Wyvek

BMI Calculator

Calculate body mass index in metric or imperial.

— BMI
Enter your details

Fill in your height and weight above to see your body mass index.

  • Underweight < 18.5
  • Normal weight 18.5 – 24.9
  • Overweight 25 – 29.9
  • Obesity ≥ 30

Disclaimer: BMI is a general screening tool, not medical advice or a diagnosis. It does not measure body fat directly and may be inaccurate for athletes, children, older adults, and pregnant people. Consult a qualified healthcare professional about your individual health.

Free online BMI calculator

This BMI calculator works out your Body Mass Index instantly from your height and weight, in either metric or imperial units, and shows which World Health Organization weight category you fall into. BMI is a quick, widely used screening number that estimates whether your weight is in a healthy range for your height. Enter your details and the result updates live — nothing is sent to a server, so your numbers stay private on your device.

How to calculate your BMI

  1. Choose Metric or Imperial using the toggle.
  2. For metric, enter your height in centimetres and weight in kilograms.
  3. For imperial, enter your height in feet and inches, plus your weight in pounds.
  4. Read your BMI, shown to one decimal place, and the colour-coded category badge.
  5. Click Copy result to save your BMI and category to the clipboard.

Understanding your result

A BMI under 18.5 is classed as underweight, 18.5–24.9 as a normal or healthy weight, 25–29.9 as overweight, and 30 or above as obesity. Because BMI uses only height and weight, it cannot tell muscle from fat — treat it as a starting point for a conversation with your doctor rather than a complete picture of health.

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Frequently asked questions

What is BMI and how is it calculated?

BMI (Body Mass Index) is a simple ratio of your weight to your height. In metric units it is your weight in kilograms divided by your height in metres squared (kg/m²). In imperial units it is 703 times your weight in pounds divided by your height in inches squared. This calculator does the maths for you and shows your result to one decimal place.

What are the BMI weight categories?

The World Health Organization (WHO) uses four adult ranges: underweight is a BMI below 18.5, normal or healthy weight is 18.5 to 24.9, overweight is 25 to 29.9, and obesity is 30 or above. This tool highlights which band your result falls into.

Is BMI accurate for everyone?

No. BMI is a general screening tool, not a diagnosis. It does not distinguish muscle from fat, so very muscular people may read as overweight, and it can be less reliable for athletes, pregnant people, older adults, and children. Always talk to a healthcare professional about your individual health.

What is a healthy BMI range?

For most adults a BMI between 18.5 and 24.9 is considered a healthy weight range. Sitting inside this band is associated with lower risk for many weight-related conditions, but it is only one of many indicators of overall health.

Does this BMI calculator store my data?

No. Every calculation happens locally in your browser using JavaScript. Your height and weight are never uploaded, saved, or shared, so the tool is completely private and free to use.

How do I convert between metric and imperial?

Use the Metric / Imperial toggle at the top. Metric asks for height in centimetres and weight in kilograms, while Imperial asks for height in feet and inches plus weight in pounds. Your BMI result is the same regardless of which units you enter.

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