Calculate body mass index formula. BMI (body mass index) calculator online: how and why? Severe underweight

Body mass index(BMI) is a measure of a person's height and weight that is designed to determine whether a person is underweight, normal, or overweight. Being overweight is a problem because it can lead to other health problems. To calculate your individual body mass index, simply select your weight and height in the form below.

It is believed that for women the ideal BMI is from 20 to 22, and for men, as a rule, from 23 to 25. Statistics also say that people with an indicator from 18 to 22 live longer on average.

If your BMI is above 25, this is not good. However, you should not worry about this, first of all, be happy. Getting depressed due to imperfect body weight is not healthy!

It is also worth noting that this formula for calculating the Body Mass Index overestimates the obesity indicator for people of athletic build, since it does not take into account their muscle mass. It is also not suitable for children.

How to calculate Body Mass Index using a regular calculator?

1. Enter your weight into the calculator kilograms.
2. Twice divide the number by the height in meters.
3. The resulting number will be your Body Mass Index.

What is BMI used for?

Interest in determining the level of obesity grew simultaneously with the development of the problem of excess weight in Western countries.

Body mass index was developed more as a tool for public research than for personal use, and to use this indicator as a medical diagnosis, as sometimes happens, is not entirely correct.

At the same time, the ease of use of BMI explains such a high popularity of the calculator. An index in the range of 18.5 - 24.9 indicates optimal weight, below 18.5 is an indicator of underweight, and if it exceeds 30, then this indicates obesity, which carries a health risk.

It is recommended that already with a body mass index of 25, you should think about losing weight, especially if your waist size is large or other risk factors are present. various diseases(shown below). Even losing a small amount of body weight (eg 10%) can significantly reduce the risk of developing obesity-related diseases. If you are overweight, but your waist is not too wide, and there are less than 2 risk factors, then the main goal is not losing weight, but preventing further weight gain.

Waist circumference measurement

It is the waist circumference that is an excellent indicator for determining the degree of obesity. abdominal cavity which can lead to hypertension, cardiovascular diseases, type 2 diabetes and other complications.

Determining your waist circumference is quite easy - just place the measuring tape horizontally around your waist so that the tape fits snugly against it. For men, a waist of up to 102 cm is considered normal, and for women up to 88 cm - violation of this norm means a risk of developing various complications. It is especially high when a large waist circumference is combined with a high BMI, indicating overweight or one degree of obesity. In addition, there is a risk for those people who have normal index, but their waist circumference is higher than normal.

Other risk factors for developing diseases

In addition to a BMI above 25 and a large waist circumference, there are other risk factors for diseases. These include:

• High blood pressure(hypertension).
• High LDL cholesterol (also called “bad” cholesterol).
• Low level HDL cholesterol(“good” cholesterol).
• High triglyceride levels.
• High levels of glucose (sugar) in the blood.
• A family history of heart disease.
• Lack of physical activity.
• Smoking.

What can BMI tell you about your body?

Body mass index is not intended for diagnosis; rather, it acts as an average indicator. But if you want to try new diet or a fitness program, then our calculator will help determine the starting point. If you are overweight and have some flabby body, but the index is within the normal range, then you should focus, first of all, on exercise, and hold off on diet for now.

If the goal is to fit into old clothes and lose a few kilograms, then it is best to combine a diet and a set of exercises.

When BMI indicates obesity or a condition close to it, then you should stop looking for excuses and seriously engage in a diet and fitness program in order to protect your health.

What is body mass index and how to calculate it for women by age is a very popular topic, one might say hackneyed. Slimness today is actually synonymous with beauty and certainly an integral part of health. Insufficient weight, as well as excess weight, negatively affects the functioning 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 norm will be different for people of different genders, constitutions, and ages. The most accurate formula today is considered to be the one used to calculate body mass index. Still counting yours ideal weight according to the formula “growth minus 110”? This is correct, but not for everyone. After all, you don’t take into account many important indicators, for example, body type and age. Body mass index helps to calculate your ideal weight much more accurately. Let's figure out what it is.

What is body mass index (BMI)?

Body mass index is an indicator characterizing 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 condition of a person’s body - the presence of obesity or dystrophy and their degree. Calculating BMI is quite simple; it can be done at home. Perhaps it is the result of calculating BMI that will become your starting point on the path to normal body weight.

The first BMI formula appeared in the 19th century, its author was the Belgian Adolphe Quetelet. Subsequently, many scientists worked on 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 her BMI as follows: BMI = 50 * (1.65 * 1.65). The final BMI value is 18.36.

After this you receive a finished figure. As a rule, a weight between 19-25 is considered normal, but this is an average figure. It is not suitable for minors, elderly people or professional athletes. It turns out that just calculating the body mass index for a woman, even taking into account her age, is not enough to understand the state of her body. Indicators are deciphered 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 general idea about the state of the body.

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

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

Besides, appearance 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 defined muscles.

The interpretation of BMI will also depend on your body type, which is determined by measuring your wrist circumference. This is how thin-boned, normal-boned and broad-boned types are distinguished.

Men have more muscle than women, which means their 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 using separate tables.

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

The feeling of one’s own fullness or thinness is very subjective; some consider themselves fat, being more than slim, while others do not consider the 10-20 kg of fat hanging on their sides to be extra. The BMI calculation was created to help you understand how prone you are to obesity and how much your weight fits into the average norm.

In medicine, calculating BMI is used to adjust drug doses, 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 drive themselves to exhaustion with strict diets or complete refusal from eating because they feel they are not slim enough.

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

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

Lack of weight is also fraught with serious health problems - metabolic disorders, water-salt balance, hormonal imbalances, vitamin deficiency, amenorrhea, osteoporosis. Complications due to these diseases can even lead to death, so it is very important to be careful about 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 individual feature exactly your body. If you are full of energy, feel good and are satisfied with your health, you definitely shouldn’t reshape yourself for the sake of 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 aged about 20-40 years.

If you don't want to bother with squaring and dividing numbers, you can use a ready-made BMI table. The advantage of such tables is different variants for men and women, separate tables for athletes, pregnant women and women over 45 years of age.

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 obtained. For hypersthenics, on the contrary, the result should be increased by 10%. Accurate measurements of height and weight should be taken in the morning on an empty stomach after visiting the restroom.

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

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

We offer you a convenient BMI calculator, decoding taking into account age and normal indicators You will find the physique below, and instructions for using this application are also provided there.

Beauty and health are two main values ​​in our lives. The constant criterion of beauty is harmony.

How harmonious is your body? How consistent are your weight and height, age and body type? One of the most common indicators – body mass index (BMI) – will help you assess this.

Body mass index is a parameter that determines the correspondence between a person’s height and weight. Exceeding the norm indicates an excess of adipose tissue and warns of the danger of obesity, and a decrease also alarm signal: It speaks of both malnutrition (starvation) and digestive problems.

How to correctly calculate a person's body mass index

The formula for determining body mass index was proposed in 1869 by Adolphe Quetelet, a Belgian sociologist and statistician: BMI is equal to body weight M, measured in kilograms, divided by the square of height L, measured in meters:

BMI=M[kg]/L^2[m]

The resulting number falls within the range of 15-40, but the normal range for people 19-40 years old is 19-25, and after 40 - 19-30.

All these figures refer to people of normosthenic physique.

Finding out your body type is easy. You need to measure your wrist at the narrowest point: a normal value is 18-20 cm for men and 15-17 for women.

A narrower wrist is a sign of asthenic build, "thin bone", wider is inherent in the hypersthenic type, "broad bone".

The simplest way to determine this without measuring is by large and index fingers hands clasp your wrist.

If the fingers overlap each other - you are asthenic; if (almost) touching - you have a normal physique; if they do not reach each other significantly - you have a hypersthenic type.

Asthenics are usually tall, thin, they build muscle with difficulty, normosthenics are proportionally built and look harmonious, and hypersthenics are prone to being overweight and even obese.

Recommended settings for different types physiques can shift towards reduction (for asthenics) or increase (for hypersthenics). There are detailed tables of BMI indicators for different body types.

Online calculation using a calculator

Place the “weight” slider at the point corresponding to your current weight, and use the “height” slider to record your height. The third slider will install itself and show BMI.

Example: for a girl 27 years old, height 168 cm, weight 71 kg, the BMI is equal to 25.2 - which slightly outside the acceptable range.

If the resulting number does not fit into the norm, you weigh more or less than you need.

It is easy to calculate the recommended weight: fix the height slider and move the weight slider to the left (if the permissible weight is exceeded) until you get an index of 25; the resulting weight is the maximum allowable value for you.

Continuing to drag the slider to the left until the number 19 appears on the bottom line will give you the bottom border.

In our example, BMI will fall in the range of 19-25 if the weight is from 53.6 to 70.5 kg. Of course, there is such a wide range " norms" is difficult to consider as a guide to action, so below we will provide a more precise formula for determining " ideal mass«.

The following video will tell you how to calculate body mass index (BMI) without a calculator:

Interpretation of results

A high index indicates overweight, a low index indicates underweight. Both is a deviation from the norm.

The cause of insufficient weight may be starvation, complications after operations, significant physical exercise, as well as digestive problems. Overweight directly linked to obesity.

The World Health Organization (WHO) in 1997 adopted the following classification of diseases associated with BMI:

• less than 15- critical lack of weight, dystrophy;
• 15- 18,5 - weight below normal, increased risk diseases of the digestive tract;
• 18,5- 24,9 - norm;
• 25-29,9 - overweight;
• 30-34,9 — obesity I degrees;
• 35-39,9 — obesity of the second degree;
• more than 40 — obesity III degrees.

Excess adipose tissue can cause a variety of pathologies: heart disease, hypertension, joint diseases, .

Avoid overeating and listen to your body, remembering to undergo regular preventative medical examinations.

Normal values ​​for women and men

The BMI calculator is not applicable to children and adolescents under 18 years of age. For them, there are so-called centile tables, which present the average values ​​of height and weight at a given age. If the child’s parameters fit into these fairly broad frameworks, then there is nothing to worry about.

The method does not work for pregnant women either- but it’s unlikely that any of them will be very upset about this.

With age, a person’s weight usually increases, so the permissible BMI range also shifts.

For example, there is such a classification depending on age.

Age - BMI

• 19-24 — 19-24;
• 25-34 — 20-25;
• 35-44 — 21-26;
• 44-58 — 22-27;
• after 58 - 23-28.

However, for lean people, underestimated numbers are not a deviation, but only indicate limited applicability this method.

Disadvantages and Limitations

The above Quetelet formula does not take into account the different specific gravity of muscle and adipose tissue. Since muscles are heavier than fat, in people with highly developed muscles (athletes, bodybuilders) BMI may be increased with complete absence fat deposits.

The location of adipose tissue deposition, as well as the percentage of visceral (internal) fat, also plays a role. Most “bad” fat settles in the waist and abdomen.

Fitness centers have special devices that show the percentage of muscle and fat tissue, in particular, the amount of visceral fat.

In case of disruption of the coordinated functioning of the body Water may be the cause of increased weight(edema). BMI also increases.

The inapplicability of this method to assessing the condition of children and pregnant women has already been mentioned.

The dream of an ideal weight: what to compare with

And yet, is there a universal law for determining ideal proportions? The answer is negative: We are all different, and the canons of beauty change. However, there are a huge number of the most different rules calculations that make it possible to significantly narrow the spread obtained using the BMI method.

For example, the ideal body weight M according to the Devine method is determined as follows:

• for men: M = 50 + 2.3 * (0.394 * height – 60);
• for women: M = 45.5 + 2.3 * (0.394 * height – 60).

The coefficients in the Robinson formula are slightly different:

• for men: M = 52 + 1.9 * (0.394 * height – 60);
• for women: M = 49 + 1.7 * (0.394 * height – 60).

The girl from our example should ideally weigh from 59.5 to 63.7 kg - which falls in the middle of the interval proposed by the BMI method: 53-70.5 kg.

All these formulas, numbers, norms are only guidelines. But they help to correctly assess the situation and set tasks. Your beauty and health are completely in your hands!

What is the ideal body weight? You will learn about this from our video:

In contact with

Ideal weight is an average standard, which is calculated based on data on large quantities of people. But all people are different. Lifestyle, food culture, nationality and body type - all this influences the ideal weight. For example, normal weight people with a strong physique will be 2-3% higher than those with an average physique. 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 quite enough if your weight falls within the calculated range.

Besides 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 = M: P 2, where

M – body weight in kg

P – height in meters

Example of calculating 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 overweight bodies.

Interpretation table for BMI indicators

When strong deviation from the norm, it’s time to seriously think about correcting your weight. With reduced weight, dystrophy develops. In the modern civilized world, its cause is usually deliberate malnutrition. The desire to have is unnatural slim figure can result in both mental and mental disorders physical health- ability to work decreases, skin dries, hair falls out. All this comes from lack necessary for the body substances.

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 stones and gallbladder, joint deformities, impotence, myocardial infarction and many other diseases. The entire body works under overload, moving masses of fat in space that were not provided for by design human body. It is not surprising that the life expectancy of obese people is on average 6-8 years less than that of others.

Body mass index is a unique tool, invented two centuries ago, that is successfully used by people concerned about their health. It was then, in the 19th century, that medical theorists and practitioners noticed that the so-called “healthy” mass of a person is directly related to his height and real weight. Using a special table, you can easily determine whether you have a couple of extra pounds in your body and whether you are at risk of obesity. To do this, it is enough to know only the basic parameters of your body.

Your body mass index value

For example, the input data is: weight = 85 kg, height = 165 cm. Therefore, BMI = 85: (1.65 × 1.65) = 31.2.

After calculating your BMI, you need to compare your result with the table

Once you have found out your BMI, you need to refer to a table that will help you determine if you have excess fat in your body. The exception is professional weightlifting athletes who have increased muscle mass.
For them, the indicators, of course, should be somewhat higher.

Calculate BMI

If your body mass index is:

• 20-25 - no need to worry: you have a normal weight that is in harmony with the world;
• 25-30 - you should start taking care of your body; you are slightly overweight. Further accumulation of fat increases the risk of developing various diseases and deterioration general condition health;
• 30-35 - you have a clear tendency towards obesity, so you need to make every effort to reduce this figure;
• 35 or more - you are obese; It's time to sound the alarm and start actively working to restore its former form.

BMI table

Classification of health conditions depending on BMI	BMI		Health Risk	What to do
	18-25 years old	more than 25 years
Anorexia nervous. Anorexia ataroxic.	Weight less than 15% of expected, BMI less than 17.5		High	Weight gain is recommended to treat anorexia.
Underweight	Less than 18.5		Absent
Norm	19,5-22,9	20,0-25,9		no weight loss required
Excess weight	23,0-27,4	26,0-27,9	Elevated	Weight loss recommended
Obesity I degree	27,5-29,9	28,0-30,9	Elevated	Weight loss is recommended
Obesity II degree	30,0-34,9	31,0-35,9	High	Weight loss is strongly recommended
Obesity III degree	35,0-39,9	36,0-40,9	Very high	Weight loss is strongly recommended
Obesity IV degree	40.0 and above	41.0 and above	Extremely high	Immediate weight loss is necessary