Find the number of reps that you can perform with a weight to concentric failure. For example, if you can do eight repetitions of an exercise with a specific amount of weight and could not possibly do another repetition (rep), that is your point of failure. Find the percentage associated with that number of repetitions from the table above.
Now, divide the weight that you can do by that percentage using decimals (83 percent equals .83) and that will give you an approximation of your one repetition maximum. For example, if you can perform 10 reps with 175 lbs. in the bench press, that means that 175 lbs. is 75% (0.75) of your one repetition maximum. So you would take 175 divided by .75 and that would equal 233 lbs. Now let’s go lift some weight!