Calculate Your 1 Repetition Max

Calculate your 1 Repetition Max (1RM):

Your 1 Repetition Max or 1RM is the max amount of weight you can lift in a certain exercise for 1 repetition. This helps you determine what percentage of that to use to achieve your training goals.

Usually, getting up to that max amount of weight can be dangerous or you might need a spotter that’s not always with you. What you can do is work up to the max amount of weight you can lift while feeling safe, for a certain amount of reps. The closer you are to 1 rep the better. Then you can use the formula below to convert to your 1RM.

For example, I start a bench press with 10 repetitions and 1 set comfortably. I will then increase to a weight that I can do for 8 repetitions and 1 set, then one that I can do for 6 repetitions and 1 set. Here is where it tends to get more challenging, so you could do a test for the max amount of weight you can lift for 5 repetitions and plug in the formula below.

Now, when you are testing for 5 repetitions, you have to make sure that you can lift that weight for only 5 repetitions and nothing more. If you are able to get the 6th repetition, take a 3-5 minute break increase the weight by about 5 lbs. and try again. If once again you are able to do a 6th rep, repeat the process until you can only do 5 repetitions, then plug in the formula.

Brzycki formula: 

1RM = W x (36 / (37 – R))            W= Weight, R= Repetitions

How to use your 1RM for training purposes:

15+ repetitions at 55% - 65%

12 – 15 repetitions at 65% - 75%

8 – 12 repetitions at 75% - 85%

6 or < repetitions at 85% – 95%

To work on muscle endurance, it is recommended to work in the 12 to 15+ repetitions range, meaning 55%-75%% of your 1RM.

For muscle hypertrophy (muscle growth), aim for the 8 – 12 repetition range or 75%-85% of your 1RM.

Finally, if you are aiming to increase muscle strength, you are going to target the 6 or fewer repetitions at 85%-95% of your 1RM

There are a couple of things to note. Beginner athletes are going to probably experience some muscle hypertrophy and increase in strength no matter what intensity they choose to go with. After a few weeks of training, this won’t be the case, due to the adaptation of the body to the training stress.

Furthermore, it is recommended that an inexperienced athlete get the help of a coach when working in the 85%-95% zone. Training at this intensity especially could lead to injury if proper form is not maintained throughout the training session.