Basal Metabolic Rate (BMR) Calculator (2024)

Use this BMR calculator to easily calculate your Basal Metabolic Rate (BMR) which is how many kcal per day you need if you are just resting. It is useful when calculating calories for weight loss or gain.

Quick navigation:

  1. What is BMR?
  2. BMR formula and calculating your Basal Metabolic Rate
  3. Basal Metabolic Rate variation over time
  4. Adjusting BMR for percent body fat?
  5. Mean BMR by age and gender

What is BMR?

BMR stands for Basal Metabolic Rate, sometimes incorrectly called either "base metabolic rate" or even "basic metabolic rate". Basal here is used in the sense of "minimal", so if something is basal it is of, relating to, or being essential for maintaining the fundamental vital activities of an organism. For example, a basal diet is the absolute minimum nutrients your body needs to survive. Up to 85% of a person's daily energy expenditure goes towards sustaining the basic metabolic functions. BMR calculations are used in estimation of the energy and nutritional needs of athletes and ordinary people alike, for diets, treatment for some health conditions, weight loss diets, etc.

A definition found in the medical literature [1] is that the basal metabolic rate is the minimum energy requirement to stay alive and awake. In laboratory conditions BMR is measured by the oxygen uptake under strict conditions [2], while in most cases it is estimated based on known predictors: age, height, weight, and gender. BMR is on average 5-10% lower for women than men of almost all age groups.

First, no food is to be consumed and there must be no undue muscle exertion in the 12 hours preceding measurement. Second, the measurement is taken after 30-60 min of resting or lying quietly. Third, the measurement should take place in a room with controlled temperature at a body neutral level, that is between 22 and 26 degrees Celsius. BMR values are usually only a bit lower than the resting metabolic rate (RMR), which is a similar metric, but with less strict conditions. Read more on BMR vs RMR in the context of weight loss.

The unit for BMR in the scientific and medical literature is usually kiloCalories per square meter of body surface area (BSA) per hour: kCal·m-2·h-1. For your convenience our BMR calculator shows you the BMR in Calories per day (kcal / day) so you can read it as the minimum energy your daily diet needs to provide.

BMR formula and calculating your Basal Metabolic Rate

The formula used in our online tool for calculating BMR is:

(10 x weight) + (6.25 x height) - (5 x age) + s

where the measurements are in meters and kilograms, age is in years, and s is a gender adjustment. For example, if you are 5 foot 10 inches high 30-year old male, and your weight is 190 pounds, you need to convert your height to 1.778 meters, your weight to 86.18 kg and then plug the numbers in the formula. The adjustment s for males is 5, so the calculations would look like so: 10 x 86.18 + 6.25 x 1.778 + 5 x 30 + 5 = 1,828 kcal per day.

The formula is based on regression analyses performed over the years on varying populations and has good predictive accuracy for everyday use.

Basal Metabolic Rate (BMR) Calculator (1)

The graph above is generated using this basal metabolic rate calculator and clearly shows the difference between the averages for males and females, as well as the decline in BMR with age. Please note that this is not BMR for the average man or woman of those ages, for this, check the graph below.


Basal Metabolic Rate variation over time

The calculation using our BMR calculator is approximately accurate. Your actual rate of energy expenditure for basic metabolic processes will vary over time, depending on your circ*mstances [3]. For example:

  • If you have fever, your BMR will increase
  • Physical stress (e.g. recovering from an illness) your BMR will increase
  • Mental or emotional stress that leads to depression or lethargy, your BMR will decrease
  • Fasting lowers your BMR
  • Staying for prolonged periods of the day in a place that is hotter or colder than comfort will raise your BMR

You will note (fourth paragraph of this page) that these are things which are controlled for when measuring basal metabolic rates in medical studies. Make sure to take this into account when planning your diet plan.

Adjusting BMR for percent body fat?

Some sources [3] state that people with higher-than-average muscle mass tend to have higher-than-average BMRs. The idea is that a higher percentage of muscle mass will expend higher amounts of energy even when resting, leading to higher basal caloric needs. Other such as Marra et al. [4] refute this notion, demonstrating in a large-scale study that nor body fat percentage nor lean body mass are good predictors of BMR and that equations constructed specially for overweight and obese persons do not perform better than others. We are not aware of good regression equations that can be applied to adjust for that factor.

Mean BMR by age and gender

The graph and table with mean BMR below are calculated based on mean weight and height data from the U.S. NCHS National Health and Nutrition Examination Survey (2011-2014) [5]. The average basal metabolic rate is estimated using this Basal metabolic rate calculator.

Basal Metabolic Rate (BMR) Calculator (2)

Mean (average) BMR by age (Calories)
Age or age groupMale BMR (kCal·m-2·h-1)Female BMR (kCal·m-2·h-1)
5 years104.4490.96
6 years98.8085.91
7 years91.5882.95
8 years87.2476.82
9 years85.0971.25
10 years77.9568.74
11 years71.1765.09
12 years70.4761.09
13 years65.0162.25
14 years63.3560.42
15 years61.5658.23
16 years60.5757.87
17 years60.3856.74
18 years57.9856.70
19 years58.8065.04
20-29 years55.9953.26
30-39 years53.1350.33
40-49 years51.5148.81
50-59 years50.5247.09
60-69 years49.1846.08
70-79 years48.8044.78
80+ years49.6946.32

The chart and table are calculated using the formula described above. To convert from the table to daily basal metabolic rate, you need to multiply by the estimated body surface area (BSA) and then by 24.

It is obvious from the table that between the age of 5 and late adulthood a human's basal metabolic rate decreases roughly 50%, on average. Similarly, calories in a daily diet are usually adjusted to account for the decreased energy expenditure.

References

1 Katch V.L., McArdle W.D., Katch F.I (2011) "Essentials of Exercise Physiology", fourth edition

2 Henry CJK, (2005) "Basal metabolic rate studies in humans: Measurement and development of new equations.", Public health nutrition. 8:1133-52.

3 U.S. National Institutes of Health (2007) "Information about Energy Balance", NIH Curriculum Supplement Series

4 Marra M., et al. (2017) "Prediction and evaluation of resting energy expenditure in a large group of obese outpatients", International Journal of Obesity 41:697–705

5 US NCHS (2016) "National Health and Nutrition Examination Survey (2011-2014)" DHHS Publication No. 1604, s.3, N 39

Basal Metabolic Rate (BMR) Calculator (2024)

FAQs

How accurate is the BMR calculator? ›

While useful, BMR calculators are not 100% accurate. Although the Mifflin-St. Jeor equation is known as one of the most accurate calculators, its result can be off by around 10% of your true BMR. Also, without including your activity level in the equation, you're not actually calculating your daily calorie needs.

What is the most effective BMR calculator? ›

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.

What is the most accurate RMR calculator? ›

The Mifflin-St. Jeor equation is considered a more accurate and reliable RMR calculation method than the Harris Benedict equation takes diverse body compositions and ethnicities into consideration.

How to calculate BMR correctly? ›

Calculate Basal Metabolic Rate

Your basal metabolism rate is produced through the following basal metablic rate formula: Men: BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) – (5.677 x age in years) Women: BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) – (4.330 x age in years)

What is a good BMR for my age? ›

How to Calculate your ideal BMR?
AgeMale (calories per hour)Female (calories per hour)
20–2939.537.0
30–3939.536.5
40–4938.536.5
50–5937.535.0
2 more rows
Jun 3, 2021

Do I need to eat less than my BMR to lose fat? ›

BMR is a component of your TDEE, but it is NOT the amount of calories you should eat to lose weight. BMR is the amount of calories your body needs to "keep the lights on" and ensure you live to fight another day. To lose weight, you need to eat about 15-20% less than your TDEE.

What is the strongest predictor of BMR? ›

Fat-free mass is the best predictor of measured BMR.

How to lose weight if your BMR is 1400? ›

How Many Calories Should I Eat Daily to Lose Weight? For example, if your BMR is 1,400 (the average for American women) and you are moderately active, your AMR would be 2,170 (1,400 x 1.55). Since a pound of fat is equal to 3,500 calories, you would need to cut 500 calories per day to lose a pound per week.

Is your BMR higher if you are overweight? ›

If you have a slow metabolism or slow BMR, your body needs fewer calories to keep it going. A fast metabolism does not necessarily lead to thinness. In fact, studies show that people with overweight/obesity often have fast metabolisms. Their bodies need more energy to keep basic body functions going.

Should I eat less calories than my RMR? ›

If you consume fewer calories than your RMR requires, you may not provide enough fuel for these essential bodily functions. This could lead to fatigue, nutrient deficiencies, weakened immune system, and other health problems over time.

How many calories do 10,000 steps burn? ›

How many calories do 10,000 steps burn? Most people burn 30-40 calories per 1,000 steps they walk, meaning they'll burn 300 to 400 calories by walking 10,000 steps, Hirai says.

Why is my BMR higher than my RMR? ›

The key difference, while the BMR is based on being at rest for 24-hours, the RMR includes movement of light activities. These activities include eating, using the restroom, walking, stretching, etc. Since movement is included in the RMR, your resting metabolic rate will always be slightly higher than your BMR.

Which BMR calculator is best? ›

Today, experts consider the Mifflin-St Jeor equation to be the most accurate, which is why we use it in our calculator tool above.

What is the most accurate way to measure basal metabolic rate? ›

You'll breathe into a special mask called a calorimeter that covers your mouth and/or nose. The mask uses your breath rate to measure the calories you burn. You'll need to sleep at the lab overnight to get an accurate BMR measurement. The number of hours you sleep and the temperature of the room can affect your BMR.

Why is my BMR so low? ›

Factors that affect our BMR

Amount of body fat – fat cells are 'sluggish' and burn far fewer kilojoules than most other tissues and organs of the body. Crash dieting, starving or fasting – eating too few kilojoules encourages the body to slow the metabolism to conserve energy.

What happens if I eat the same calories as my BMR? ›

If you eat the same number of calories as your BMR and you are not active, you will maintain your weight, not lose it. You should never eat less than your BMR as this is the basic number of calories your body needs to perform basic functions like breathing and digestion.

Is basal metabolic rate real? ›

Your metabolism regulates how your body uses energy for these functions. Basal metabolic rate (BMR) and resting metabolic rate (RMR) both measure the amount of energy —‌in calories —that your body needs to stay alive and function properly.

Can a scale really measure BMR? ›

Many smart scales also measure other key biometrics, including visceral fat, water percentage, bone density, muscle mass, and BMR (basal metabolic rate).

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