Copied!
Home Tools Blog FAQ Contact
⚖️ Health · WHO Standard

Free BMI Calculator
Body Mass Index

Enter your weight and height to instantly calculate your BMI and get your WHO health category — underweight, normal, overweight or obese.

⚡ Instant results 🔒 100% private 📏 Metric & Imperial 🌍 WHO standard
⚖️
BMI Calculator
Body Mass Index — WHO Standard Formula
kg
cm

Frequently Asked Questions

What is the BMI formula?
BMI (Body Mass Index) is calculated by dividing weight in kilograms by height in meters squared: BMI = weight(kg) / height²(m). For imperial units, the formula is: BMI = 703 × weight(lbs) / height²(inches).
What is a healthy BMI range?
According to the World Health Organization (WHO), a healthy or normal BMI is between 18.5 and 24.9. Below 18.5 indicates underweight, 25–29.9 indicates overweight, and 30 or above indicates obesity.
Is BMI accurate for everyone?
BMI is a useful population-level screening tool, but it has limitations for individuals. It does not differentiate between fat mass and muscle mass, so athletes may show a high BMI despite being healthy. It may also be less accurate for the elderly, children, and pregnant women.
What health risks are associated with abnormal BMI?
Being underweight (BMI < 18.5) can indicate malnutrition, weakened immune function, or eating disorders. Being overweight or obese (BMI ≥ 25) is associated with increased risk of type 2 diabetes, heart disease, hypertension, certain cancers, and sleep apnea. However, a single BMI reading should not be the sole basis for health decisions.
Is my data stored or sent anywhere?
No. All calculations are performed directly in your browser using JavaScript. No data is ever transmitted to our servers. Your privacy is fully protected — boxetool never collects or stores personal health information.