BMR Calculator - Basal Metabolic Rate Calculator

 

BMR Calculator

Basal Metabolic Rate (BMR) is an effective tool to measure your minimum energy expenditure while you are resting. Your BMR determines the minimum calories youe body needs to accomplish basic functions

What Is BMR(Basal Metabolic Rate)?

BMR stands for Basal Metabolic Rate. It is the rate of energy expenditure per unit time at rest. BMR can only be measured in endothermic animals. The amount of energy expenditure is often measured by oxygen consumption.

How To Calculate Your BMR Manually

To calculate BMR, you need to check your height and weight and analyze your activity level. If you are aware of all these parameters, you can calculate your BMR manually using the following equations.

BMR For Men

BMR (metric) = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5

BMR (imperial) = (4.536 × weight in pounds) + (15.88 × height in inches) –(5 × age) + 5

BMR For Women

BMR (metric) = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

BMR (imperial) = (4.536 × weight in pounds) + (15.88 × height in inches) – (5 × age) – 161

Why Does Your BMR Matter?

BMR is the amount of energy needed to perform basic bodily functions while resting, like breathing, blood circulation, regulation of body temperature, cell growth, brain and nerve functions, contraction of muscles, etc. About 70% of calories consumed every day is utilized for basal metabolism.

If you lead a sedentary lifestyle with little to no exercise, you should eat minimum calories according to your BMR. If you are physically active and use more of your muscles, your calorie consumption should be more than the BMR.

Having a high BMR means you have a strong metabolic rate. This builds your lean fat mass and muscle mass, which are important parameters to stay fit and healthy.

How To Use BMR Calculator To Lose Weight

Knowing your BMR is an important factor if you want to lose weight. Once you know your BMR and the calories you expend while doing exercise, you can easily improve your calorie intake.

If you want to lose weight, you need to reduce your intake by 500 calories per day, which is enough to lose 1-2 pounds per week or so based on your activity level.

Are BMR tests accurate?

Online BMR tests give average data to analyze how much you need to consume per day. Consult a medical practitioner and get your BMR checked by using calorimetry device for exact results.

Difference Between BMR And RMR

RMR (Resting Metabolic Rate) is the rate at which your body expends calories while you are in relaxed or sleeping, while BMR measures the minimum calorie expenditure while you are resting or inactive but awake.


The basal metabolic rate (BMR) is the amount of energy needed while resting in a temperate environment when the digestive system is inactive. It is the equivalent of figuring out how much gas an idle car consumes while parked. In such a state, energy will be used only to maintain vital organs, which include the heart, lungs, kidneys, nervous system, intestines, liver, lungs, sex organs, muscles, and skin. For most people, upwards of ~70% of total energy (calories) burned each day is due to upkeep. Physical activity makes up ~20% of expenditure and ~10% is used for the digestion of food, also known as thermogenesis.


The BMR is measured under very restrictive circumstances while awake. An accurate BMR measurement requires that a person's sympathetic nervous system is inactive, which means the person must be completely rested. Basal metabolism is usually the largest component of a person's total caloric needs. The daily caloric need is the BMR value multiplied by a factor with a value between 1.2 and 1.9, depending on activity level.


In most situations, the BMR is estimated with equations summarized from statistical data. The Harris-Benedict Equation was one of the earliest equations introduced. It was revised in 1984 to be more accurate and was used up until 1990, when the Mifflin-St Jeor Equation was introduced. The Mifflin-St Jeor Equation has been shown to be more accurate than the revised Harris-Benedict Equation. The Katch-McArdle Formula is slightly different in that it calculates resting daily energy expenditure (RDEE), which takes lean body mass into account, something that neither the Mifflin-St Jeor nor the Harris-Benedict Equation do. Of these equations, the Mifflin-St Jeor Equation is considered the most accurate equation for calculating BMR with the exception that the Katch-McArdle Formula can be more accurate for people who are leaner and know their body fat percentage. You can pick the equation to be used in the calculation by expand the settings.

The three equations used by the calculator are listed below:

Mifflin-St Jeor Equation:
For men:
BMR = 10W + 6.25H - 5A + 5
For women:
BMR = 10W + 6.25H - 5A - 161

Revised Harris-Benedict Equation:
For men:
BMR = 13.397W + 4.799H - 5.677A + 88.362
For women:
BMR = 9.247W + 3.098H - 4.330A + 447.593

Katch-McArdle Formula:
BMR = 370 + 21.6(1 - F)W

where:

W is body weight in kg
H is body height in cm
A is age
F is body fat in percentage

BMR Variables

Muscle Mass – Aerobic exercise such as running or cycling has no effect on BMR. However, anaerobic exercise, such as weight-lifting, indirectly leads to a higher BMR because it builds muscle mass, increasing resting energy consumption. The more muscle mass in the physical composition of an individual, the higher the BMR required to sustain their body at a certain level.

Age – The more elderly and limber an individual, the lower their BMR, or the lower the minimum caloric intake required to sustain the functioning of their organs at a certain level.

Genetics – Hereditary traits passed down from ancestors influence BMR.

Weather – Cold environments raise BMR because of the energy required to create a homeostatic body temperature. Likewise, too much external heat can raise BMR as the body expends energy to cool off internal organs. BMR increases approximately 7% for every increase of 1.36 degrees Fahrenheit in the body's internal temperature.

Diet – Small, routinely dispersed meals increase BMR. On the other hand, starvation can reduce BMR by as much as 30%. Similar to a phone that goes into power-saving mode during the last 5% of its battery, a human body will make sacrifices such as energy levels, moods, upkeep of bodily physique, and brain functions in order to more efficiently utilize what little caloric energy is being used to sustain it.

Pregnancy – Ensuring the livelihood of a separate fetus internally increases BMR. This is why pregnant women tend to eat more than usual. Also, menopause can increase or decrease BMR depending on hormonal changes.

Supplements – Certain supplements or drugs raise BMR, mostly to fuel weight loss. Caffeine is a common one.

BMR Tests

Online BMR tests with rigid formulas are not the most accurate method of determining an individual's BMR. It is better to consult a certified specialist or measure BMR through a calorimetry device. These handheld devices are available in many health and fitness clubs, doctor offices, and weight-loss clinics.

Resting Metabolic Rate

While the two are used interchangeably, there is a key difference in their definitions. Resting metabolic rate, or RMR for short, is the rate at which the body burns energy in a relaxed, but not fully inactive state. It is also sometimes defined as resting energy expenditure, or REE. BMR measurements must meet total physiological equilibrium while RMR conditions of measurement can be altered and defined by contextual limitations.

Modern Wisdom

A 2005 meta-analysis study on BMR* showed that when controlling all factors of metabolic rate, there is still a 26% unknown variance between people. Essentially, an average person eating an average diet will likely have expected BMR values, but there are factors that are still not understood that determines BMR precisely.

Therefore, all BMR calculations, even using the most precise methods through specialists, will not be perfectly accurate in their measurements. Not all human bodily functions are well understood just yet, so calculating total daily energy expenditure (TDEE) derived from BMR estimates are just that, estimates. When working towards any sort of health or fitness goals, BMR can aid in laying down the foundations, but from there on it has little else to offer. A calculated BMR and thus TDEE may result in unsatisfactory results because of their rough estimates, but maintaining a daily journal of exercise, food consumption, etc., can help track the factors that lead to any given results and help determine what works, as well as what needs to be improved upon. Tracking progress in said journal and making adjustments over time as needed is generally the best indication of progress towards reaching personal goals.