Sports, nutrition, weight loss, exercise

How is body mass index measured. How to Calculate Body Mass Index (BMI)

Ideal weight is an average standard that is calculated based on data from a large number of people. But all people are different. Lifestyle, food culture, nationality and body type - all this affects the ideal weight. For example, the normal weight of people with a strong physique will be 2-3% higher than that of people with an average body. And the norm for thin people is 3-5% less. Therefore, it is not necessary to strive specifically for the ideal weight, which shows weight calculator. It is enough if your weight is within the calculated range.

Beyond the weight calculator calculates BMI- body mass index (ideal weight), which is widely used to determine the degree of correspondence between body weight and height.

How to calculate your ideal weight (BMI) yourself

BMI \u003d M: R 2, where

M - body weight in kg

P - height in meters

An example of calculating the body mass index: M (weight) - 78 kg, P (height) - 1.68 m

BMI = 78: 1.68 2 = 27.6

From the table below, you can see that a BMI of -27.6 corresponds to being overweight.

Table of interpretation of BMI indicators

In the case of a strong deviation from the norm, it is time to seriously think about correcting your weight. With reduced weight, dystrophy develops. In the modern civilized world, its cause is usually intentional malnutrition. The desire to have an unnaturally slender figure can result in a violation of both the psyche and physical health - the ability to work decreases, the skin dries, hair falls out. All this comes from a lack of substances necessary for the body.

However, their excessive excess also does not lead to anything good. A huge number of people suffer from obesity. Excess weight greatly increases the risk of kidney and gallbladder stones, joint deformities, impotence, myocardial infarction and many other diseases. The whole body works with overload, moving masses of fat in space that are not provided for by the design of the human body. Not surprisingly, the life expectancy of obese people is on average 6-8 years less than that of the rest.

What is body mass index and how to calculate it for women by age is a very popular topic, one might say hackneyed. Slenderness today is actually a synonym for beauty and certainly an integral part of health. Insufficient weight, as well as its excess, negatively affect the work of all organs and systems of the body. But how do you know if your weight is within the normal range? After all, the concept of the norm will be different for people of different sex, constitution, age. The most accurate today is the formula by which the body mass index is calculated. Still calculating your ideal weight using the "height minus 110" formula? This is correct, but not for everyone. After all, this way you do not take into account many important indicators, for example, the type of figure and age. The body mass index helps to calculate the ideal weight much more accurately. Let's figure out what it is.

What is Body Mass Index (BMI)?

Body mass index is an indicator that characterizes the ratio of height and weight. This also takes into account age and gender, which makes it possible to obtain differentiated data for different groups of people.

This indicator is used by doctors to assess the state of the human body - the presence of obesity or dystrophy and their degree. The calculation of BMI is quite simple, it can be done at home. Perhaps it is the result of calculating the BMI that will become your starting point on the path to a normal body weight.

The first BMI formula appeared in the 19th century, its author was the Belgian Adolf Quetelet. In the future, many scientists were engaged in refining the formula, and today the BMI value can be calculated according to Quetelet, Brock, Breitman, Oder, Noorden, etc.

Most often, it is the basic formula that is used, in which the indicator is equal to the ratio of body weight to height squared (height is indicated in meters). For example, a woman with a height of 165 cm and a weight of 50 kg should calculate BMI as follows: BMI \u003d 50 * (1.65 * 1.65). The final value of BMI = 18.36.

After that, you get the finished figure. As a rule, a weight in the range of 19-25 is considered normal, but this is an average indicator. It is not suitable for minors, the elderly and professional athletes. It turns out that just calculating the body mass index for a woman, even taking into account age, is not enough to understand the state of her body. Decoding of indicators is done using special tables.


What does BMI depend on?

Since the only indicators used in the calculation are height and weight, the final result gives only a general idea of ​​\u200b\u200bthe state of the body.

It is quite obvious that the weight of a healthy girl at 20 and a woman at 55 with the same height is rarely equal. This does not mean that one of them “falls out” of normality. No, just to calculate body mass index by age for a woman over 45 years old, the basic formula is used, but a different interpretation of the results. For every 10 years of life (starting from the age of 24), the normal limit increases by 1 unit.

That is, a normal BMI at the age of 19-24 years is 19-24, 25-34 years is 20-25, etc.


In addition, the appearance of a person depends not only on the actual weight, but also on the ratio of the amount of musculoskeletal and adipose tissue. The normal BMI of athletes is much higher than that of untrained people with weakly expressed muscles.

The interpretation of BMI will also depend on the type of figure, which is determined by measuring the girth of the wrist. This is how thin-boned, normo-boned and wide-boned types are distinguished.

Men have more muscle than women, which means that the body mass index will be higher. The difference between men and women is visible at any age, so the calculation results for different sexes are interpreted in separate tables.

Why do you need to know how to calculate body mass index?

Feeling your own fullness or thinness is very subjective, someone considers himself a fat man, being more than slender, and someone does not consider 10-20 kg of fat hanging on his sides to be superfluous. The BMI calculation was created to help you understand how overweight you are and how much your weight fits into the average statistical norm.


In medicine, the calculation of BMI is used to adjust the doses of drugs, and in everyday life - to control body weight.

Of course, we all strive to look good and in the struggle for beauty we often go to extremes. For example, girls often bring themselves to exhaustion by strict diets or a complete refusal to eat because they think they are not slim enough.

The body mass index allows you to understand whether you are within the normal range, and in which direction you should work on yourself - to reduce weight or, conversely, build muscle.

BMI not only helps to determine the presence of problems with weight, but also shows their degree. Depending on how much the BMI indicator deviates from the norm, the types and intensity of the load, as well as an individual diet, are selected.

Lack of weight is also fraught with serious health problems - metabolic disorders, water-salt balance, hormonal disruptions, beriberi, amenorrhea, osteoporosis. Complications due to these diseases can even lead to death, so it is very important to pay close attention to your weight and health.

At the same time, you should not blindly focus only on numbers - always analyze how comfortable you feel in your body, what symptoms or complaints you have. A slight deviation from the norm may be an individual feature of your body. If you are full of energy, feel good and are satisfied with your health, you definitely shouldn’t reshape yourself to please numbers and indicators.

How to calculate body mass index for women based on age?

So, the standard formula for calculating BMI is suitable for young women around the age of 20-40 years.


If you do not want to fool around with squaring and dividing numbers, you can use the ready-made BMI table. The advantage of such tables is that there are different options for men and women, separate tables for athletes, pregnant women and women over the age of 45.

For older women, there is a simplified formula for calculating BMI: height in centimeters minus one hundred. This is how weight is calculated for women of average build.

If your type is asthenic, subtract 10% from the result. For hypersthenics, the result, on the contrary, should be increased by 10%. It is necessary to make accurate measurements of height and weight in the morning on an empty stomach after visiting the restroom.

As a rule, in the morning our weight is less than the “evening” weight by about a kilogram and a half (due to edema and food eaten during the day), and growth in the morning, on the contrary, is a couple of centimeters higher due to the fact that the spine is in a horizontal position during the night “stretches”, the intervertebral cartilages return to their normal state. But in the evening we are tired, the spine is compressed and, accordingly, growth is less.

Regardless of the formula for calculating the weight that you use, if there are serious deviations from the recommended weight, it is urgent to correct the diet - on your own or with the help of a nutritionist.

Body mass index is the optimal ratio of weight and height. Everyone wants to be slim and beautiful, but the problem of overweight for a modern person is one of the most pressing today. How to solve it?

Today we are witnessing a real fitness boom. Everyone tries to "build" their body in full accordance with the canons of beauty. Physical education tightens worse than drug addiction, so many do not get out of the gym at all, furiously burning every extra gram, as it seems to them.

But is it right? Excess weight, of course, becomes the cause of many diseases of the musculoskeletal and cardiovascular systems. However, the lack of weight leads to the same result.

How to become perfect? Everyone knows: we take height in centimeters and subtract 110 from this figure. What happened is the optimal weight.

For example, a woman with a height of 176 centimeters weighs 66 kilograms. She is perfect: 176 - 110 = 66.

But doesn't this approach seem too exaggerated? After all, only one parametric indicator is used - growth. And people are different from each other - age and physique are different for everyone. To take into account all these indicators, you need to apply a different formula. It is called the body mass index (BMI) and indicates the optimal ratio of height and weight.

This is what the body mass index looks like (table for women).

Height in cm Age
20-29 30-39 40-49 50-59 60-69
150 48.9 53.9 58.5 55.7 54.8
152 51.0 55.0 59.5 57.6 55.9
154 53.0 59.1 62.4 60.2 59.0
156 55.8 61.5 66.0 62.4 60.9
158 58.1 64.1 67.9 64.5 62.4
160 59.8 65.8 69.9 65.8 64.6
162 61.6 68.5 72.2 68.7 66.5
164 63.6 70.8 74.0 72.0 70.7
166 65.2 71.8 76.6 73.8 71.4
168 68.5 73.7 78.2 74.8 73.3
170 69.2 75.8 79.8 76.8 75.0
172 72.8 77.0 81.7 77.7 76.3
174 74.3 79.0 83.7 79.4 78.0
176 76.8 79.9 84.6 80.5 79.1
178 78.2 82.4 86.1 82.4 80.9
180 80.9 83.9 88.1 84.1 81.6
182 83.3 87.7 89.3 86.5 82.9
184 85.5 89.4 90.9 87.4 85.8
186 89.2 91.0 92.9 89.6 87.3
188 91.8 94.4 95.8 91.5 88.8
190 92.3 95.8 97.4 95.6 92.9

What does BMI depend on?

It should not be assumed that the BMI table for women can replace the beauty formula. People with the same BMI look different, which, in general, is logical: each organism has individual anthropometry. Physiologists distinguish three types of physique.

  1. The thin-boned type is easy to identify by conspicuous long legs and arms, a thin neck.
  2. The normo-bone type is people with familiar, one might say, classical proportions.
  3. The broad-boned type is defined by a high diaphragm and broad chest and shoulders.

Determining your body type is very easy: you just need to measure the circumference of your wrist just below the bone. The norm for the normo-bone type will be from 16 to 18 cm. If the result is less than 16 cm, then you are a hyposthenic (thin-boned type). If you are over 18, you are hypersthenic, or a person with a large-boned body type.

Naturally, for different body types, the ideal weight will be different. A mass that is normal for, say, a hypersthenic will be insufficient for a person with a normal-boned physique.

BMI for women, taking into account age, will also differ from the generally accepted one. With age, the body no longer burns fat so intensively, so the older you get, the more difficult it is to get rid of the layer on the hips or abdomen. Therefore, when calculating BMI, it is necessary to take into account how old a person is.

Why you need to know BMI

This value is necessary for those who follow their figure. Of course, you can exhaust yourself with diets or exhausting workouts - to each his own. But to what weight limits do we need to keep the diet? After all, it’s so short to lose weight and to anorexia. The answer to the question will be BMI: this is the indicator that you need to strive for.

How to calculate BMI

It was developed by the Belgian anthropologist Quetelet in the middle of the 19th century. However, modern doctors still use it, determining the level of obesity or dystrophy in their patients. Naturally, over the course of two centuries, the Quetelet method has undergone certain adjustments; other scientists have created their own calculation tables based on BMI. However, all the changes were only beneficial, since they allow you to most accurately calculate the ideal weight for each person.

Quetelet proposed to use a more complex formula to calculate the optimal mass: the weight must be divided by the square of height in meters. The result is a body mass index, the value of which corresponds to a certain state of the body - a mass deficit, a norm or its excess:

  1. Weight deficit - from 18.49 and below (below 16 - a critical deficit).
  2. The norm is from 18.50 to 24.99.
  3. Overweight - from 25 to 29.99 (from 30 and above - obesity).

That is, for the same woman (176 cm, 66 kg), the body mass index will be: 66: 1.762 = 21.35. Her BMI is within the normal range. But BMI by age is not taken into account in the Quetelet formula.

Many other doctors offered their BMI calculation:

  • BMI according to Brokk. From height in cm, you need to subtract 110, multiply the resulting number by 1.15.

For example, we can take a woman already familiar to us with parameters of 176 cm and 66 kg: (176 - 110) × 1.15 = 75.9. It turns out that according to Brokk, our woman has a lack of weight.

  • BMI according to Lorenz. Subtract 100 from height in cm. Then subtract 150 from height in cm and divide by 2. After that, subtract the second from the first result.

Difficult? Let's explain using the example of the already mentioned woman: (176 - 100) - (176 - 150) / 2 = 63. That is, according to Lorenz, our friend has three extra pounds.

Let's try to demonstrate on the example of our old friend. First, let's determine her height in inches: 176 / 2.54 = 69.3. Now we calculate BMI: 45.5 + 2.3 × (69.3 - 60) = 66.89.

  • BMI according to Humvee. The calculation formula is almost the same as the previous one: 45.5 + 2.2 × (height in inches - 60).

According to this formula, the optimal weight for our woman will be 45.5 + 2.2 × (69.3 - 60) = 65.96. As you can see, there is a difference, but very small.

  • BMI according to Kref. This technique allows you to calculate the body mass index by age and body type. To calculate BMI, you need to take several steps:
  1. Age must be divided by 10.
  2. You need to subtract 100 from height.
  3. Add up the results and multiply the resulting figure by 0.9.
  4. What happened, multiply by the coefficient of measurements of the wrist.

The coefficients, depending on the circumference, are as follows:

  • less than 15 cm - 0.9;
  • up to 17 cm - 1;
  • more than 17 - 1.1.

Let's explain with an example. Let's say the woman we talked about above is 40 years old, wrist circumference is 16 cm. Then her ideal weight will be: (176 - 100 + (40 / 10)) × 0.9 × 1 = 72 kg.

  • BMI according to Egorov-Levitsky. The authors of the book "Obesity", Professor Egorov and Doctor of Medical Sciences Levitsky, suggest not to calculate anything, but to check your weight according to the table they developed.
Height in cm Men Women
Asthenics Normostenics Hypersthenics Asthenics Normostenics
148 42,0 - 44,8 43,8 - 48,9
150 42,7 - 45,9 44,5 - 50,0
152 43,4 - 47,0 45,6 - 51,0
154 44,4 - 48,0 46,7 - 52,1
156 45,4 - 49,1 47,7 - 53,2
158 51,1 - 54,7 53,8 - 58,9 57,4 - 64,2 46,5 - 50,2 48,8 - 54,3
160 52,2 - 55,8 54,9 - 60,3 58,5 - 65,3 47,6 - 51,3 49,9 - 55,3
162 53,2 - 56,9 55,9 - 61,9 59,6 - 66,7 48,7 - 52,3 51,0 - 56,8
164 54,3 - 57,9 57,0 - 62,5 60,7 - 68,8 49,8 - 53,4 52,0 - 58,2
166 55,4 - 59,2 58,1 - 63,7 61,7 - 69,6 50,8 - 54,6 53,3 - 59,8
168 56,5 - 60,6 59,2 - 65,1 62,9 - 71,1 52,0 - 56,0 54,7 - 61,5
170 57,9 - 62,0 60,7 - 66,7 64,3 - 72,9 53,4 - 57,9 56,1 - 62,9
172 59,4 - 63,4 62,1 - 68,3 66,0 - 74,7 54,8 - 58,9 57,5 - 64,3
174 60,8 - 64,9 63,5 - 69,9 67,6 - 76,2 56,3 - 60,3 59,0 - 65,8
176 62,6 - 66,4 64,9 - 71,3 69,0 - 77,6 57,7 - 61,9 60,4 - 67,2
178 63,6 - 68,2 66,5 - 72,8 70,4 - 79,1 59,1 - 63,6 61,8 - 68,6
180 65,1 - 69,6 67,8 - 74,7 71,9 - 80,9 60,5 - 65,1 63,3 - 70,1
182 66,5 - 71,0 69,2 - 76,3 73,6 - 82,7 62,0 - 66,5 64,7 - 71,5
184 67,9 - 72,5 70,7 - 78,1 75,2 - 84,5 63,4 - 67,9 66,1 - 72,7
186 69,4 - 74,0 72,1 - 79,0 76,7 - 86,2
188 70,8 - 75,8 73,5 - 81,7 78,5 - 88,0
190 72,2 - 77,2 75,3 - 83,5 80,3 - 89,8
194 75,1 - 80,1 78,9 - 87,0 83,2 - 93,4

Body mass index (BMI)- a generally accepted indicator of the ratio of weight and height of a person - was first proposed by the Belgian mathematician Adolphe Quetelet in the middle of the 19th century. It is not difficult to calculate the body mass index - below you will find a simple formula for calculating BMI based on age. In our time, a close relationship has been revealed between the BMI indicator and a number of dangerous diseases (among which the most common are elevated blood cholesterol levels, heart attack, stroke, some cancers, lipid metabolism disorders, obesity). Depending on this or that degree of obesity (using the BMI indicator, which can be calculated and the degree of obesity can be determined from the table), it is necessary to choose the appropriate diet program or undergo a course of treatment after consulting a nutritionist.

Let's take a closer look at what other risk factors, in addition to the presence of one degree or another of obesity, can pose a danger to your health:
Hypertension (high blood pressure); reduced cholesterol (Lipoprotein Low Density high density lipoprotein); elevated cholesterol levels; elevated levels of neutral fats (triglycerides) in the blood, which is a direct consequence of obesity or very low physical activity.

The factors listed below are not directly related to BMI, but can indirectly affect the development of certain diseases. It should also be taken into account that the constitution of the body is due to heredity and cannot be adjusted:

Waist circumference 102 cm or more (for men)
Waist circumference 89 cm or more (for women)
Heart disease in one or more close relatives.

It is especially useful to know the body mass index for women. Thanks to the calculated BMI, you can adjust your chosen diet for weight loss and identify the problem of excess weight in time.
It should also be taken into account that even a slight weight loss (5-10%, if 1 or 2 degrees of obesity are detected) can significantly reduce the risk of developing diseases associated with overweight.

If your body mass index range is between 25kg/m2 - 29.9kg/m2, it is advisable to consult a nutritionist. It is possible that you will be advised to maintain your current weight (body constitution plays a key role here). However, we can safely say that in order to prevent weight gain and to reduce the likelihood of developing the above diseases, it is useful to lead an active lifestyle and observe moderation in food.
Below you can calculate the body mass index using the formula and see the table "Degrees of obesity"

For example, the BMI for a girl who is 165 cm (1.65 m) tall and weighs 52 kg would be 19.1.

1.65² = 2.7225

52: 2.7225 = 19.1

MASS DEFICIENCY <18,50
Severe underweight<16,00
Underweight 16.00 - 18.49

NORM
18,50 - 24,99
Overweight >25.00
Preobesity 25.00 - 29.99

OBESITY >30,00
Obesity of the first degree 30.00 - 34.99
Obesity of the second degree 35.00 - 39.99
Obesity of the third degree >40.00

By the way, calculate your ideal body weight is also very easy: just multiply the square of your height in meters by the desired indicator within the norm. Let's say we take 19.7 as a guideline. Then, with a height of 165 cm, your weight should be 54 kg (1.65²x21≈54 kg).

As we age, our metabolism slows down and some other changes occur that affect BMI. Body mass index adjusted slightly for age.

Everything is very simple here: for the age of up to 24 years, the BMI norm is within 19-24, and then for every next ten years of life, the upper limit of the norm rises by one - up to 25 for the age of 25-34, to 26 for the age of 35-44 year, etc.

AGE| ACCEPTABLE BMI|
19 - 24 19 - 24
25 - 34 20 - 25
35 - 44 21 - 26
45 - 54 22 - 27
55 - 64 23 - 28
over 65 24 - 29

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The body mass index calculator is an easy way that anyone can use to find out in a few seconds if their weight is within the normal range. Body mass index (BMI) is a coefficient that allows you to calculate a person's body weight in relation to his height online. It is very easy to calculate BMI, for this you need to apply only a simple formula. BMI does not measure body fat, but it does effectively indicate that a person is not at risk of being obese, overweight, or underweight. BMI for men is calculated in the same way as for women.

BMI formula

A simple formula for calculating BMI is given below:

BMI = body weight (kg) / height (m)2

How to calculate BMI? - it is enough to divide a person's weight in kilograms by his squared height in meters, for example: if a person has a height of 165 cm, then it must be multiplied by 1.65 x 1.65 = 2.7225.
Then the weight of a person, for example, 60 kg, is divided by the result: 60 / 2.7225.

So you get a BMI = 22.03.

Moreover, age does not matter in the calculation. Online you can calculate the body mass index for both women and men.

Interpretation of BMI results

In the International Classification of BMI for adults, calculations are indicated by which you can determine the norm or deviation from it. If BMI:

  • below 16.0 - a person has malnutrition;
  • 16.0-17.0 - exhaustion of the body (often due to a serious illness);
  • 17-18.5 - low weight;
  • 18.5-25.0 - normal value;
  • 25.0-30.0 - overweight;
  • 30.0-35.0 - 1 degree of obesity;
  • 35.0-40.0 - 2nd degree of obesity;
  • above 40.0 - 3 degree of obesity.

Another way to check if you are in the weight norm is the waist circumference indicator. For women, a waist circumference in the range of 80-88 cm already indicates excess weight. Waist more than 88 cm, in turn, speaks of obesity. Men with a waist circumference of more than 94 cm are overweight, we can talk about the initial degree of obesity when a man is the owner of a waist with a circumference of 102 cm. Obese people are most often prone to the following ailments: stroke, heart attack, arterial hypertension, certain types of cancer, diseases musculoskeletal system.

The calculation of BMI in children is carried out in the same way as in adults, only the data obtained are compared with the average results of this age group. Instead of defining intervals that indicate obesity, overweight and underweight, BMI in children allows comparison of the results of the coefficients of a certain sex and a certain age. Research in the UK shows, for example, that girls aged 12-16 have a much higher BMI than boys in the same age range.

Advantages and disadvantages of BMI

A huge advantage that BMI is characterized by is the fact that it is easy to calculate it using a formula. Studies show that a BMI of 18.5-25 is seen in people who enjoy long-term good health and have the least incidence of diet-related ailments such as type 2 diabetes or atherosclerosis. Thus, coefficients that deviate from the norm are a valuable evidence for a person that you need to take care of your health. But, unfortunately, a BMI within the normal range is not always a guarantee that you have a normal body weight. You may be at risk of latent obesity, which is most often diagnosed among people who are not physically active enough. More effective in this case will be the study of the percentage of adipose tissue in the body. Also, an elevated body mass index does not always indicate that you are overweight. It may happen that an above-normal BMI is the result of highly developed muscle mass with little fat content. For example, athletes have high BMI values, but they are in the right physical shape. After all, muscles are heavier than the same amount of adipose tissue. Physically active people should focus more on measuring their body contours rather than monitoring BMI results.

When calculating the BMI of people with a height of less than 150 cm and more than 190 cm, they will not get the correct result, in addition, this method is not suitable for monitoring body weight in pregnant women.

Scientists are thinking about introducing a classification of BMI indicators depending on geographical and cultural conditions.

Other methods for determining obesity

  1. Measurement of the thickness of skin folds (the degree of obesity depends on the thickness of the subcutaneous fat layer);
  2. measurement, which uses the method of bioelectrical impedance (passage of current through the human body with a very small force and voltage);
  3. measurement of body density by weighing it under water (the difference in density between fat and muscle tissue is used).

health warning

The resulting BMI calculations do not speak about the health or illness of a person, they indicate an increased risk of diseases associated with obesity.

The World Health Organization often uses body mass index to calculate the percentage of people who are obese or overweight. These calculations are especially important in Western countries, where obesity is the main disease of civilization. You already know how to calculate BMI. The result that you get may indicate that your body is susceptible to illness due to an improper diet. At the same time, this can be a good motivation for you to make changes in your diet and lifestyle.

BMI is used to assess the risk of various dangerous diseases: atherosclerosis, coronary heart disease, stroke, diseases of the musculoskeletal system, and even cancer. All of these diseases occur with obesity, which is why the BMI calculator is an important tool that allows you to quickly calculate a person's body mass index. Remember that the higher the degree of BMI, the greater the risk of various diseases.