lifting a weight that is challenging for you, which is what is needed to become stronger.

It is also a great way to track your progress and see your 1 repetition max weight increase over time as you get stronger!