BMI Calculator
Find your body mass index from your height and weight, in metric or imperial, and see which healthy-range band you fall into. Calculates instantly in your browser.
Your BMI
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Show the math
BMI is your weight over the square of your height:
BMI = weight (kg) ÷ height (m)²
The healthy band for adults is 18.5–24.9; below is underweight, 25–29.9 is overweight, and 30+ is obesity. BMI is a quick screen, not a diagnosis, it cannot tell muscle from fat, so read it alongside measures like waist-to-height ratio.
What this does
A BMI calculator finds your body mass index from your height and weight, in metric or imperial, and shows which standard weight-status band you fall into.
How it works
Body mass index divides your weight in kilograms by the square of your height in metres. Imperial inputs are converted first, so the result is identical either way.
BMI = weight (kg) ÷ height (m)²
How to use it
- Choose metric or imperial units.
- Enter your height and weight.
- Read your BMI value.
- See which weight-status band it falls in.
Understanding your result
The WHO adult bands are: under 18.5 underweight, 18.5–24.9 healthy weight, 25–29.9 overweight, and 30 or above obesity. BMI is a screening tool, not a diagnosis, it cannot tell muscle from fat.
Example
A person 1.75 m tall weighing 70 kg has a BMI of about 22.9, within the healthy range.
Sources & methodology
- CDC, About Adult BMI, How BMI is used and its limits
- World Health Organization, Body Mass Index, International BMI categories
Last updated .
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). For imperial units the tool converts pounds and inches first, so the result is identical.
What are the BMI categories?
The WHO bands for adults are: under 18.5 underweight, 18.5–24.9 healthy weight, 25–29.9 overweight, and 30 or above obesity.
Is BMI accurate for everyone?
BMI is a quick screen, not a diagnosis. It does not distinguish muscle from fat, so very muscular people can read high while it can understate fat in older adults. Use it alongside other measures.
Do you store my height and weight?
No. Everything is calculated locally in your browser, nothing is uploaded or saved.
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