1 Rep Max

The below article has been adapted from www.bodybuilding.com

We will best explain this by giving a practical example of bent over rows.

Let’s say you know you can lift 45kgs for 10 reps—and only 10 reps, with good form—on the bent-over row. Based on that we can estimate not just your one rep max (100% of your 1RM), but other loads as well: your 85% 1RM , 70% 1RM , or 55% 1RM , depending on what your program calls for. The calculator estimates your one-rep max based on the amount of weight you can lift on a given move, and the number of clean reps you can achieve before muscle failure. Let’s try it for the row, assuming you can do 45kgs for 10 reps. By using the calculation system below it will show an estimated one rep max to be 60kg.


Strength coaches set up programs with percentages based on your 1RM because they don’t know your actual strength level, but they know what percentages they want you to be using relative to your single-rep max. The calculator gives you all the relevant loads, which are done simply by multiplying the percentage by your 1RM (in this case, 60kg). For instance, if you want to do 85% 1RM, the calculator tells you to use approximately 50kg (which is simply 0.85 x 60). Some programs are set up a little differently and will instead tell you to do your 3 rep max, 6 rep max, or some other number. What’s different here is that instead of a giving you a percentage of your one-rep max, you’ll see 3 rep max, which indicates you should use a weight that you can do for three and only three reps. You’ll need the table below to essentially do the conversion in a different way. Let’s say your strength workout calls for you to use your 3RM and 5RM for sets of front squats. Say you know you can do 80kg for a clean set of 8 reps, but you don’t know your one-rep max. If you can just do 8 reps with good form, look at the chart and see that 8 means you’re working at 80% of your 1RM (80% 1RM). Start by computing your 1RM; just divide 80kg by 0.80, which estimates your single-rep max to be 100kg. To find your 3RM, note that 3 corresponds to 93% 1RM, so multiply 100 x 0.93, which estimates your working weight to be 95kg (rounded up). Your 5RM would be 100 x 0.87, giving you a working weight of 87kg. The same program that asked you to do your 3RM and 5RM could alternately have said to do 93% 1RM and 87% 1RM, respectively. Those working weights are exactly the same as you can see in the chart below.



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

Remember that each exercise has its own 1 rep max. Don’t use your back-squat 1 rep max to compute your front squat, or your underhand-grip bent-over row to determine the reverse-grip version—or any other movement. And keep in mind that these are only estimates. The lower your rep count, the more accurate your 1 rep max estimate will be. Providing the weight you can do for 3 reps will give you a more accurate number than if you only know what you can do for 10.

Good luck and CRUSHit.

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