BMI Calculator
Calculate body mass index from metric kilograms and centimeters or imperial pounds and inches. WHO-style adult categories appear with the index. Not medical advice.
1. Enter values
2. Result
Body mass index
22.9
Normal
Metric (kg, cm)
3. Summary
How is it calculated?
Metric BMI is kilograms divided by height in meters squared. Imperial uses 703 × lb / in². Category bands are WHO adult cutoffs for screening, not a diagnosis.
Common use cases
Screening
Get a WHO-style adult BMI band from weight and height.
Fitness tracking
Compare a ratio over time — it is not body fat.
Clinic forms
Fill a BMI field locally before an appointment.
Unit switching
Use kg/cm or lb/in. Switching does not convert typed numbers.
Imperial inches
Convert 5′9″ to 69 inches before you calculate.
A starting point
Treat the label as a conversation starter, not a verdict.
Your data stays private
Weight and height are calculated locally in your browser. Nothing is uploaded or stored on a server.
About body mass index (BMI)
BMI is a screening ratio of mass to height squared. It is not body fat, not fitness, and not a diagnosis. WHO adult bands used here are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese. Those cutoffs were built for populations, not for athletes with high muscle mass, pregnant people, or many children. Pediatric BMI uses age-and-sex percentiles this tool does not compute.
Metric mode is kilograms and centimeters (height is divided by 100 to get meters). Imperial mode uses the common US formula 703 × lb / in². Switching systems does not convert the numbers you already typed — enter values that match the labels. Height in feet-and-inches should be converted to total inches first (5′9″ = 69 in).
Treat the category label as a conversation starter with a clinician, not a verdict. All arithmetic stays in the browser. We do not store weight or height.
How to calculate BMI
Choose metric or imperial
Metric uses kg and cm. Imperial uses pounds and total inches.
Enter weight and height
Both must be greater than zero. The BMI and WHO-style category update as you type.
Copy the index
Copy the number, or tap an example. Calculate jumps to the result on a small screen.
Health data stays local
Measurements never leave this tab. This is not medical advice.
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BMI Calculator FAQ
Metric mode is kilograms / meters², with height typed in centimeters (divided by 100). Imperial mode is the common US formula 703 × lb / in², with height in total inches (5′9″ = 69). Switching systems does not convert numbers already in the fields — re-enter values that match the labels. Both weight and height must be greater than zero.
No. They follow WHO adult bands (under 18.5, 18.5–24.9, 25–29.9, 30+). Those cutoffs are population screens, not body-fat tests. They misfit many athletes, pregnant people, and children. Pediatric BMI uses age-and-sex percentiles this tool does not compute. Talk to a clinician before acting on a number.
No. Weight and height are calculated locally in your browser. Nothing is uploaded or stored on a server. This is not medical advice.