The BMR Calculator measures your Basal Metabolic Rate (BMR) that represents an estimate of calories burned while resting - also know as resting metabolic rate (RMR). It is measured in kilo joules per hour per kilogram of body mass.
As humans, we burn up energy around the clock regardless of what activity we undergo (that includes sleeping), however the BMR calculation does not take into account any type of additional physical activity other than a restful state of the body. A restful state refers to the energy sufficient only for the functioning of the vital organs: the heart, lungs, nervous system, kidneys, liver, intestine, sex organs, muscles, brain and skin.
If you what to calculate the daily calories intake requirements depending on how much exercise you get, check out the Calorie Intake Calculator for a more accurate estimation of your daily caloric intake needs.
On an average around 50% to 75% of the daily energy expenditure is attributed to the resting metabolic rate.
The referenced formulas used to calculate the BRM are listed below.
RMR value represents on average 50% to 75% of a person's daily energy expenditure.
Your BMR slows down at roughly 2% every 10 years after the age of 20. This is why many people gain weight as they get older, while maintaining the same caloric intake.
BMR calculator does not take into account body composition, which is a measure of the percentages of muscle and fat composing your body. It is therefore less accurate if you have a non-typical amount of muscle (body-builders) or are an athletic person. This is because muscle burns calories, while fat does not.
The most commonly used estimation formulas in BMR calculations are: