BMR Calculator

BMR Calculator

About BMR Calculator

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain basic life functions such as breathing, circulation, cell production, nutrient processing, protein synthesis, and ion transport.

What affects your BMR?

  • Age: BMR decreases with age due to loss of muscle mass
  • Gender: Men typically have higher BMR due to more muscle mass
  • Weight: Higher weight means higher BMR
  • Height: Taller people have higher BMR
  • Body Composition: Muscle burns more calories than fat

Formula Used:

The calculator uses the Mifflin-St Jeor equation:

  • Men: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (years) + 5
  • Women: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (years) - 161

Understanding Your BMR:

  • BMR accounts for 60-75% of your daily calorie needs
  • It's the minimum calories needed to keep your body functioning
  • Never eat below your BMR for extended periods
  • Use BMR as a starting point for weight management

I know you might often think that some people eat a lot and gain no weight, while others take a small amount of meals and gain a considerable amount of weight. The reason behind this is that everyone’s body burns calories differently from each other. Now you don’t have to worry about this because this BMR calculator is the answer to all your questions. 

You can easily calculate your Basal Metabolic Rate by providing your age, height, weight, and gender. By knowing your Basal Metabolic Rate, you can easily calculate how your body is burning calories and how much food is sufficient for you to achieve your fitness goals.

Daily calorie needs based on activity level

Activity Level Calorie
Sedentary: little or no exercise
2,060
Exercise 1-3 times/week
2,361
Exercise 4-5 times/week
2,515
Daily exercise or intense exercise 3-4 times/week
2,661
Intense exercise 6-7 times/week
2,962
Very intense exercise daily, or physical job
3,262

 

Exercise: 15-30 minutes of elevated heart rate activity.
Intense exercise: 45-120 minutes of elevated heart rate activity.
Very intense exercise: 2+ hours of elevated heart rate activity.

What is BMR Calculator?

The Basal Metabolic Rate (BMR) Calculator estimates your basal metabolic rate—the amount of energy expended while at rest in a neutrally temperate environment, and in a post-absorptive state (meaning that the digestive system is inactive, which requires about 12 hours of fasting).

The basal metabolic rate 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, brain, 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 Basal Metabolic Rate measurement requires that a person’s sympathetic nervous system be inactive, which means the person must be completely rested.

Basal Metabolic Rate is considered the largest component of a human’s total caloric needs throughout the day. 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 Basal Metabolic Rate is estimated with equations summarised 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’s Equation is 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 does.

 Of these equations, the Mifflin-St Jeor Equation is considered the most accurate equation for calculating Basal Metabolic Rate , 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 expanding the settings.

The 3 equations which are being used by the calculator are:

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: The aerobic exercises, such as running and cycling, do not affect Basal Metabolic Rate , while the anaerobic exercises, such as weight-lifting, indirectly lead to a higher BMR because they build muscle mass, increasing resting energy consumption. It works on the directly proportional formula, like the higher the muscle mass higher the BMR for better functionality.

Age: The more elderly and limber an individual, the lower their Basal Metabolic Rate, 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 Basal Metabolic Rate 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 Basal Metabolic Rate 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 to more efficiently utilise 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 Basal Metabolic Rate depending on hormonal changes.

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

BMR Tests

BMR tests available online with complex formulas are not accurate for actual results for determining the individual’s BMR. It is important to consult a specialised and professional health activist for the accurate and proper Basal Metabolic Rate result of the individual. As they will calculate the Basal Metabolic Rate using a calorimetry device, handheld devices are available in many health and fitness clubs, doctors’ offices, and weight-loss clinics.

Resting Metabolic Rate

While the terms BMR and RMR are used interchangeably but there is a key difference in their definition. 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 can also be said 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 Basal Metabolic Rate showed that when controlling for 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 Basal Metabolic Rate values, but some factors that determine Basal Metabolic Rate 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 Basal Metabolic Rate estimates is just that: an estimate. 

When working towards any sort of health or fitness goal, BMR can aid in laying down the foundations, but from there on, it has little else to offer. A calculated Basal Metabolic Rate 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.