Healthy Primix
Free health tool

BMI Calculator

BMI is your weight in kilograms divided by your height in metres squared. For most adults, a BMI of 18.5 to 24.9 is in the healthy range. It is a quick screening number, not a diagnosis.

Units
cm
kg
BMI cut-offs

*Used by the NHS for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background, who have a higher risk of some conditions at lower BMI.

Enter your height and weight to see your BMI. For adults aged 18 and over.

Calculated in your browser. Nothing you enter is sent or stored.

How this tool works

  1. 1Enter your height and weight in metric or imperial units.
  2. 2Imperial values are converted to kilograms and centimetres first.
  3. 3BMI = weight (kg) ÷ height (m)², rounded to one decimal place.
  4. 4The result is compared with the adult categories below. You can switch to the lower cut-offs the NHS uses for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background.

Formula: BMI = weight (kg) ÷ [height (m)]²

Limitations

  • For adults aged 18 and over only. Children and teenagers need age- and sex-specific BMI charts.
  • BMI does not distinguish muscle from fat, so very muscular people can score high.
  • It does not show where fat is stored. Waist size adds useful information.
  • Not suitable during pregnancy.

Sources

  1. Adult BMI Categories (opens in a new tab) — CDC
  2. Obesity and overweight — fact sheet (opens in a new tab) — World Health Organization
  3. Overweight and obesity in adults (opens in a new tab) — NHS