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Calorie Calculator, BMI Calculator, Ideal Weight Calculator

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Body mass index (BMI)

The body mass index is used as an international unit to measure the weight to height ratio.

The body mass index is not suitable for calculating your weight during pregnancy, for professional athletes and children under 20 years of age. Body weight is considered normal if the BMI is between 18 and 25, preferably between 20 and 25.

BMI value





Underweight (very thin)

16,0 – 16,9

Underweight (moderately thin)


Official indicator of mental anorexia

17,0 – 18,4


18,5 – 24,9

Normal weight

25,0 – 29,9

Overweight (not considered a disease)

30,0 – 34,9

First degree obesity

35,0 – 39,9

Second degree obesity

≥ 40.0

Third degree obesity - extreme or very severe obesity


Basic metabolism

Basal Metabolic Rate (BMR) is the amount of energy your body spends at rest in a neutral and moderate environment (the digestive system is inactive - after about 12 hours of fasting).


Ideal weight

Ideal body weight (IBW) is a clinical standard that includes biometric variables like height, sex and age. It is used to determine the correct dosage of prescribed medication for patients and in sports to determine body weight. Although the IBW formula is widely used in clinical settings, it is not a universal criterion for measuring the percentage of body fat and muscle mass, as this varies from individual to individual.

BMI or Body Mass Index

BMI - body mass index - or Quetelet index (indice de Quetelet) is a method invented by Belgian statistician Adolphe Quetelet (1796-1874) to calculate the degree of obesity in the human body. The body mass index indicates whether a person's body weight is healthy in relation to their height.

To calculate BMI, divide weight (in kilograms) by height squared (in meters).

The World Health Organisation (WHO) recommends a healthy BMI range for both men and women between 18.5 and 25. It is widely used in the medical field as a quick indicator of possible health complications. In general - the higher the BMI, the more likely a person is to suffer from health problems such as obesity, diabetes, heart disease and many others. Doctors use BMI to inform their patients about possible health problems, especially if there is a noticeable gradual increase in their BMI, and it is currently the official indicator to classify individuals according to different levels of obesity.

BMI ranges vary depending on factors such as region and age and are sometimes sub-categorised as extremely underweight or severely obese. Being overweight or underweight can have a significant impact on health, so although BMI is not a completely accurate method of calculating a healthy body weight (as it does not take into account the relationship between muscle and fat mass) - it is widely used in initial healthy weight diagnosis as it is quick and accurate enough for 90-95% of people.


What to consider when interpreting the calculated BMI

Although BMI (body mass index) is a widely used and helpful indicator of a healthy body weight, it has its limitations. It is important to remember that BMI is only a calculation that ignores body composition. As body types, muscle and bone mass and fat distribution vary from person to person, BMI should be used in conjunction with other measurements and not as the sole method of determining a person's healthy body weight.


BMI differences in adults

BMI cannot be completely accurate as it is a measure of excess body weight, not excess body fat. BMI is also influenced by factors such as - age, gender, ethnicity, muscle and body fat mass and physical activity level. For example, an older person may have a BMI within a healthy weight range, but if they are completely inactive in their daily life, they may have a significant amount of body fat.

On the other hand, a young person with a significant muscle mass may have a BMI that indicates an unhealthy weight.

Athletes and people who are physically active (have more muscle mass than the average person) may have a BMI in the overweight range because muscle is heavier than fat.

In most cases:

  • Older adults tend to have more body fat than younger people with the same BMI.
  • Women tend to have more body fat than men of equal BMI.
  • Muscled individuals and trained athletes may have higher BMI due to higher muscle mass.

BMI differences in children and adolescents

The same BMI limiting factors apply to children and adolescents as to adults. In addition, children's height and level of sexual maturation can also affect BMI and body fat. BMI as an indicator of excess body fat is better for obese children than for overweight children whose BMI could be affected by increased body fat or fat-free mass (all body components except fat, which includes water, organs, muscles, etc.). In thin children, the difference in BMI may also be related to fat-free mass.


Classification of BMI results in children (2-20 years)

The weight calculator is designed to determine BMI for adults. For children (up to 20 years - while the body is growing), the calculation of body mass index is identical but with a more detailed classification scale (gender and age are taken into account, and BMI is also calculated by month. Children's BMI is calculated by comparing data with other children of the same age in percentiles).

Body mass index age precentiles for boys aged 2 to 20 years

Body mass index age precentiles for 2 to 20 year old girls


Basic metabolism

The dietsabc.com calculator to calculate the basal metabolic rate (BMR) uses the Harris-Benedict equation.

The Harris-Benedict equation was one of the first used to calculate the basal metabolic rate (BMR) - the amount of energy the human body uses at rest in a day. The formula was updated in 1984 and was used as practically the only method of calculation until 1990 when the Mifflin-St Jeor equation was introduced.

The Katch-McArdle formula differs slightly in that it calculates energy expenditure at the state of leisure, not at rest, and takes into account fat-free body mass, which is not taken into account in either the Mifflin-Stgeor or Harris-Benedict equation. The Mifflin-St. George equation is considered the most accurate for BMR calculation, while the Katch-McArdle formula may be more precise for skinny people who know their body fat percentage.


Mifflin-St Jeor equation

For men: BMR = 10 W + 6.25 H - 5A + 5

For women: BMR = 10 W + 6.25 H - 5A - 161


The revised Harris-Benedict equation

For men: BMR = 13.397 W + 4.799 H - 5.677 A + 88.362

For women: BMR = 9.247 W + 3.098 H - 4.330 A + 447.593


Katch-McArdle equation

BMR = 370 + 21.6 (1 - F) W



W i- the body weight in kg

H - the height of the body in cm

A - age

F - the percentage of body fat


Ideal weight

Several formulas have been developed to determine the ideal weight, and depending on which formula is used in the calculations, the ideal weight for the same person can vary by up to 10 kg. The dietsabc.com calculator uses a formula published by G.J. Hamwi in 1964, which was originally used to calculate the dosage of medication needed for a given person.


What is your ideal weight?

Most of us have tried to lose weight at some point, some have succeeded, but others have not. The ideal weight can be defined in different ways - for some, it is the weight at which they feel best physically, and for others - the weight at which they feel best emotionally.

Currently, the ideal body weight is based on visual appeal created by the media, i.e. the ideal of beauty is variable, for example - a few hundred years ago it was round pale aristocrats compared to skinny and tanned peasant women -😊.

The concept of ideal body weight (IBW) was introduced to determine the doses of medication needed for a given person, and the formulas that calculate it are not linked to how a person looks or feels physically and emotionally at a given weight (doses are based on IBW, not total body weight). Today, IBW is also widely used outside medicine, for example, in sports where athletes are classified according to their body weight (weight class).

It should be noted that IBW is not an ideal figure because it does not take into account the percentage of fat and muscle in the human body. This means the body weight for athletes and physically active people is higher than the calculated ideal weight. Remember that the calculated ideal weight is not necessarily an indicator of health or the weight a person should aim for. It is possible that your weight could be higher or lower than the calculated weight, and you are perfectly healthy.

It is not known exactly what weight each individual should have. It largely depends on the person himself. So far, there is no single indicator, neither IBW - ideal body weight, BMI - body mass index, nor any other that can determine precisely how much a person should weigh to be healthy. All these methods are great for initial diagnosis, but if they indicate an unhealthy body weight, you should see a doctor before choosing a diet.

To maintain health, it is more important to follow the basic principles of a healthy lifestyle and proper nutrition, than to aim for a certain weight according to a generalised formula. For example, regular physical activity, eating fresh rather than processed foods, getting enough sleep, etc. can help you maintain a healthy weight.


The main factors influencing the ideal weight


In theory, age should not have a significant effect on IBW in girls after 14-15 years of age and in boys after 16-17 years of age, when most people stop growing. It is important to remember that male and female height decreases by 3.8-5 cm by the age of 70 and as people age, muscle mass decreases and excess body fat accumulates more easily. This is a natural process, but it can be slowed down, for example, with a healthy diet, exercise and enough sleep.


Women generally weigh less than men, although they naturally have a higher percentage of body fat. This is because a man's body usually has more muscle mass, and muscle is heavier than fat. Women also tend to have lower bone density and are smaller in stature compared to men.


The taller a person is, the more muscle and body fat they have, which results in higher weight. If a man and a woman are the same height, the man should be about 10-20% heavier.

Body type

Body type (skeletal bone size) is another factor that can influence the ideal weight (within a range of a few kilograms). It is usually classified as small, medium or large (fine bones, medium bones, wide bones). It is measured on the basis of the circumference of the person's wrist in relation to their height. You can find out how to measure the wrist circumference correctly HERE The classification is as follows:

For women less than 158.5 cm tall
  • Fine bones = wrist size less than 12.7 cm.
  • Medium bones = wrist size from 12.7 cm to 14.6 cm.
  • Wide bones = wrist size greater than 14.6 cm.
For women whose height ranges from 158.5 to 167.6 cm
  • Fine bones = wrist size less than 15.2 cm.
  • Medium bones = wrist size from 15.2 cm to 15.9 cm.
  • Wide bones = wrist size over 15.9 cm.
For women over 167.6 cm tall
  • Fine bones = wrist size less than 15.9 cm.
  • Medium bones = wrist size from 15.9 cm to 16.51 cm.
  • Wide bones = wrist size greater than 16.51 cm.
For men whose height is over 167.6 cm
  • Fine bones = wrist size from 14 cm to 16.5 cm.
  • Medium bones = wrist size from 16.5 cm to 17.8 cm.
  • Wide bones = wrist size over 17.8 cm.

People with wide bones naturally weigh more than someone of the same height with fine bones - this is true for both the IBW and BMI calculations.


The most popular formulas for determining the ideal weight

The formulas differ in the values used based on the research and findings of the scientists involved in their development. The Devine formula is the most widely used formula for measuring IBW.

J. Hamwi formula (1964)

It was developed for drug dosing purposes.

For men: 48.0 kg + 2.7 kg per inch over 5 feet

For women: 45.5 kg + 2.2 kg per inch over 5 feet

J. Devina formula (1974)

Like the Hamwi formula, it was initially designed to calculate the dosage of a medicine based on a person's weight and height. Over time, it became the universal method for calculating IBW.

For men: 50.0 kg + 2.3 kg per inch over 5 feet

For women: 45.5 kg + 2.3 kg per inch over 5 feet

J.D. Robinson formula (1983)

Modification of the Devine formula.

For men: 52 kg + 1.9 kg per inch over 5 feet

For women: 49 kg + 1.7 kg per inch over 5 feet

R. Millera formula (1983)

Modification of the Devine formula.

For men: 56.2 kg + 1.41 kg per inch over 5 feet

For women: 53.1 kg + 1.36 kg per inch over 5 feet


Calorie calculator

Calorie counting is a widely accepted and highly effective method of weight management. Each food package shows precisely how many calories are in 100g of a particular product - this makes calorie counting relatively easy.


How many calories do you need?

People usually become interested in energy consumption and calorie counting when they want to lose weight because the easiest way to lose weight is to reduce the intake of calories each day.

But how many calories does the body need to be healthy and function normally? This greatly depends on age, weight, height, gender and level of physical activity - so it varies from person to person.

For example, a physically active 25-year-old 180 cm man needs significantly more calories than a 70-year-old 160 cm woman with a sedentary lifestyle. Adult men typically need 2000-3000 calories per day to maintain their weight, while adult women need around 1600-2400 calories.

The body doesn't need a lot of calories just to survive. However, taking in too few calories makes the body function poorly because energy (calories) is used only for vital functions that are essential for survival. Several studies have shown that women should consume at least 1200 calories and men at least 1500 calories per day.

It is usually a challenge for the novice to determine how many calories per day they need to maintain their weight, or to lose weight without harming their health, or to gain weight.

The dietabc.com calorie calculator calculates the calories needed by first calculating the Basal Metabolic Rate and then multiplying it by the physical activity factor (1.2-1.95).

For gradual weight loss, the calorie requirement is calculated using a 15% calorie deficit, and for rapid weight loss, a 30% calorie deficit. It is not recommended to reduce calorie intake by more than 30% per day, as losing weight too quickly is harmful to health and may have the opposite effect of slowing down metabolism in the near future - regaining the weight lost.

Svarīgi atcerēties, ka notievējot ir izšķiroša nozīme veselīgam un sabalansētam uzturam, jo, atņemot organismam nepieciešamās uzturvielas, var rasties gan veselības, gan skaistuma problēmas (āda, nagi, mati).



Official website of the US Centers for Disease Control and Prevention.



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