BMI Calculator

Calculate your Body Mass Index in metric or imperial units and see your WHO weight category.

cm
kg
Your BMI
22.9
Normal weight
BMI SCALE
1518.5253040
UnderweightNormalOverweightObese

How to Use the BMI Calculator

Select your preferred units (metric or imperial), enter your height and weight, and your BMI appears instantly along with your weight category and a visual position on the BMI scale.

The BMI Formula

Metric:  BMI = weight (kg) ÷ height (m)²

Imperial:  BMI = (weight (lb) ÷ height (in)²) × 703

For example, a person who is 175 cm tall and weighs 70 kg has a BMI of 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9, which is in the normal range.

BMI Categories (WHO)

BMI RangeCategory
Below 16.0Severe underweight
16.0 – 18.4Underweight
18.5 – 24.9Normal weight
25.0 – 29.9Overweight
30.0 – 34.9Obese (Class 1)
35.0 – 39.9Obese (Class 2)
40.0 and aboveObese (Class 3)

Limitations of BMI

BMI is a simple, widely used screening measure, but it does not tell the whole story. It cannot distinguish muscle from fat, so athletes and muscular individuals may register as overweight despite low body fat. It also does not reflect where fat is distributed, which matters for health risk. For a fuller picture, consider pairing BMI with a body fat estimate and waist measurement, and consult a healthcare professional.

Disclaimer: This tool is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider.

Frequently Asked Questions

What is BMI and how is it calculated?
BMI (Body Mass Index) is a measure of body fat based on height and weight. It is calculated by dividing weight in kilograms by height in meters squared: BMI = kg ÷ m². In imperial units: BMI = (lbs ÷ in²) × 703.
What is a healthy BMI range?
According to the World Health Organization, a healthy BMI for adults is 18.5 to 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat, so very muscular people may have a high BMI without excess fat. It also does not account for age, sex, bone density, or fat distribution.
What BMI is considered obese?
A BMI of 30 or higher is classified as obese. Obesity is further divided into Class 1 (30–34.9), Class 2 (35–39.9), and Class 3 (40 or higher, sometimes called severe obesity).
Does this calculator work for children?
This calculator uses the adult BMI formula. For children and teens (ages 2–19), BMI is interpreted using age- and sex-specific percentile charts, so the standard adult categories do not apply.
Is my data stored or shared?
No. All calculations run entirely in your browser. Nothing you enter is stored, transmitted, or shared.
Is this medical advice?
No. This tool is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult a qualified healthcare provider about your health.

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