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BMI calculator
A quick body mass index in metric or imperial units — plus a clear note on what it means before anesthesia. BMI is a rough screen, not a verdict on your health.
Frequently asked questions
Why does the anesthesia team ask about my BMI before surgery?
Body weight affects how anesthetic drugs are dosed, how your airway and breathing are managed, and the chance of conditions like sleep apnea. A higher (or very low) BMI is rarely a barrier to surgery — it just helps your team plan the safest anesthetic for you.
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared (kg/m²). In imperial units it's 703 × weight in pounds ÷ height in inches squared. This tool does the maths for you in either unit.
Is BMI a perfect measure of health?
No. BMI is a quick screen, not a diagnosis. It doesn't separate muscle from fat, so very muscular people can read 'high' while being healthy, and it doesn't show where fat is carried. Your team looks at the whole picture, not just this number.