RM Calculator uses the seven best formulas for calculating your max reps (Lombardi, Brzycki, Epley, Mayhew, O'Conner, Wathan, Lander), you can choose one of them, or find an average for the most accurate result of possible max reps.
Knowing how many repetitions you should be doing and could be doing is important to determine how strong a person is at a certain time and is useful for competing in certain sports such as weightlifting or powerlifting, planning routines, both strength and hypertrophy, and more!
1RM (One Repetition Maximum) in weight training, is the maximum amount of force that can be generated in a maximal contraction. One repetition maximum can be used to determine the maximum strength of a person and is the method to determine the winner in sports events like powerlifting.
1RM also be used to determine the desired load for an exercise (as a percentage of 1RM).
The repetition maximum (RM) can be calculated directly by testing highs, or indirectly using submaximal estimate. It is preferable to use submaximal estimate because it is safer, faster and less confusing for inexperienced athletes.