BMI Calculator
Enter your height and weight to calculate your Body Mass Index and see which category it falls into.
What is BMI and how is it calculated?
Body Mass Index (BMI) is a simple screening measure that relates your weight to your height. In metric units, BMI equals weight in kilograms divided by height in meters squared (kg/m²). In imperial units, it's 703 × weight in pounds, divided by height in inches squared. The World Health Organization uses four broad categories for adults: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25–29.9), and obese (30 and above).
What BMI does not measure
BMI does not distinguish between muscle and fat, and it does not account for where fat is distributed on the body. A muscular athlete can register as "overweight" despite having low body fat, and an older adult with reduced muscle mass can have a "healthy" BMI while carrying more fat than ideal. It also doesn't apply the same way across all populations — some health organizations use adjusted thresholds for different ethnic groups.
How to use your result
Treat BMI as a starting point, not a diagnosis. If your result is outside the healthy range, or if you have concerns about your weight regardless of what the number says, talk to a healthcare provider who can look at the full picture — body composition, waist circumference, activity level and overall health.
Frequently asked questions
How is BMI calculated?
BMI = weight in kilograms divided by height in meters squared (kg/m²). For imperial units, BMI = 703 × weight in pounds divided by height in inches squared.
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range, according to the World Health Organization's standard classification.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so it can overestimate body fat in athletes and underestimate it in older adults who have lost muscle mass. It is a screening tool, not a diagnosis.
Should children use this calculator?
This calculator uses the adult BMI categories. Children and teens need age- and sex-specific percentile charts instead — consult a pediatrician.
Is my data saved anywhere?
No. Your height and weight are used only in your browser to compute the result and are never sent to a server or stored.