Weight Loss Tools

The Basal Metabolic Rate (BMR), also known as Resting Metabolic Rate, calculator measures the number of calories your body would burn if you sat still all day and didn’t eat anything.

Once you know how fast or slow your body converts fuel into energy, you can use that information to determine the number of calories you need to consume to lose, gain, or maintain your weight based on your daily activity levels. Don’t worry if your metabolism needs a boost. Cardiovascular exercise can increase your BMR, improve your fitness, and make your body a more efficient calorie burner.

How it works: The formula used to calculate your BMR takes into account your weight, height, age, and gender. The Harris-Benedict equation is the most widely used formula for BMR, though a 2003 study published in the Journal of the American Dietetic Association stated that a newer formula, the Mifflin equation, was 10% more accurate than the Harris-Benedict equation.

To calculate your BMR using the Mifflin formula, follow these equations:

Men: (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5
Women: (10 x weight in kg) + (6.25 x height in cm) - (5 x age) – 161

Lazy? Use this online calculator. Or try a more simple formula for quickly determining how many calories to eat on any given day to maintain your current weight: On days when you’re taking it easy and not exercising, multiply your weight (in pounds) by 15 and subtract 500 from that number. And on days that you're active, use the same calculation, but multiply your weight by 18.

How it can help you manage your weight: The number you get from the equation gives you the total number of calories you need to eat to maintain your current weight. To lose weight, shave off 500 calories daily to lose 1 pound per week, or 300 calories daily to lose 2 pounds in a month. “Modifying calories according to activity levels is a good health habit. It [helps people realize] that on low-activity days, fewer calories are needed to maintain weight,” says Burron. “It emphasizes the calories in/calories out formula.”

How accurate is it? According to the Journal of the American Dietetic Association, the Mifflin test used in many BMR formulas provided accurate estimates of actual resting metabolic rates in nonobese and obese individuals. However, Burron says to take these equations with a grain of salt. “It’s hard to predict activity levels, and if you’re planning your caloric needs for the day and things go awry, you may be eating too much or too little,” she says.