BMI Calculator
Body Mass Index from height and weight. Metric or US units. Healthy range and BMI Prime.
BMI
24.2 kg/m²
Normal
- Healthy BMI18.5 – 24.9 kg/m²
- Healthy weight53.5 – 72.0 kg
- BMI Prime0.97
- Ponderal Index14.2 kg/m³
This is a WHO adult BMI screen, not a diagnosis.
How it works
Pick units
Metric uses centimetres and kilograms. US uses feet, inches, and pounds. Switching converts the values you already typed.
Enter height and weight
Fields accept numbers only. BMI, the WHO category, and the extras update as you type.
Copy the result
Copy sits on the BMI value.
What is BMI?
Body Mass Index is weight divided by height squared. The World Health Organization uses it as a quick adult screen: underweight below 18.5, normal through 24.9, overweight from 25, obesity from 30. This page also lists a healthy weight for the height you typed, BMI Prime (BMI ÷ 25), and the Ponderal Index (kg/m³). It is not a diagnosis.
Why use this tool
- Metric and US units, converted when you switch
- WHO adult bands: underweight, normal, overweight, obesity
- Healthy weight for the height you entered
- BMI Prime and Ponderal Index
- Copy on the result. No account. Unlimited on the free plan
Questions
What does BMI Calculator do?
It computes adult Body Mass Index from height and weight: kg ÷ m², or 703 × lb ÷ in². It also shows the WHO category, a healthy weight band, BMI Prime, and Ponderal Index.
How do I use BMI Calculator?
Choose metric or US, type height and weight. Letters are ignored. The result updates as you type. Copy sits on the BMI.
What is the formula?
Metric: weight in kilograms divided by height in metres squared. US: 703 × pounds ÷ inches squared. Both equal kg/m².
What do the categories mean?
WHO adult cut-offs: underweight below 18.5, normal 18.5–24.9, overweight 25–29.9, obesity 30 and above. The bar marks where your value sits.
What is a healthy weight here?
The weight range that would put BMI between 18.5 and 24.9 at the height you entered. It is a screening band, not a target for every body.
What is BMI Prime?
BMI divided by 25, the top of the normal band. Below 1 is inside or under that band; above 1 is overweight or higher.
What is the Ponderal Index?
Mass divided by height cubed (kg/m³). It scales differently from BMI for very short or tall adults.
Why is there no age or sex?
Standard adult BMI uses only height and weight. Child BMI uses percentiles. This page is the adult screen.
Is this medical advice?
No. BMI is a population screen. Muscle, age, and some ethnic groups sit outside these bands. A clinician reads it in context.
Is there a daily limit?
No. There is no daily cap on this tool.
Do I need an account?
No. Open the page and use it.
Does it work on a phone?
Yes. It runs in the mobile browser.
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