BMI Calculator
Body Mass Index with WHO category thresholds.
Your BMI
24.7
Normal
WHO range: 18.5 - 24.9
UnderweightNormalOverweightObese
How the bmi calculator works
Body Mass Index (BMI) is weight in kilograms divided by height in metres squared. It is a quick population-level screen for underweight and overweight, used by the NHS and the World Health Organization.
The WHO cut-offs are: below 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or above obese. These thresholds come from associations between BMI and health risk across large populations.
BMI does not distinguish muscle from fat and does not account for where fat is stored. A muscular athlete can read as overweight while carrying low body fat, so pair BMI with a measure like waist circumference or the body fat calculator.
- BMI is a screening tool, not a diagnosis. It works best across groups, less well for any single person.
- The NHS notes BMI cut-offs differ for some ethnic groups; people of South Asian, Chinese and some other backgrounds may face raised health risk from a BMI of 23 upward.
- For a fuller picture, combine BMI with waist measurement or body fat percentage.
Frequently asked questions
Not always. BMI cannot tell muscle from fat, so muscular athletes often score as overweight despite low body fat. Use a body fat estimate alongside it.
The WHO defines 18.5 to 24.9 as the healthy range for most adults. Below 18.5 is underweight and 25 or above is overweight.
The NHS advises that people of South Asian, Chinese and some other backgrounds may have increased health risk at a lower BMI, from around 23, so lower action points can apply.