BMI Calculator
BMI Calculator
Calculate your body mass index, see your adult BMI category, and understand what the number can—and cannot—tell you about your health.
← Explore all free toolsCalculate your BMI
Enter your height and weight. Switch units whenever you like; your measurements will be converted automatically.
The marker is capped at the ends of this visual scale (BMI 15–40).
Calculated from BMI 18.5 to below 25. This is a population reference, not a personalized goal or medical recommendation.
Understanding your BMI result
BMI is calculated as weight in kilograms divided by height in meters squared. The following standard adult categories apply to people aged 20 and over. They are screening ranges, not diagnoses.
How to calculate BMI by hand
Example: 70 kg ÷ (1.70 m × 1.70 m) = 24.2. For US units, BMI = weight (lb) ÷ height (in)² × 703 (approximately).
What about BMI 30 or higher?
The adult obesity range is further divided into classes: Class 1 (30–<35), Class 2 (35–<40), and Class 3 (40+). This still doesn’t replace an individual clinical assessment.
Questions people ask about BMI
Is BMI an accurate measure of body fat?
No. It doesn’t directly measure fat, muscle, or body-fat distribution. It’s one screening indicator to interpret with other information about your health.
Can someone with a healthy BMI still have health risks?
Yes. Blood pressure, blood sugar, cholesterol, family history, habits, and waist measurements may matter independently of BMI.
Can children or teenagers use this calculator?
This page uses adult categories for ages 20+. For ages 2–19, BMI must be interpreted using age- and sex-specific percentiles, not these adult cutoffs.
What if I’m pregnant or very muscular?
Standard adult BMI categories may be less informative during pregnancy or for people with high muscle mass. Your healthcare professional can recommend better context.