bmi calculator
enter your weight and height in metric or imperial units to get your body mass index and category.
runs on your device · free · no sign-up
loading tool…
how to bmi calculator
- choose metric (kg and cm) or imperial (lb, feet and inches).
- enter your weight and height.
- read your bmi, category and the weight range that sits in the normal band for your height.
- optional: tick compare two scenarios to put a goal weight next to your current weight and see both on the chart.
bmi is weight divided by height squared. it was designed for studying populations, not for diagnosing individuals, and it works best as a quick screen. a result in the 18.5 to 24.9 range is considered normal for adults, 25 to 29.9 overweight and 30 or more obese. under 18.5 is underweight.
what it misses is a long list: muscle mass, bone structure, age, where fat is stored and ethnicity. some guidelines use lower cut-offs for people of south and east asian descent because health risks rise at a lower bmi. waist circumference, blood pressure, blood tests and how you feel are often more useful than one number.
this calculator is for adults and does not give medical advice. if your result worries you, or you are pregnant, very young or old, or training heavily, talk to a doctor or dietitian instead of relying on it.
features
- metric and imperial units that convert as you switch
- who bmi categories and a healthy-weight range for your height
- scale chart showing where you sit, with an optional second marker
- compare two scenarios, such as now and goal
- share link that stores only the numbers you typed
popular uses
frequently asked questions
how is bmi calculated?
BMI = weight in kilograms divided by height in meters squared. in pounds and inches it is 703 × lb ÷ in².
what is a healthy bmi?
for adults, 18.5 to 24.9 is considered the normal range, under 18.5 underweight, 25-29.9 overweight and 30 or more obese.
is bmi accurate?
it is a simple screening estimate. it ignores muscle mass, age and body shape, so it is not a diagnosis. talk to a health professional about your health.
is bmi different for men and women?
not for adults. the same cut-offs (18.5, 25 and 30) apply to men and women over 18. at the same bmi, women on average carry more body fat than men, which is one reason bmi is only a rough guide.
can i use bmi for children or teenagers?
no. for people under 20 the number is compared with percentile charts for their age and sex, which this tool does not include. use a paediatrician or national growth charts for children.
why can athletes have a high bmi?
muscle is denser than fat, so a muscular person can weigh a lot for their height and read as overweight even with low body fat. bmi also says nothing about where fat sits, and waist size and fitness often tell you more.