A person’s BMI is calculated by taking their weight in kilograms and dividing it by their height in meters. There are four weight categories: underweight, normal, and overweight. BMI is a simple and inexpensive way to determine one’s weight.
A person’s body fat can be measured in other ways, such as waist circumference or hip circumference, however, BMI can not do so. Furthermore, these more direct measurements of body fatness appear to be as closely associated with important metabolic and illness outcomes as BMI.
What is the BMI formula?
The body mass index (BMI) is a calculation that compares a person’s weight to their height. It provides an economical and straightforward technique of categorizing people based on their BMI value, allowing us to screen people’s weight categories and predict their risk of developing health problems.
1. Metric units: BMI = weight (kg) ÷ height2 (meters)
Calculation process: The BMI is a straightforward calculation based on a person’s height and weight. BMI = kg/m2, where kg represents a person’s weight in kilograms and m2 represents their height in meters squared.
2. US units: BMI = (weight (lb) ÷ height2) * 703 (inches)
Calculation process: Multiply your height in inches by your height in inches to get your BMI. Then divide that figure by your weight. Then multiply that number by 705.
BMI weight categories
You will be placed in one of the following weight groups based on your height and weight:
- Underweight – BMI less than 18.5
- Normal healthy weight – BMI between 18.5 and 24.9
- Overweight – BMI between 25.0 and 29.9
- Obese – BMI between 30.0 and 39.9
- Morbidly obese – BMI 40.0 and above
Weight categories might be divided further. The table below, courtesy of the World Health Organization, depicts the international classification of adults as underweight, overweight, and obese based on BMI.
|Principal cut-off points||Additional cut-off points|
|Moderate thinness||16.00 – 16.99||16.00 – 16.99|
|Mild thinness||17.00 – 18.49||17.00 – 18.49|
|Normal range||18.50 – 24.99||18.50 – 22.99|
|23.00 – 24.99|
|Pre-obese||25.00 – 29.99||25.00 – 27.49|
|27.50 – 29.99|
|Obese class I||30.00 – 34.99||30.00 – 32.49|
|32.50 – 34.99|
|Obese class II||35.00 – 39.99||35.00 – 37.49|
|37.50 – 39.99|
|Obese class III||≥40.00||≥40.00|
IDEAL BMI CHART FOR CHILD AND TEEN (AGE 2-20)
The BMI calculator for children and adolescents ages 2 to 20 takes into account age, gender, height, and weight.
Adults who were obese as children are more likely to become obese as adults as a result of their obesity as children.
IDEAL BMI CHART FOR ADULTS & SENIORS
How to Use BMI Calculators
The BMI is a measurement of your body fatness and health. The higher your BMI, the more likely you are to have a high body fat percentage, and excess body fat is connected to both current and future morbidity. It’s fantastic news if your BMI suggests that you’re at a healthy weight. You should maintain track of your BMI on a regular basis to ensure that you remain in this bracket.
If your BMI is high and you are overweight or obese, you should make an appointment with your doctor, who may suggest additional diagnostic testing to rule out any health problems. Skinfold thickness and waist measurements, diet and physical activity evaluations, family history, and other appropriate health screenings are examples of diagnostic testing. Your doctor may also recommend changes to your lifestyle and food to help you lower your BMI.
If you have a low BMI and are considered underweight, you should consider changing your diet in order to gain weight. Your physician will be able to assist you.
Although there is a link between BMI and body fatness, BMI has limits that have been extensively debated in the medical community. These consist of
- Athletes and bodybuilders with a high muscle-to-fat ratio (muscle weighs more than fat) are classified as having a high BMI.
- There are variances in height and weight ratios between races.
- Age and gender are not taken into consideration. Women with the same BMI have more body fat than males with the same BMI, and older persons have more body fat than younger people with the same BMI.
- Pregnant or breastfeeding women, as well as adolescents and teenagers who are still growing and not physically mature, are not taken into account by BMI.