BMR Calculator

What is BMR? Your basal metabolic rate, or BMR, tells you how many calories your body burns just to keep its organs going. If you stayed in bed all day and did nothing, it is how many calories your body needs to keep functioning.

Blood flow, respiration, maintaining body temperature, keeping your organs working, making new cells, hormones, and other processes require energy, and a BMR calculator can tell you how many calories your body burns in a day to keep your body alive.


Just about 10 percent of the calories your body burns in a sedentary state is for mechanical functions, like heartbeat, breathing, and digestion. The other 90 percent is spent maintaining fluid levels in your tissues by osmoregulation. Your basal metabolic rate does not include any calories you burn through exercise or daily living activities.

Calculate BMR for Age

As you get older, your BMR decreases. Once you hit 20, it decreases by about 2 percent every ten years. You start to gain weight as you get older in many cases because your BMR is lower than it was, even though you are as active as you used to be. Your BMR is the most important determinant of your general metabolic rate and how many calories your body needs to maintain, lose, or gain weight.

Men and Women Differences

There are differences between men and women when it comes to BMR. Women tend to have a lower BMR than men naturally because men typically have a lower percentage of body fat. They have more muscle in most cases, which means that they need a higher rate of metabolism to keep that muscle tone.

How to Calculate BMR

To calculate BMR, you need to know how much you weigh, your height, and your age. Other factors play a role in your BMR as well, such as your gender and individual genetic factors. Knowing your BMR can help you identify and reach your fitness goals.

An equation called the Harris-Benedict equation has been used for years and is still used to figure the BMR. You can use the BMR formula, or you can use our free BMR calculator to avoid having to do any calculations yourself.