BMI calculator

Enter your height and weight to see your body mass index (BMI) and the healthy weight range for your height.

What's your sex?
How old are you?
How tall are you?
What's your current weight?

For adults 18 and over. An estimate, not medical advice.

Keep an eye on your BMI

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How BMI is calculated

BMI is your weight in kilograms divided by your height in metres, squared. In pounds and inches, multiply by 703.

For example, someone 1.70 m tall who weighs 65 kg has a BMI of 65 ÷ 1.70² = 22.5.

BMI = weight (kg) ÷ height (m)²BMI = 703 × weight (lb) ÷ height (in)²

What your BMI means

Adult BMI falls into four ranges, using the cut-offs set by the World Health Organization. They're the same for women and men.

BMIRange
Below 18.5Underweight
18.5 – 24.9Healthy weight
25 – 29.9Overweight
30 and aboveObesity

What BMI doesn't tell you

BMI is a quick screening number, not a diagnosis. It can't tell muscle from fat or show where your body stores fat, so very muscular people can score high.

Health risk can start at a lower BMI for some ethnic groups, including people of South Asian, Chinese, Middle Eastern, Black African or African-Caribbean background. BMI for children and teens uses age-based charts instead.

If you're unsure what your result means for you, a doctor can look at the full picture.

Questions

What is a healthy BMI?

For most adults, a BMI from 18.5 to 24.9 is in the healthy weight range, according to the World Health Organization.

Is BMI accurate?

It's a useful starting point for most adults, but it has limits. It doesn't measure body fat directly, so muscular people can have a high BMI, and some groups have more health risk at a lower BMI. Waist size adds useful context.

Can I use this BMI calculator for children?

No. This calculator is for adults aged 18 and over. Children and teens need a BMI-for-age percentile, which allows for growth. Ask a doctor or use a child BMI tool.

Is BMI different for women and men?

No. Adults use the same formula and the same ranges, whatever their sex.

Sources

  1. World Health Organization: Obesity and overweight
  2. CDC: Adult BMI categories
  3. NHS: BMI calculator for adults

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