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BMI Calculator

Calculate your BMI (Body Mass Index) with WHO classification in 6 categories. Find your ideal weight for your height. Instant and free result.

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BMI Calculator (Body Mass Index)

Calculate your Body Mass Index (BMI) instantly with our free online tool. Simply enter your weight in kilograms and your height in centimeters or meters, and get your BMI value with the WHO classification — from underweight to obesity class III. The tool automatically detects whether your height input is in centimeters or meters, making it easy and error-free.

The formula used is BMI = weight ÷ height² (in kg and meters), the international standard recommended by the World Health Organization (WHO). The WHO classifies BMI into six categories: underweight (below 18.5), normal weight (18.5 to 24.9), overweight (25.0 to 29.9), obesity class I (30.0 to 34.9), obesity class II (35.0 to 39.9), and obesity class III (40.0 and above). Each category is associated with different health risks and recommendations.

In addition to the BMI value and classification, the tool calculates and displays the ideal weight range for your height, based on a healthy BMI between 18.5 and 24.9. A visual color bar with a marker shows exactly where your BMI falls on the spectrum, making it easy to understand your result at a glance.

All calculations are performed 100% in your browser — no data is sent to any server. Your weight and height information never leaves your device, ensuring complete privacy.

Important: BMI is a useful screening tool but does not directly measure body fat. Athletes with high muscle mass may show an elevated BMI while being perfectly healthy. Children, elderly individuals, and pregnant women should use age-specific or condition-specific assessments. For a comprehensive health evaluation, always consult a healthcare professional. If you need other health or calculation tools, try our Percentage Calculator or Character Counter.

Frequently Asked Questions

What is a healthy BMI?
According to the WHO, a healthy BMI is between 18.5 and 24.9. Values below 18.5 indicate underweight, while 25 and above indicate overweight or obesity.
Is BMI accurate for athletes?
BMI does not distinguish between muscle and fat mass. Athletes with high muscle mass may show an elevated BMI while being perfectly healthy. For a more complete assessment, consult a healthcare professional.
Does the BMI calculator work for children?
For children and adolescents (2-19 years), the WHO recommends using age- and sex-specific BMI percentiles rather than the standard adult BMI ranges. This calculator uses the adult formula (weight ÷ height²). For pediatric assessment, consult your pediatrician.