BMR Calculator
Your basal metabolic rate (BMR) is the energy your body spends on the vital functions it keeps going even at complete rest. This tool estimates a BMR value from your age, sex, height and weight.
Your heart beating, your breathing and the maintenance of your body temperature all use energy even when you are doing nothing at all. BMR is the name of that basic expenditure, and in most people it makes up the largest part of daily energy use. This tool helps you estimate that value with a widely accepted equation, without the need for measuring equipment. If you are wondering about your total daily expenditure, you can carry on with the TDEE Calculator.
Tool
Frequently asked questions
What is the difference between BMR and TDEE?
BMR estimates expenditure at rest only; TDEE adds daily movement and exercise on top of it. If you are wondering about your daily energy needs, TDEE is the more inclusive indicator.
My result came out different from my friend’s — is that normal?
Yes. Because the equation works from age, sex, height and weight, every difference in those values changes the result; and even with identical inputs, real metabolism can vary from person to person.
Is it a problem if my BMR value comes out low?
Not on its own. A low or high estimate says nothing about your health by itself. If you have a complaint such as constant tiredness, the answer should be sought in a medical examination rather than in a calculator.
Why is the Mifflin-St Jeor equation used?
It was chosen because current research finds it one of the practical equations that give the most consistent results for estimating resting metabolism.
Method and formula
The calculation is based on the Mifflin-St Jeor equation, often used in research to estimate resting metabolism: for men, 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5; for women, the same expression ends with −161 instead of +5. The result is shown in kcal/day. This is not a measurement but an estimate resting on population averages, so the figure should be read as a starting point rather than an exact number.
How to read the result
The value produced shows roughly the energy you would spend if you did not move at all during the day. Your real daily expenditure is always higher than this, because movement, exercise and digestion are added on top. It is normal for two people of the same age, height and weight to have different real values; muscle mass, genetics and health status all shift the result from person to person.
Limits
- The equation rests on population averages; individual deviation can be ten per cent or more.
- It does not distinguish between muscle and fat; in people with high muscle mass the real value may come out above the estimate.
- In situations such as thyroid problems, certain medicines and pregnancy, the estimate loses its reliability.
- True resting metabolism can only be measured under laboratory conditions (indirect calorimetry).
Safety boundary
This tool is for information; it does not take the place of a medical assessment. If you need to adjust your diet because of a health condition, consult your doctor or a dietitian.
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