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Adult BMI calculator.

Height and weight give you one screening measure. They don’t sum up your health—or you.

For adults aged 20 and older. Not for children, teens or interpreting weight during pregnancy.

Enter your measurements to see your BMI.

Calculated on your device. Measurements and results are not saved or sent to us.

What the ranges mean

Below 18.5
Underweight

18.5 to below 25
Healthy weight

25 to below 30
Overweight

30 and above
Obesity

These are standard CDC adult categories, not a diagnosis or a recommended goal. The category uses the unrounded result; the displayed BMI is rounded to two decimals.

Same calculation. Different clinical context.

Your country does not change the BMI formula. Guidance can vary by health authority and the population being assessed; nationality and ancestry are not interchangeable.

Examples of adult guidance—not a complete world directory
Framework	Overweight starts	Obesity starts	Context
Standard CDC / WHO categories	25	30	Common international reference, including US and European reporting.
Australia: healthdirect	25	30	Notes limitations for several ancestry groups; country alone does not determine personal risk.
UK NICE: specified ancestry groups	23	27.5	South Asian, Chinese, other Asian, Middle Eastern, Black African and African–Caribbean backgrounds. Applicable context depends on the person, wherever they live.

These are screening categories, not sharp biological boundaries. A BMI below a threshold does not guarantee low risk. Local clinical guidance may use other thresholds for particular purposes.

NICE recommendations 1.9.10–1.9.13 · Australia: healthdirect · WHO Europe reporting

Keep the context

BMI cannot distinguish muscle from fat or show where fat is carried. Health assessment also considers medical history, examination and other measurements. The calculator reports your selected framework, with standard categories as the default. The comparison above explains alternative clinical thresholds without assuming your ancestry from your location. A clinician can help interpret your result.

How is BMI calculated?

BMI = weight in kilograms ÷ height in metres squared. For imperial inputs, we convert pounds to kilograms and feet/inches to metres before calculating.

Sources & next steps

CDC: adult BMI categories · CDC: what BMI can and cannot tell you

Prefer a practical food tool? Try the portion calculator, or understand everyday serving sizes.

Updated 6 October 2026. General education; not clinically reviewed.