UnderweightBMI Below 18.5
FREE HEALTH SCREENING TOOL
BMI & Healthy Weight Calculator
Enter your measurements and see where your result sits on the adult BMI scale.
YOUR MEASUREMENTSEnter your measurements
Private by design · your entries are not saved
LIVE BMI RATINGReady for your details
Your BMI0Ready to calculate
UNDERSTAND THE NUMBER
Adult BMI categories
BMI is calculated as weight in kilograms divided by height in metres squared. These categories are used for adults aged 20 and above.
Healthy weightBMI 18.5–24.9
OverweightBMI 25.0–29.9
Obesity, class 1BMI 30.0–34.9
Obesity, class 2BMI 35.0–39.9
Obesity, class 3BMI 40.0 or above
IMPORTANT CONTEXT
When BMI needs careful interpretation
People aged 2–19 need BMI-for-age and sex percentiles. This adult calculator deliberately does not classify them.
BMI may be unsuitable during pregnancy and can misclassify very muscular people, older adults or people with fluid retention, limb loss or some medical conditions.
BMI does not directly measure body fat or where it is stored. Waist size, fitness, diet, sleep, symptoms and clinical tests add important context.
Do not use the result to start extreme dieting or medication. Speak with a qualified health professional if you are worried about your weight, have an eating disorder, are pregnant, or have recent unexplained weight change.
Clinical basis
The calculation and adult categories follow established public-health guidance. Read more from WHO, CDC and NHS.
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