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Calculate Your One-Rep Max (1RM)

Learn how to compute your one-rep max (1RM) using these calculation methods.

Do you want to find out how strong you are? Sure; we all do. Need to know what your one-rep max (1RM) is for a new workout program based on percentages? It's simple! Use the following calculator and formulas to figure it out. Of course, this is only an estimate. Your actual one-rep max could be slightly higher or lower (hopefully higher!)

This method is based on a formula from "Maximum based on reps" by J. Landers, published in 1985 in an NSCA journal. Just do a set to failure on any exercise, then enter in how much weight you did and how many reps you finished (without help) into the form below.

One-Rep Max (one-rm) Calculator

Weight Lifted Reps

Your One-Rep Max (one-rm): ?

95% one-rm 70% one-rm
90% one-rm 65% one-rm
85% one-rm 60% one-rm
80% one-rm 55% one-rm
75% one-rm 50% one-rm

Enter the amount of weight you lifted and the number of reps you lifted it for (the number of reps must be between 1 and 10 in order for the calculation to work).

Your One-Rep Max will appear at the top and all of your percentages will appear below it.

1 Rep Max Percentages

1 100
2 95
3 93
4 90
5 87
6 85
7 83
8 80
9 77
10 75
11 73
12 70


Find the number of reps to concentric failure that you can perform with a certain weight. In other words, if you can only do eight reps with a certain weight and could not possibly do another full rep, that is your point of failure. Find the percentage associated with that number of repetitions from the table above.

Now, divide the weight you can do by that percentage using decimals (for example, 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. You should probably use your calculator, we knew a guy who did it in his head and said he could bench 3,000 lbs... Good luck!


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Calculating Your 1RM
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