BMI Calculator
Within the WHO normal (healthy) range.
BMI is a screening tool, not a medical diagnosis. It does not measure body fat directly and may misclassify muscular adults. Talk to a clinician for personalized advice.
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Browse allWhat Is a BMI Calculator?
A BMI calculator (Body Mass Index calculator) estimates weight relative to height using a simple formula. Health organizations use BMI categories to flag underweight, healthy, overweight, and obesity ranges for most adults.
BMI Formula
Adult BMI Categories (WHO)
- Underweight: BMI < 18.5
- Normal: 18.5 – 24.9
- Overweight: 25 – 29.9
- Obesity I / II / III: 30–34.9 / 35–39.9 / 40+
Frequently Asked Questions
How do you calculate BMI?
Divide weight in kilograms by height in meters squared. Or use 703 × lb ÷ inches².
What is a healthy BMI?
For most adults, 18.5–24.9 is the normal (healthy) range.
Is BMI accurate for athletes?
Not always — muscle raises weight without meaning excess fat. Use additional measures.
Can children use this calculator?
No — kids need age- and sex-specific BMI percentiles, not adult cutoffs.
Is this BMI calculator free?
Yes — free, private, no account required.