1RM (or One-Repetition Maximum) is a number equivalent to maximum amount of weight that you can lift in a single repetition for a given exercise.

If you can lift, say, 50kg in biceps curl once but not twice, this is your 1RM for biceps curl.

It is often not practical to check your 1RM for every exercise. Using our 1RM calculator, it’s enough to know the number of repetitions you can do with certain weight.

Let’s say you can make 7 repetitions with 42kg in biceps curl. You simply fill 42 for the weight and 7 for number of reps.

The calculator gives you your 1RM for this exercise and also your 40% 1RM, 45% 1RM, 50% 1RM, 55% 1RM, 60% 1RM, 65% 1RM, 70% 1RM, 75% 1RM, 80% 1RM, 85% 1RM, 90% 1RM and 95% 1RM.

So next time you read: “start with 65% 1RM for biceps curl” you will be able to get the number easily.

Please notice that there are several methods of calculating 1RM. Our calculator employs 7 different algorithms and returns the average of the 7 results.