BMI calculator
Your BMI, its WHO category and a healthy weight range for your height.
How it works
- 01Choose cm and kg or feet and pounds.
- 02Enter your height and weight. Your BMI and category appear right away.
- 03Check the healthy weight range for your height, and read what BMI can and can't tell you.
Questions
›How is BMI calculated?
BMI is your weight in kilograms divided by your height in meters squared. In imperial units it is 703 × weight in pounds ÷ height in inches squared. Both give the same number.
›What is a healthy BMI?
For adults, the World Health Organization classes 18.5 to 24.9 as a healthy weight, 25 to 29.9 as overweight and 30 or more as obesity, split into three classes. Some guidelines use lower thresholds for people of certain ethnic backgrounds, because health risks start at a lower BMI for them.
›Is BMI accurate?
It is a quick screening number, not a measure of body fat or health. It can't tell muscle from fat, so very muscular people can read as overweight, and it can miss extra fat in older adults. It is not meant for pregnancy. Treat it as a starting point for a conversation with a doctor, not a diagnosis.
›Can I use it for a child or teenager?
Not with the adult categories. Under 20, BMI is compared with others of the same age and sex on growth charts and given as a percentile. This calculator shows the number but doesn't work out percentiles; a doctor, or the CDC's BMI calculator for children and teens, can.
›Is my data uploaded anywhere?
No. This tool runs entirely in your browser, and Rounder never sends what you type or drop in to a server, ours or anyone else's. Once the page has loaded, along with any AI model the tool uses, it even works offline.