BMI Calculator

BMI, or Body Mass Index, is a single number derived from two everyday measurements: your weight and your height. The index is computed as weight in kilograms divided by the square of height in meters, and the result is compared against the classification scale published by the World Health Organization, which sorts adults into five bands from underweight through class II obesity. This calculator does that math for you, adds the healthy weight range for your exact height, and accepts measurements in either the metric or the imperial system. It is aimed at people tracking their weight, preparing for a check-up, or simply wanting a factual starting point — no account, no signup, nothing is sent anywhere.

What this tool can do

• 📏 Accepts both metric and imperial input — centimeters and kilograms, or feet, inches, and pounds — and handles the conversion itself.
• ⚖️ Computes the BMI to one decimal place with the standard weight-over-height-squared formula.
• 🏷️ Places the result in one of five WHO categories, from underweight to class II obesity.
• 🎯 Shows the ideal weight range (lower and upper bound) for your exact height.
• 📊 Includes a visual scale marking the boundaries between the categories.

When would you use it

• 🩺 Before a medical check-up, to have a concrete figure to discuss with the doctor.
• 🏋️ Tracking weight-loss progress without keeping a spreadsheet.
• 📈 Checking periodically whether your weight is drifting toward a new category.
• 👨‍👩‍👧 Getting a reference number for a child’s weight relative to height (child-specific norms differ from the adult scale).

Everything is computed locally in your browser: the numbers you type are never uploaded, stored, or shared, and reloading the page starts fresh. One honest limitation: BMI is a screening index, not a body-composition measurement. A muscular build can land in the overweight band despite a healthy body-fat level, and the categories are calibrated for adults — they say nothing about fitness or health on their own, so treat the result as a reference point, not a diagnosis.

• Muscle weighs more than fat: athletes routinely land in the overweight band at perfectly healthy body fat.
• Children and teens need age-and-sex percentile charts, not the adult table this page shows.
• Pregnancy, oedema and very short or tall frames all skew the ratio — pair it with waist measurement before drawing conclusions.