Estimate Calorie Needs

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Estimate Calorie Needs

The Harris-Benedict equation is often used to estimate your calorie needs. This method takes into account height, weight, gender and activity level. It is not complicated, but merely a matter of measuring your height and weight and using those values in the equations shown below.

Keep in mind that people are unique and their physiology will vary.

This is just a way to estimate calorie needs. However, it provides a good beginning for understanding how much food your body requires each day. (The next step is education yourself about the energy value (calories) in the foods you include in your diet each day.)

Quick tip: One gram of fat has more than twice as many  calories as the same amount of carbohydrates and protein.  You need healthy fats in your diet, but be aware of excess fat in your diet if you are trying to lose weight. Make your fat calories count!

Here is the Harris-Benedict equation for men and women:

Men (metric) 

BMR = 66.5 + (13.75 x weight in kg) + (5.003 x height in cm) – (6.755 x age in years)

Women (metric) 

BMR = 655.1 + (9.563 x weight in kg) + (1.850 x height in cm) – (4.676 x age in years)

Men (imperial) 

BMR = 66 + (6.2 x weight in pounds ) + (12.7 x height in inches ) – (6.76 x age in years)

Women (imperial) 

BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)

In order to estimate calorie needs, you need to plug in your age, height, and weight. The number you get is the total number of calories you need each day merely to exist (also known as your basal metabolic rate, BMR). For example, a 58-year-woman who is 5' 8" and weighs 150 pounds has a basal metabolic rate of 1355 calories.

Since you do not sit still all day, you’ll burn more calories than your BMR. To get an estimate of how many calories you burn each day, you can use the “activity factors” listed below.

-Sedentary: Minimum of movement, much time spent TV watching, reading, etc. Activity factor = 1.4

-Light activity: Office work, about1 hour of moderate exercise/activity during the day. Activity factor = 1.5

-Moderate activity: Light physical/manual labor during the day, plus more active lifestyle. Activity factor = 1.6

-Very Active: Active military, full time athlete, hard physical/manual labor job. Activity factor = 1.9

Choose the factor that fits your lifestyle and multiply it by your BMR. Be sure to accurately assess your activity level. If in doubt, especially if you want to lose weight, use the lower factor rather than risk overstating when you estimate calorie needs.

For the example we cited above, if we choose the most common activity factor of 1.5 and multiply that by 1355 calories, we get 2033 calories. This number is the total calorie needs, or approximately the amount of calories that person should eat each day to maintain her weight. To lose weight, she would need to eat less than this. To gain weight, she would need to eat more.

After you use this formula to estimate your calorie needs, you can then create an eating plan to gain, lose or maintain your weight.

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