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BMI Calculator

বিএমআই ক্যালকুলেটর

Find your body mass index from your height and weight, and the healthy weight range for your height.

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Height unit
Weight unit

For adults aged 18 and over.

Your BMI will appear here

Enter your height and weight, then select Calculate BMI.

How BMI is calculated

Body mass index (BMI) compares your weight with your height:

BMI = weight in kg ÷ (height in metres × height in metres)

If you enter feet and inches or pounds, they are converted exactly first: 1 inch is 2.54 cm and 1 pound is 0.45359237 kg.

Worked example

A person who is 170 cm (1.70 m) tall and weighs 70 kg: 1.70 × 1.70 = 2.89, and 70 ÷ 2.89 = 24.2. That is in the healthy weight range. At 170 cm, the healthy range is about 53.5 kg to 72.0 kg.

How to use the calculator

  1. Choose your height unit (cm, or feet and inches) and enter your height.
  2. Choose kg or lb and enter your weight.
  3. Select Calculate BMI. The result updates as you change the numbers.

Inches can be left empty if you are exactly a whole number of feet tall. The calculator accepts heights from 50 to 272 cm and weights from 2 to 650 kg; these limits only catch typing mistakes.

BMI categories for adults

This calculator uses the World Health Organization (WHO) adult categories. Your category is decided by the BMI shown on screen, rounded to one decimal place, so the number and the category always match.

  • Underweight: below 18.5
  • Healthy weight: 18.5 to 24.9
  • Overweight: 25 to 29.9
  • Obesity: 30 and above (class I: 30 to 34.9, class II: 35 to 39.9, class III: 40 and above)

The healthy weight range shown in your result is the weight that gives a BMI of 18.5 to 24.9 at your height.

What BMI can and can’t tell you

BMI is a screening measure, not a diagnosis. It is a quick way to see whether weight might be worth discussing with a health professional, but it does not measure body fat, where fat is carried, fitness or overall health.

  • The categories are for adults aged 18 and over, not children or teenagers.
  • BMI is not suitable during pregnancy.
  • Very muscular people can have a high BMI without having much body fat, and older adults can have a healthy-looking BMI with low muscle.

Background on Asian populations

A WHO expert consultation in 2004 noted that many Asian populations have a higher risk of some health problems at a lower BMI than the standard cut-offs suggest, and proposed additional public-health cut-off points of 23 and 27.5. This calculator keeps the standard WHO categories above. If you want to know what BMI means for you, ask a doctor.

Frequently asked questions

How is BMI calculated?

BMI is your weight in kilograms divided by your height in metres squared. For example, 70 kg at 1.70 m gives 70 ÷ (1.70 × 1.70) = 24.2. If you enter pounds, feet or inches, they are first converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm).

What are the BMI categories for adults?

The World Health Organization’s adult categories are: below 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or more obesity. Obesity is further split into class I (30 to 34.9), class II (35 to 39.9) and class III (40 or more).

Is BMI accurate?

BMI is a quick screening measure, not a diagnosis. It doesn’t measure body fat or where fat is carried, so it can be misleading for very muscular people, older adults and others. A doctor looks at more than BMI to judge health.

Can I use this BMI calculator for children or teenagers?

No. These categories are for adults aged 18 and over. For children and teenagers, BMI is compared with growth charts for their age and sex, which this calculator doesn’t do. Ask a doctor or health worker instead.

Are the BMI cut-offs different for South Asians?

A WHO expert consultation in 2004 noted that many Asian populations have a higher risk of health problems at a lower BMI than the standard cut-offs suggest, and proposed additional public-health cut-off points of 23 and 27.5. This calculator uses the standard WHO categories, so treat that as background and ask a doctor what it means for you.

Why does the calculator reject some heights and weights?

To catch typing mistakes, it accepts heights from 50 to 272 cm and weights from 2 to 650 kg. These are limits for checking input, not medical limits. If you enter feet and inches, inches must be below 12.

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