1 Rep Max Calculator

When it comes to flexible dieting, and IIFYM, most people find that exercising is the best way to crank up energy expenditure and build muscle.
If you find yourself in the gym as a bodybuilder or power lifter, strength is going to be a major concern. Following a progressive program such as a linear periodization or a daily undulating periodization program will insure the fastest strength and mass gains possible.

Though not diet based, these weight training or resistance training programs are always based off of your 1 rep max. If you are uncertain of your 1 rep max you can use the 1 rep max calculator below to help get you pretty close to that number.
In many cases we find that the 1 rep max calculator is accurate within 5%. The closer you can get to completing 1 rep at maximum effort, the more accurate it will be, but even if you don’t know your 1 rep max, this calculator will get you pretty close, which will help you with your iifym flexible dieting results!


1 Rep Max Calculator

daily calories required

Weight Lifted


Reps Done

 95% 1 RM
 90% 1 RM
 85% 1 RM
 80% 1 RM
 75% 1 RM
 70% 1 RM
 65% 1 RM
 60% 1 RM
 55% 1 RM
 50% 1 RM
Your One Rep Max: