BMI Calculator

Enter your height and weight to see your body mass index, WHO category and healthy weight range. Free, instant, private.

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Underweight <18.5Normal 18.5–24.9Overweight 25–29.9Obese 30+
BMI is a general screening measure, not a diagnosis. It does not account for muscle mass, body composition, age, sex or ethnicity. For any decisions about your health, please consult a qualified healthcare professional.

How to use the BMI Calculator

  1. Choose metric (centimeters and kilograms) or imperial (feet, inches and pounds).
  2. Enter your height and weight; the BMI value updates live as you type.
  3. Read your WHO weight category and see where you fall on the visual scale.
  4. Check the healthy weight range shown for your height for extra context.

Why use ZillaKit's BMI Calculator?

Body mass index is a simple, widely used screening figure that relates your weight to your height, calculated as weight in kilograms divided by height in meters squared. This calculator supports both metric and imperial input, converts everything precisely, and classifies the result using the standard World Health Organization categories: underweight below 18.5, normal weight from 18.5 to 24.9, overweight from 25 to 29.9, and obese at 30 or above. It also shows the healthy weight range for your specific height so you can see the numbers in context rather than just a single label, and a visual scale bar places your value along the spectrum at a glance. BMI is a useful starting point at a population level, but it is a blunt instrument for any individual because it cannot tell muscle from fat and does not reflect where weight is carried, age, sex or ethnic differences. That is why the results here are framed as information only. Everything runs instantly and privately in your browser, with no upload, no signup and no data stored.

FAQ

How is BMI calculated?

BMI equals weight in kilograms divided by the square of height in meters. For imperial units the equivalent formula is 703 times weight in pounds divided by height in inches squared. For example, 70 kg at 1.75 m gives a BMI of about 22.9.

What are the BMI categories?

Under the WHO scale, below 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight and 30 or above is obese.

Is BMI accurate for everyone?

No. BMI is a screening tool, not a diagnosis. It does not distinguish muscle from fat and can be misleading for athletes, older adults, pregnant people and some ethnic groups. Always consult a healthcare professional for a full assessment.

Is my height and weight uploaded anywhere?

No. The calculation happens entirely in your browser using JavaScript. Nothing you enter is sent to a server or saved.