Body composition
BMI Calculator
Body Mass Index estimates whether your weight is in a typical range for your height. Enter your details below for an instant result.
Body composition
Body Mass Index estimates whether your weight is in a typical range for your height. Enter your details below for an instant result.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
These ranges are the World Health Organization's standard adult classifications and may not apply the same way to children, pregnant women, or highly muscular individuals.
Body Mass Index (BMI) is a simple calculation that uses your height and weight to estimate whether your body weight falls into a typical range. It was developed in the 1830s and is still used today by doctors, insurers, and researchers as a quick screening tool — not a diagnosis.
The formula is weight in kilograms divided by height in meters squared: BMI = weight (kg) ÷ height (m)². For imperial units, the formula multiplies weight in pounds by 703, then divides by height in inches squared. Our calculator above handles the conversion for you.
BMI sorts results into four broad bands: underweight, normal weight, overweight, and obese. These bands are useful for spotting population-level trends and flagging when a closer look might be worthwhile, but BMI does not measure body fat directly and does not account for muscle mass, bone density, age, or sex.
A muscular athlete can have a "high" BMI while carrying very little body fat, and an older adult can have a "normal" BMI while carrying more fat than is healthy. If you want a closer look at body composition, our Body Fat Calculator uses body measurements instead of just height and weight.
No. BMI is a population-level screening tool. It tends to be less accurate for athletes, older adults, pregnant women, and children, since it can't distinguish between muscle and fat.
For most adults, a BMI between 18.5 and 24.9 is considered within the typical range, according to World Health Organization guidelines. Individual health depends on many more factors than this one number.
BMI can be one data point, but it's best used alongside other measures — like body fat percentage, waist circumference, and how you feel and function day to day. Speak with a healthcare provider before setting specific targets.
No. The calculation runs entirely in your browser. Nothing you enter is saved or transmitted.