Formulas for determining the optimal ratio of weight and height

The weight calculator will help you calculate your ideal body weight and acceptable weight range for healthy people.

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 influences your 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 build. And the norm for thin people is 3-5% less. Therefore, it is not necessary to strive specifically for the ideal weight that the weight calculator . It is quite enough if your weight falls within the calculated range.

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

Body Mass Index (BMI)

One of the parameters that allows us to estimate a person’s weight and its correspondence to height is the body mass index. By the value of this value you can judge whether you are underweight or overweight
. Since excess weight directly affects human health, in particular the functioning of the heart, controlling your body weight is especially important. The online calculator we created allows you to accurately and quickly find out your body mass index. To do this, just indicate your height, weight and age, and in the case of children, also gender. As a result, you will receive complete and comprehensive data about your BMI.

The body mass index was developed in 1869 by statistician and sociologist Adolphe Quetelet. In Western countries and the United States, it has become increasingly popular and widespread due to the increased problem of overweight and obesity. When the need arose to quantitatively determine a person’s normal weight, they decided to use BMI, since the formula for calculating it is very simple.

The BMI parameter only indirectly allows one to judge the presence of excess weight or, conversely, its deficiency. But if the calculation results go beyond normal values, this is a reason to pay attention to your physical condition.

How to use the calculator

An online body mass index calculator will make the task much easier. But in order for the resulting value to be as correct as possible, you need to know your exact weight and height. Use the following tips to measure them correctly.

You need to weigh yourself in the morning and strictly on an empty stomach.

To measure weight:

1. Place the scale on a flat surface. It is advisable that they always stand in one place.
2. Always weigh yourself in the morning. At this time, the value seen will be as accurate as possible.
3. Before you step on the scale, be sure to go to the toilet.
4. Weigh yourself in the same clothes without shoes.

To measure your height yourself:

1. To begin, take a small box in one hand, a pencil and a small mirror in the other. Or find a place against the wall opposite the mirror.
2. Take off your shoes. Even slippers with thin soles can seriously distort the result, so take off your shoes.
3. Remove your headdress and all hair accessories. Comb your hair so that it lies flat.
4. Find an area next to a wall with a flat floor. It is best if the floor is tiled. Stand close to the wall, pressing your spine against it. Bring your legs together and press them firmly to the floor.
5. Straighten up as much as possible. Make sure your head, shoulders, buttocks and heels are in contact with the wall. Look forward and lift your chin. This will help straighten your body.
6. Lift the box, place it on your head and press it firmly against the wall. Use a mirror to check that the box is level. If it is even slightly skewed, the measurements will be inaccurate.
7. Use a pencil to mark the level at which your head is located. To do this, mark on the wall the place where the bottom of the box is located.
8. All you have to do is measure the distance from the floor to the mark using a measuring tape.

You can measure your height yourself using a box or book.

After you have taken all the measurements, you will need to enter them into the fields of the online calculator. In the “weight” field, enter your body weight in kilograms, and in the “height” field, enter your height in centimeters. Click the "calculate" button.

Please remember that the value obtained is for reference only and cannot replace specialist advice.

Body mass index in women

Women's body mass index is slightly lower than men's. A normal BMI for women can be considered to be between 19 and 27.

Normal body mass index for women from 19 to 27

At the same time, body mass index also depends on age (but we remind you that the formula does not take it into account). Below is a table showing normal BMI values ​​for women of different ages:

Body weight

Weight is the force exerted by the body on a support or suspension. Weight is measured, like any other force, in Newtons.

“But wait! Weight is measured in kilograms - I weigh 50.”

This is not entirely true. In everyday life, we often replace the concept of “mass” with the concept of “weight” and say: the weight of a suitcase is ten kilograms. In physics, these are two completely different concepts, which are interconnected.

If you have a scale nearby, we invite you to experiment! One caveat: our idea will work with mechanical scales, but not with electronic ones. Go!

Step 1. If you stand on the scales straight and do not move, your weight will be calculated according to the formula:

Two objections may arise here:

1. It's gravity, not weight. The formula is the same!
2. On the scales the mass is displayed in kilograms. And if I multiply my mass by the acceleration of gravity, I will clearly get a number almost 10 times greater than what the scales show.

Point of application of force. This formula is indeed similar to gravity. The weight of a body at rest is numerically equal to the mass of the body; the difference is only in the point of application of force.

Gravity is the force with which the Earth acts on the body, and weight is the force with which the body acts on the support. This means that they will have different points of application: gravity to the center of mass of the body, and weight to the support.

Scales measure strength. Scales work in such a way that they measure the weight of the body - the force with which we act on them, and show - mass. We can conclude that the scale is a dynamometer (a device that measures force).

Let's continue the experiment.

Step 2. Now let's play around and stand up on our tiptoes! The arrow deviated sharply to the left, and then returned to its place. You have given yourself an upward acceleration, while the free fall acceleration is always directed toward the center of the Earth (downward).

Now we calculate body weight using the formula:

Step 3. The last part of the experiment is to drop sharply onto your heels. Now you're pushing harder on the scale because you've added downward acceleration. The scale arrow will deviate to the right and return to its place when you come to a state of rest.

The weight formula will take the form:

By the way, if you stand straight on the scales, but weigh yourself in the elevator, everything will work the other way around. If the elevator goes up, then it seems to press the scales on the person standing on them, and this is exactly the situation with increasing weight. And if it’s down, the scales seem to “run away” from you to show a lower value.

We can describe this case through Newton's 2nd law . Let's take an elevator that goes down. Let us denote the forces in the figure.

N – ground reaction force [N];

mg – gravity [N];

a is the acceleration with which the elevator moves [m/s2].

N + mg = ma

When projecting onto the downward y-axis, we get:

−N + mg = ma

And now we need Newton’s third law - according to it, the support reaction force is equal to the weight of the body:

P=N

−P + mg = ma

P = m (g − a)

Try preparation courses for the Unified State Exam in physics with an experienced teacher at the Skysmart online school!

Body mass index in men

In men, the effect of age on the value of body mass index is not so significant. Physiologists distinguish only two age periods - from 18 to 30 years and after 30 years. The normal BMI for these groups is slightly different.

Normal body mass index for men is 21 to 26

In this case, the normal values ​​​​by age look like this:

About the interpretation of the result

After you do the calculations, check the tables. In addition to the standard BMI categories, below are decoding options for women and men, as well as taking into account age groups. This information can be used when creating a weight loss program.

BMI categories

Decoding for women

Decoding for men

Interpretation of BMI taking into account age

Please note that ages under 18 are not included in the table. This is because BMI is not considered a suitable assessment method for children and adolescents. In their case, determining the state of fitness and health is done using other tests.

If you find your result in the obesity column, be sure to contact a competent nutritionist. Only he can choose the right diet and exercise for you. Losing weight without the supervision of a specialist can be unsafe.

It is absolutely not necessary to calculate your body mass index yourself. Our convenient online calculator will do all the work for you.

Practical use

Body mass index is widely used in therapeutic and pediatric practice to monitor excess parameters. The goal is to prevent cardiovascular diseases, dysfunction of the metabolic system, and the development of type 2 diabetes in children and adults.

The practical application of Quetelet's formula does not require extensive data collection, which is provided for by the classical anthropological system: measuring body parameters taking into account race, gender, age and other specific characteristics. The calculation is methodically simple, highly informative and reliable in estimating the amount of fat. According to approved WHO standards, it is possible to make diagnoses of anorexia or obesity based on the index.

But the use of a special formula is not limited to healthcare. In the 1950s and 60s, the index was used by insurance companies in America and Europe to assess morbidity or mortality rates. The results were the basis for developing appropriate requirements for clients. Since then the standards have been re-evaluated. But the precedent has become an example for many sectors of the economy and the entertainment industry. For example, in France in 2015, an amendment was adopted to the bill on the modernization of the healthcare system, according to which it is prohibited to work as models for men and women with calculation results of less than 18 kg.

In everyday life, the indicator is used to independently diagnose overweight or underweight in order to take timely measures to maintain healthy forms.

Prediction accuracy based on BMI

And although the index is often used in medicine, more and more information is emerging about its inaccuracy. Several facts can be cited that cast doubt on the choice of the formula as the best tool for determining excess weight.

1. BMI does not determine the actual percentage of muscle and fat.

The disadvantage of the formula, as well as its advantages, is its simplicity. As a result, the BMI of a muscular athlete may coincide with that of an obese, untrained person. With the same height and weight, the percentage of fat, appearance and, accordingly, health risks can vary significantly. Studies of hundreds of people showed that athletes often showed an index of excess weight, and women with clearly extra pounds were within the normal range.

Another study of 13 thousand people showed similar information. Using bioimpedance analysis, scientists compared BMI with actual body fat percentage. The index showed obesity in 21% of men and 31% of women, while a more accurate scientific analysis showed 50% of men and 60% of women. We can say that in approximately every second case, the body mass index gives incorrect information, reassuring an overweight person.

2. BMI does not take into account gender and age

In order to conduct large-scale research, the scope of the index was deliberately made universal. But the volume of fat in men and women differs by about 10%. Is it right to apply the same criteria to different genders?

Age changes the proportions of muscle and fat tissue in the body. Over time, metabolism slows down, muscle tissue begins to break down, and fat tissue begins to accumulate. Correct conclusions require taking into account both the person’s gender and age. According to statistics, BMI in men is higher than in women.

3. BMI does not take into account the three-dimensionality of a person.

Oxford professor Nick Trefenthen also doubted the ability of the BMI formula. According to the scientist, it does not take into account the real structural features of the human body. In it, height and weight change nonlinearly. As a result, the formula considers short people to be slimmer and tall people to be denser. Trefenthen adjusted the formula so that it gave correct results:

BMI = 1.3 × weight / height 2.5,

where body weight is measured in kilograms and height in meters.

Nevertheless, the creator of the formula himself considers it imperfect, like any other formula in general - the human body has too complex a structure and shape.

4. Change in BMI norm

Over the past 30 years, the “normal” body mass index has changed several times. If before 1998 in America the threshold value was 27.8 kg/m2, then after 1998 doctors began to consider 25 kg/m2 as such. A small change in the standard resulted in 29 million Americans being considered overweight.

How to determine your ideal weight

Disputes among scientists on this issue have not stopped for many decades. The answer has not yet been found.

There is a very simple standard formula for calculating your weight norm: Subtract 100 from your height.

Many specialized experts will call this result (in kilograms) your individual norm.

The technique does not take into account the age and proportions of the skeleton, and this reduces the accuracy of the calculation. After all, there are many different types of proportions - thin-boned (asthenics), standard, large-boned (hypersthenics).

To compensate for the lack of simple calculation, the French physician and anthropologist in the nineteenth century introduced the so-called Paul Broca formula (under his own name). He proposed an indexing system that took into account racial differences in body and skeletal structure. These are several separate formulas for determining your ideal weight. One of them is still popular among many specialists.

The ideal value is calculated as follows:

1. For people shorter than 1.65 m, division by 100 is used.
2. From 1.65 to 1.75 m – 105.
3. From 1.75 m and above – 110.

Since the proposed method does not take into account age and structural features of the skeleton, it needs amendments.

People under thirty years of age should reduce the result by seven to ten percent. Age fifty years and older – an increase of five to seven percent. For hypersthenics – an increase of ten percent. For asthenics - deduct the same number.

Note. Calculations of normal body weight are relevant only for those who have reached the age of twenty-one. For children, adolescents and young men, it is not possible to determine the ideal weight for a number of reasons associated with significant fluctuations in all parameters taken into account.

Body mass index for men and women by age makes it possible to detect, with the best possible accuracy, a tendency to a specific type of disease.

If, for example, your body weight exceeds the norm by fifteen percent, this is an alarming signal. It should be given serious attention. The time has come to thoroughly change your diet and diet, increase physical and sports activity, and consult with medical specialists about additional measures.

Exceeding the norm by thirty percent means you need a complete change in your worldview, life activity and eating behavior.

For each time cycle of life, only its own individual food preferences are permissible. Nutrition should be appropriate for your age, weight and build. To avoid common mistakes when compiling a list of necessary products, seek help from a nutritionist. This is especially important for women in general and for women over forty in particular. They are more likely to be obese than men. It is also more difficult for them to control their weight.