The number of calories your body burns each day simply existing depends on myriad factors including body fat, muscle mass, gender, age, hormones and overall health. This number can be calculated and is called basal metabolic rate, or BMR. Your BMR is based on your personal basal metabolism, or the number of chemical activities that take place in your body to keep you alive.

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## How It Adds Up

To figure out how many calories you need to exist, you need to calculate your BMR. You will need to know your height in centimeters and your weight in kilograms. To find your height in centimeters, multiply your height in inches by 2.54. To find your weight in kilograms, multiply your weight in pounds by 0.45. For the equation, men begin with the number 5 and women begin with minus 161. Then, multiply your age by 5 and subtract that number from your starting number. This is called variable C. Next, multiply your weight in kilograms by 10 and multiply your height in centimeters by 6.25. Add these two numbers together to get variable F. Variable G is the value assigned to your usual activity level. For sedentary activity, which would be the amount of activity necessary to simply exist, use the number 1. Finally, multiply variable F by variable G and add the product to variable C. This final number is the number of calories you burn each day by just existing.