A calorie is a measure of energy that food provides. To lose weight you must burn more calories than you consume. Accurately calculating how many calories you need will help you know how many to cut from your diet to lose weight. No matter which diet you choose, as long as the calories taken in are less than the calories expended you will lose weight. This article uses the Mifflin and St. Jeor formula, which was found by the American Dietetic Association to be the most accurate, to determine someone's basal metabolic rate (BMR), which is the number of calories burned while at rest.
Things You'll Need
Step on the scale to get your weight.
Convert your weight to kilograms, using an online converter (see Resources).
Multiply your weight, in kilograms, by ten.
Convert your height, in inches, to centimeters, using an online converter (see Resources).
Multiply your height in centimeters by 6.25.
Add the sum of Step 3 to the sum of Step 5.
Multiply your age in years by 5.
Subtract this number from the sum in Step 6.
Subtract 161 from the remainder in Step 8 and you have your daily caloric needs. This is the number of calories your body burns during a normal day.
Example of 150 Pound Woman
Use as an example a 5-foot-5-inch tall, 25-year-old woman who weighs 150 pounds. Multiply her weight, in kilograms, by 10:
68.03 x 10 = 680.3
Multiply her height, in centimeters, by 6.25:
165.1 x 6.25 = 1,031.875
Add the result in Step 1 to the result in Step 2:
680.3 + 1,031.875 = 1,712.175
Multiply her age times 5, then subtract that number from the result in Step 3:
25 x 5 = 125
1,712.175 - 125 = 1,587.175
Subtract an additional 161 from the sum in Step 4 to get her basic daily calorie need:
1,587.175 - 161 = 1,426.175 calories