Basal Metabolic Rate BMR Calculator


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BMR Calculator




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Considering how calorie-obsessed we have all become, the word "metabolism" immediately draws attention. In the course of your work as a certified personal trainer, you may be questioned about this subject from time to time.

Fat-to-fit or "flab-to-fab" is what the general public associates with increasing your metabolism. Enhanced caloric expenditure, improved lean body mass, better fat utilization and total weight reduction are all factors that contribute to this result

Considering the importance of our RMR, it's obvious that so much emphasis is paid to this. In the meanwhile, let's examine the components of the overall daily energy expenditure before diving into RMR (TDEE). Articles like this:

  • Energy Consumption on a Daily Basis
  • When you're at rest, what is your metabolic rate?
  • Making use of the RM
  • RMR Unpredictable Factors
  • Constraints on RMR
  • Achieving Optimal Resting Metabolic Rate in Starvation States

Total Daily Energy Expenditure

The term metabolism refers to the biological processes that are necessary to sustain life in scientific terms. The average person's daily energy expenditure and how it affects the energy in vs. energy out equation are the most important considerations. There are three main parts to our TDEE:

  • At rest, your body needs a certain amount of energy, which is known as your resting metabolic rate (RMR).
  • TEF: the energy cost of chewing, swallowing, digesting, absorption and storing food.
  • Energy expenditure from physical activity (TEPA) and non-exercise thermogenesis (NEAT) are two components of the thermogenic impact of activity (TEPA).*

The following is not a kind of exercise: There is a wide variety of activities that contribute to a person's thermogenesis, from simply standing to fidget and moving about. NEAT is not the same as METS.

What is the RMR that we have? Is it up to us, or is it already set in stone? Let's take a closer look at these issues.

The total amount of calories expended by your body when it is entirely at rest is known as your resting metabolic rate. Inhalation, circulation, and organ function are all supported by RMR. A 1% increase in fat mass results in a reduction of 0.01 kcal/min in the amount of calories burned per minute.

Basal metabolic rate Calculator

Calculating one's energy consumption is easy using direct calorimetry, which measures the amount of heat generated by a person housed in a tiny chamber. Indirect calorimetry uses gas analysis to estimate energy expenditure by measuring oxygen usage rates.

These methods are costly, time-consuming, and difficult to get precise RMR estimations, despite the fact that they are correct. As a consequence, RMR estimation methods have become more accessible and inexpensive during the previous century. They use a variety of methods to get this number.

In today's world, mathematical formulae are among the most used ways. A calorie calculator may be found online, via an app, or on a wearable device. You may figure out your RMR by using this online calculator: National Association of Sports Medicine's online calorie calculator

Basal metabolic rate Calculator - Harris and Benedict Equation

It is still commonly used today, thanks to the Harris and Benedict (H&B) equation established in 1918 and updated in 1984.

established in 1918 and updated in 1984. As a result, the terms "resting metabolic rate" and "basal energy expenditure" have come to be used interchangeably, despite the fact that they were designed to assess different things. Relative resting metabolic rate (RMR) is a less restrictive method of measuring resting metabolic rate (BMR) after an overnight fast.

Male and female H&B equations have been recalculated as follows:

  • Over the course of their lives, men's weight, height, and age are all taken into account to come up with their total body mass index (BMI). 447.593 + (9.247 kg + (3.098 cm + (4.330 years)) - (4.330 years)

BMR or RMR is the amount of calories a 38-year-old female, who is 5'6" (167.6 cm) tall and weighs 145 pounds (65.9 kg), burns per day.

Mifflin-St Jeor Formula

To provide a more accurate estimate of RMR, the Mifflin-St. Jeor formula was devised in the 1990s .

The equations for males and females are:

  • A man's weight in kilograms is equal to his height in centimeters multiplied by his age in years. 10 kg + 6.25 cm + (5 years of age) = weight for women a total of 161

The RMR for a girl would be 1,356 calories if the same example and calculation were used.

Potential Errors

Over a one-year period, this miscalculation adds up to roughly six pounds of energy or body weight (i.e. 55 calories).

The assumption that all people of the same gender, age, height, and weight have the same RMR is likewise incorrect, as these calculations assume. RMR is heavily influenced by your lean body mass, so keep an eye on it at all times.

In spite of the fact that the Katch-McArdle and Cunningham formulae are derived from lean mass rather than total body weight, they need an accurate assessment of lean mass. These calculations include a wide range of errors, ranging from 10% to 36% in obese persons (H&B) .

In spite of updated equations (such as Oxford equations), they are still susceptible to a variety of errors.

Uncontrollable RMR Factors - Basal metabolic rate Calculator

Only a few things are beyond our control, including our age, our genes, and even our own biological adaptations.


We should expect a 2-percentage-point decline in our resting metabolic rate (RMR) in the decade after peak growth in both women and men (late teens to early twenties).

Assuming that RMR accounts for 60% to 75% of TDEE, this means that the typical adult consumes around 25 to 30 calories per day or about 212-to-3 pounds (1.1-1.4 kg) each year.

Genetics and Epigenetics

Additionally, genetics and epigenetics may have a crucial influence. Scientists have found more than 100 genes that are linked to obesity.

Low satiety is connected with the FTO gene, which is associated with fat accumulation and obesity.

Consuming greater quantities, choosing fattier and sweeter meals, and snacking more often are all symptoms of an eating disorder characterized by poor satiety.

RMR may be altered by as much as 160 calories per day by the FTO gene, which equates to almost 17 pounds (7.5 kg) in a year.

Our genetic expression may be altered without altering our DNA sequence via epigenetics, a branch of genetics.

Anxiety and depression are two of the most common mental health issues in the United States today.

For example, studies have shown that changes in TDEE may alter RMR by up to a few percentage points or 60 to 75 calories per day, depending on how food intake and metabolism are altered. Additionally, genetics and epigenetics may have a crucial influence. Scientists have found more than 100 genes that are linked to obesity.

Low satiety is connected with the FTO gene, which is associated with fat accumulation and obesity.

Consuming greater quantities, choosing fattier and sweeter meals, and snacking more often are all symptoms of an eating disorder characterized by poor satiety.

Over the course of a year, this FTO gene may change RMR by up to 160 calories per day, which equates to roughly 17 pounds (7.5 Kg).

The study of inheritable changes in our genetic expression that occur without altering our underlying DNA sequence is known as epigenetics.

Regular and natural, it is impacted by factors such as age, environment, nutrition, location and lifestyle.

For now, scientists are investigating the relationship between epigenetics and TDEE to see whether it affects food intake or metabolic rate (RMR) by 5 to 10 percentage points, or 60 to 75 calories per day.

Uncontrollable RMR Factors - Basal metabolic rate Calculator

There is no limit to what may be done, although most fitness experts focus on exercise, macronutrients, calories and other stimulants as their primary methods of weight loss.


Caffeine and capsaicin, for example, have been shown to temporarily increase thermogenesis by 4–5 percent, which equates to 15–25 calories per day

Genetics and Epigenetics

Building lean body mass is a good way to increase RMR. Humans reach their peak muscular mass between the ages of 28 and 32, after which time they begin to lose muscle mass.

Age-related muscle loss may be slowed by the capacity to maintain or even increase muscular mass. Muscle mass gains of 2 to 4 pounds may increase metabolism by 7 to 8 percent, resulting in an additional 90 to 110 kcal to TDEE every day or 9 to 11 pounds over the course of a year.


Your RMR may be impacted adversely even if you have sleep debt (which is to say, a lack of sleep).

Low Caloric Intake

RMR may be suppressed by as much as 20%, according to studies conducted over the course of three decades on the effects of consuming extremely few calories (e.g., starvation, 800-calorie diets).

Cortisol may have a negative influence on thyroid hormone production when it is increased for an extended period of time, resulting in a decrease in metabolism. It's also possible to lose muscle mass in hunger circumstances and hence lower RMR as a result.

As an example, for a person with an RMR of 1,200 to 1,500 calories a day, a 20% suppression may result in 240 to 300 calories per day, or 25 to 31 pounds per year. Follow the link for further information on hormone synthesis and its connection to metabolic function.