Basal Metabolic Rate and Daily Energy Expenditure
Basal Metabolic Rate
Our whole life depends on how much energy we have. It is based on our metabolism, the sum of the human body’s chemical processes.

To get a real picture it is important that our body weight is based on the energy balance which comes from the energy intake and energy usage during the day. If energy intake is higher than energy usage for a long time, than body weight increases, if energy usage is higher than energy intake, you lose weight. Depending on the energy content of each food, you can regulate your own weight and energy level.

The basal metabolic rate is given in calories or Joules (1 cal=4,184 Joule).

For one hour and one square metre the value of the Basal Metabolic Rate is 40 kcal/hr/m² or 167 kJ/hr/m², an average person’s (approx. 170-175 cm high, 60-70 kg) basal metabolic rate for one hour is 70 kcal/hr or 293 kJ/hr and for one day it is 1700 kcal/day or 7113 kJ/day.

The BMR is modified by many factors. One of them is age – newborn babies have low BMR, approx. 25 kcal/hr/m², a few years old child has 55 kcal/hr/m², and BMR decreases later on, with 1-1.5 kcal/10 years, so 70-74 year-old people’s BMR is around 35 kcal/hr/m².

Furthermore, BMR varies according to sex, climate and your nourishment status, but is not really affected by physical activity level.

Physical activities need much more energy than just sitting in front of the PC or TV, but they can help you to liberate some energy as well. To get information about your energy needs we provide you with two calculators of which one is a basal metabolic rate (BMR) calculator. This will give you your basic energy output level - what we could measure in a closed room if you would have done nothing, just waken up after 12-14 hours of starvation, on basic temperature (20 °C if you are dressed or 28 °C without clothes), without any psychological stress or emotion as well as any muscle work, in a lying position, measuring the heat production. This calculation needs you to get acquainted with another concept which is called body surface area (BSA). It is the measured or calculated surface of the human body. There are some formulas how to calculate it, maybe the most accurate is the oldest one, that of DuBois and DuBois (1916). We will use this one.

Normal values

Although ‘Normal’ BSA, or rather we could use the word ‘average’, is only 0.25 m² for a baby, to the date we reach adulthood it grows to 1.73 m².
Let’s calculate your Basal Metabolic Rate!
We offer you two ways to get the results of your own BMR level. For both of them you will need to enter here your gender, age, weight and height.
Gender:
Age:
Weight:
Height:
Your BSA according to Dubois&Dubois:
Your Basal Metabolic Rate based on your Body Surface Area:
Your Basal Metabolic Rate according to the recommendation of WHO: