In order to obtain maximum muscle strength, special equipment and multiple tests must be used, but quick calculation of strength is very important and vital for trainers. For this reason, we have implemented here for quick access using common online calculator formulas to determine maximum power, also known as one repetition maximum. In order to be able to determine the maximum strength in a muscle, it is enough to put the amount of weight and the number of repetitions until exhaustion in the online calculator so that the calculation can be done quickly.