BMR Calculator: How to Lose Weight & How to Increase or Decrease

The basal metabolic rate (BMR) calculator utilizes a formula created by the World Health Organization that multiplies body weight (in kilograms) by a fixed value, and then this result is added to another pre-defined value that is based on your sex and age. 

The BMR is the quantity of energy a body at rest utilizes to maintain vital functioning, like breathing, heart rates and body heat. 

BMR can vary depend on the person's age, weight and sex. A BMR calculator is used to determine the total amount of energy the body uses per day. It can be a very useful tool when putting together a meal plan for weight gain, loss or maintenance. 

BMR calculator

This calculator is a simple way to calculate your basal metabolic rate. Insert your data below: 


How to lose weight

BMR can influence your body weight, as the the lower the amount of energy needed at rest, the less your body burns throughout the day. This can be a contributing factor to being overweight or obese. On the other hand, the higher your BMR, the more your body will burn throughout the day, which can facilitate weight loss. 

Some theories suggest that your muscle mass and body fat percentage can also influence your BMR. People who are overweight who start a diet and exercise program tend to lose weight much easier than those who are already at an ideal weight. This is because the higher your starting weight, the more energy your body will need to maintain basic vital functions. 

If you are looking to lose weight, learn more about how many calories you should eat per day

How to calculate BMR

The WHO created a formula to estimate BMR based on weight, age and sex, as outlined below: 


Woman Man

0 to 3 years old

(58.317 x weight in kg) – 31.1

(59.512 x weight in kg) – 30.4

3 to 10 years old

(20.315 x weight in kg) + 485.9

(22.706 x weight in kg) + 504.3

10 to 18 years old

(13.384 x weight in kg) + 692.6

(17.686 x weight in kg) + 658.2

18 to 30 years old

(14.818 x weight in kg) + 486.6

(15.057 x weight in kg) + 692.2

30 to 60 years old

(8.126 x weight in kg) + 845.6

(11.472 x weight in kg) + 873.1

≥ 60 years old

(9.082 x weight in kg) + 658.5

(11.711 x weight in kg) + 587.7

BMR can also be measured through through direct calorimetry testing. This method calculates energy expenditure based on the amount of carbon dioxide produced during respiration. This method can also be used to evaluate the effect of physical activity on BMR. This test is only available in specialized labs, however, and is usually not available to the average person. 

Example of BMR calculations

A BMR calculation for a 33 year old women weighing 80 kg would be as follows: (8.126 x 80 kg) + 845.6. Therefore, the basal metabolic rate for this woman is 1495.68 calories..

Difference between BMR and TDEE

A BMR is a calculation used to determine the amount of energy the body needs to perform basic vital functions, like heart beats, breathing and brain functioning, without considering the energy needed for other activities throughout the day.

TDEE, or total daily energy expenditure, is the result of the BMR multiplied by the person's activity fair. It measures the energy needed for activities like cooking, working and exercising. TEE is utilized to estimate the amount of calories needed for the entire day, and is used in maintenance, weight loss or weight gain diets. 

Learn about how many calories you burn in a day using our online calculator.

How to increase BMR

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To increase your BMR, it is important to exercise regularly at a high intensity, like swimming or running, which include strength training and HIIT. These activities stimulate muscle mass gains and help to boost respiration, which stimulates more energy burning and rest. 

It is also important to maintain a balanced diet and to prioritize vegetables, fruit, water, healthy fats and foods with thermogenic properties (like cinnamon and green tea). These can also help to boost BMR and stimulate energy burning.

Can you decrease BMR?

Not exercising or exercising very little are factors that can decrease your BMR. Also, stress can increase cortisol production, which can decrease muscle mass when it reaches high levels. Less muscle mass can eventually decrease your BMR. 

Going too many hours without eating throughout the day can also affect hormonal levels, leading to a reduced BMR in an attempt to save energy. This can lead to increased body fat and weight gain, opening the door to other health problems down the road, like obesity, fatty liver and cardiovascular problems.

It is important that going a few hours without eating is not considered to be intermittent fasting. Intermittent fasting is based on avoiding any food for at least 16 hours per day to boost metabolism. Learn more about intermittent fasting and the health benefits it can provide.