Our free BMI Calculator helps you quickly find your Body Mass Index using your height and weight. Enter your details below to calculate your BMI and see which category your result falls into.
The calculator also shows the standard healthy BMI range, an estimated healthy weight range for your height, BMI Prime, and Ponderal Index. You can use metric or US units depending on your preference.
BMI is a useful screening tool, but it does not measure body fat directly or account for factors such as muscle mass, age, or body composition.
- Healthy BMI range: 18.5 kg/m² – 25 kg/m²
- Healthy weight for the height: 59.9 kg – 81.0 kg
- BMI Prime: 0.80
- Ponderal Index: 11.1 kg/m³
What Is BMI?
Body Mass Index, commonly called BMI, is a number calculated from a person's weight and height. It is commonly used as a simple screening measure to place adults into different weight categories.
For most adults, a BMI between 18.5 and 24.9 is generally considered the normal or healthy range. A BMI below 18.5 is considered underweight, while a BMI of 25 or higher falls into the overweight or obesity categories.
However, BMI is not a complete measure of health. For example, someone with a high amount of muscle may have a higher BMI even though they have relatively little body fat.
BMI Categories for Adults
The standard BMI categories for adults are:
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 or higher | Obesity |
These ranges are intended as general guidelines for adults. BMI is interpreted differently for children and teenagers because their body composition changes as they grow.
How Is BMI Calculated?
For adults using metric units, BMI is calculated by dividing weight in kilograms by height in meters squared.
BMI = Weight (kg) ÷ Height² (m)
For example, a person who weighs 65 kg and is 1.80 meters tall has a BMI of approximately 20.1.
Our calculator performs the calculation automatically, so you don't need to work it out yourself.
Is BMI a Good Measure of Health?
BMI can be useful as a quick screening measurement, but it has limitations. It doesn't distinguish between muscle, fat, bone, and other tissues.
For example, athletes and people with a high amount of muscle can have a higher BMI without having excess body fat. Age, sex, body composition, and other health factors can also affect how meaningful a BMI result is.
For that reason, your BMI should be considered alongside other health information rather than used on its own to determine whether you are healthy.
Frequently Asked Questions
Q1. What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is generally considered the normal or healthy range. However, BMI is only one screening measure and doesn't provide a complete picture of someone's health.
Q2. How do I calculate my BMI?
BMI is calculated by dividing your weight in kilograms by your height in meters squared. For example, if you weigh 65 kg and are 1.80 m tall, your BMI is about 20.1. Our calculator does the calculation for you automatically.
Q3. What does a BMI of 25 mean?
A BMI of 25 falls at the beginning of the overweight category for adults under the standard BMI classification. It doesn't necessarily mean that you have excess body fat because BMI doesn't distinguish between muscle and fat.
Q4. Can BMI be used for children?
BMI can be calculated for children and teenagers, but it is interpreted differently than adult BMI. For people ages 2–19, BMI is normally compared with age- and sex-specific growth charts and reported as a BMI percentile.
Q5. Is BMI the same for men and women?
The standard adult BMI categories are generally the same for men and women. However, BMI doesn't account for differences in body composition, so it should not be considered a complete measure of health for either sex.