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BMI Calculator: Body Mass Index and Healthy Weight Range

This free BMI calculator works out your body mass index from your height and weight in kilograms and centimetres, or pounds and inches. It shows the WHO category and the weight range that gives a healthy BMI for your height.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is It and When Do You Need It?

BMI compares your weight with your height in one number. Doctors use it as a quick screening step, and many people use it to track change over time. It does not measure fat directly, so it is best read alongside waist size, fitness and medical advice.

Enter your height and weight in metric or imperial units. You get your BMI, the WHO group and the weight range for a BMI of 18.5 to 24.9.

How to Use This Tool

  1. Choose metric or imperial.
  2. Enter your weight.
  3. Enter your height in centimetres, or in feet and inches for imperial.
  4. Press Calculate.

How the Calculation Works

BMI = weight (kg) ÷ height (m)². For imperial units, the tool converts pounds to kilograms (÷ 2.20462) and inches to centimetres (× 2.54) first. The healthy range is the weights that give a BMI between 18.5 and 24.9 at your height.

Worked Example

A person who is 170 cm tall and weighs 70 kg has a BMI of 70 ÷ 1.7² = 24.2, which is in the normal range. The healthy weight range for 170 cm is about 53.5 to 72.0 kg.

Common Uses

  • A quick health check.
  • Tracking progress over time.
  • Setting a target weight range.
  • Form fields that ask for BMI.

Tips and Common Mistakes

  • BMI is a screen, not a diagnosis.
  • Waist size gives extra information.
  • Muscular people can have a high BMI and be healthy.

Next, you may need the ideal weight calculator, BMR and TDEE calculator, body fat calculator, calorie deficit calculator.

Everything runs in your browser. Nothing you type is uploaded, stored or sent to any outside service.

Frequently Asked Questions

Body mass index is your weight in kilograms divided by your height in metres squared. It is a simple screening number, not a measure of health on its own.
For adults, the WHO groups are under 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, and 30 or more obesity.
No. It does not separate muscle from fat, so athletes can read high, and it does not suit children, pregnant women or older adults in the same way. Some Asian guidelines use lower cut-offs.
No. Use it as a starting point and talk to a doctor about your health.

Disclaimer: results are calculated in your browser from the numbers you enter. Check important results before you rely on them for money, health, safety or legal decisions.