Gauritanaya

BMI calculator

Get your BMI, the category that applies to your background, and a healthy weight range for your height.

Runs entirely in your browser. Nothing you type is sent anywhere.

Height
cm
Weight
kg
years

Some guidelines use lower thresholds for people from certain backgrounds. Choose the one that fits your family background, not where you live.

Waist (optional)
cm

Adds your waist-to-height ratio.

Your BMI—

Ranges used
—
Healthy weight for your height
—

For general wellness only. These results are estimates from published formulas and guidelines, not a diagnosis or medical advice. They may not suit pregnancy, children, older adults, athletes or people with health conditions. Talk to a qualified health professional about your health. In an emergency, call your local emergency number.

How to use the BMI calculator

BMI is weight in kilograms divided by the square of height in metres. Body build and health risk at a given BMI differ between populations, so several standards exist, and the tool uses the one that matches your family background (you can choose another). WHO international ranges: healthy 18.5–24.9, overweight 25–29.9, obesity 30 and over. NICE (UK) uses overweight from 23 and obesity from 27.5 for South Asian, Chinese, other Asian, Middle Eastern, Black African and African-Caribbean adults. The Indian consensus (2009) uses overweight 23–24.9 and obesity 25 and over; China uses 24 and 28; Japan, the WHO Asia-Pacific guidance and Korea use 23 and 25, with Korea adding obesity classes from 30 and 35. The table below the result shows your category under every standard. Waist-to-height ratio uses the NICE bands: 0.4–0.49 healthy, 0.5–0.59 increased, 0.6 or more high.

  1. Choose metric or imperial units.
  2. Enter your height and weight, and your age.
  3. Optionally choose your family background and add your waist measurement.
  4. Read your BMI, the ranges used and the healthy weight range for your height.

Understanding your result

Your category depends on the ranges used: the WHO ranges for most adults, or the lower NICE thresholds if you chose one of the listed family backgrounds. A result in the overweight or obesity range is a prompt to look at your waist size and talk to a health professional, not a diagnosis. The healthy weight range shows the weights that would give a healthy BMI at your height.

Sources

Sources checked on 9 October 2026. Formulas and thresholds are used as published; the wording on this page is our own.

Questions

Why does my background change the result?
Studies in many countries found that people from some backgrounds face higher health risks at a lower BMI, so national and international bodies set lower cut-offs for them. The tool picks the standard for your family background: India’s for South Asian, China’s for Chinese, Japan’s and Korea’s for Japanese and Korean, the WHO Asia-Pacific ranges for other Asian, NICE’s for Middle Eastern and Black backgrounds, and WHO’s otherwise. You can choose any other standard, and the table shows them all.
Why do the standards disagree?
Each was set from different studies and populations, and for different purposes (screening, public health or diagnosis). A BMI of 26 is “overweight” under WHO but “obesity” under the Indian, Japanese and Korean standards. Treat the category as a prompt to check your waist and talk to a health professional, not as a diagnosis.
Can children and teenagers use this?
They can see their BMI number, but under 18 it must be compared with age- and sex-specific growth charts, so this tool doesn’t give a category. A child’s doctor or nurse can plot it for you.
Does BMI apply during pregnancy?
No. Weight gain in pregnancy is assessed against your pre-pregnancy BMI, so the category is switched off when you tick “I’m pregnant”.
Why add my waist?
BMI can’t tell muscle from fat or show where fat is stored. NICE recommends also checking waist-to-height ratio. Keeping your waist under half your height is the general guide, and NICE says the same 0.5 boundary applies to all ethnicities and sexes.
Is this a diagnosis?
No. It compares your numbers with published ranges for general wellness. Only a qualified health professional can assess your health, taking your history and other tests into account.

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