Calculate your Body Mass Index using your height and weight. Choose metric or imperial units to calculate your BMI and see the standard adult BMI category ranges.
Enter your height and weight to calculate your BMI.
BMI for children and teens is interpreted differently — using age- and sex-specific growth charts and percentiles rather than the adult categories above. Try our Age Calculator if you need an exact age, and consult a qualified healthcare professional for guidance suited to a child's or teen's BMI.
Your BMI is a screening measure based on your height and weight. BMI does not directly measure body fat and does not account for factors such as muscle mass, body composition, age, or individual health conditions.
Enter your height and weight to calculate your BMI.
BMI for children and teens is interpreted differently — using age- and sex-specific growth charts and percentiles rather than the adult categories above. Try our Age Calculator if you need an exact age, and consult a qualified healthcare professional for guidance suited to a child's or teen's BMI.
Your BMI is a screening measure based on your height and weight. BMI does not directly measure body fat and does not account for factors such as muscle mass, body composition, age, or individual health conditions.
Body Mass Index (BMI) is a number calculated from a person's weight and height. It's used as a general screening measure to place adults into broad weight categories for population-level and general health screening purposes. BMI does not directly measure body fat, and on its own it is not a definitive measure of an individual's health.
The metric BMI formula divides weight in kilograms by height in meters, squared.
For imperial units (pounds and feet/inches), this calculator first converts weight to kilograms and height to meters using the standard conversions (1 lb = 0.45359237 kg, 1 in = 0.0254 m), then applies the same formula — so metric and imperial inputs always produce a consistent result.
| Category | BMI Range |
|---|---|
| Underweight | Below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity | 30.0 or higher |
These ranges are commonly used adult BMI screening categories. They should not be interpreted as a diagnosis or a complete assessment of individual health.
| Weight | Height | BMI | Category |
|---|---|---|---|
| 70 kg | 175 cm | 22.9 | Normal weight |
| 90 kg | 180 cm | 27.8 | Overweight |
| 100 kg | 180 cm | 30.9 | Obesity |
BMI is calculated from height and weight alone, so it does not directly measure body fat percentage, muscle mass, fat distribution, bone density, or individual medical conditions. Because of this, BMI can be less informative for some groups — for example, athletes and other people with a high proportion of muscle mass can have a higher BMI without a correspondingly higher amount of body fat. BMI is best treated as one general screening measure among many, not a complete picture of health.
The adult BMI categories on this page are not appropriate for children and teenagers. In children and teens, BMI is typically interpreted using age- and sex-specific growth charts or percentiles, since healthy body composition changes significantly as children grow. If you'd like to understand a child's or teen's BMI, an appropriate healthcare professional is best placed to interpret it in context.
This is why the calculator above includes an optional Age field. Age never changes the BMI number itself — the formula is the same for everyone — but it changes how that number should be read: entering an age of 18 or older shows the standard adult categories, while entering an age under 18 shows the BMI number without an adult category, since those ranges don't apply. If you need to work out someone's exact age first, Brekzy's Age Calculator can help.
BMI (Body Mass Index) is a number calculated from a person's height and weight. It's a widely used general screening measure, not a diagnosis or a direct measurement of body fat.
BMI is calculated by dividing weight in kilograms by height in meters squared: BMI = weight (kg) ÷ height² (m). For imperial units, weight in pounds and height in feet and inches are converted to kilograms and meters first, then the same formula applies.
A BMI between 18.5 and 24.9 falls into the commonly used "normal weight" screening range for adults. This is a general reference range, not an individual health assessment.
The commonly used adult ranges are: below 18.5 (underweight), 18.5–24.9 (normal weight), 25.0–29.9 (overweight), and 30.0 or higher (obesity). These are general screening categories, not a diagnosis.
Yes. Switch the calculator to Imperial mode to enter your weight in pounds and your height in feet and inches.
BMI is a simple screening tool, not a complete health assessment. It doesn't directly measure body fat, muscle mass, fat distribution, or other individual factors, so it's best used alongside other information rather than on its own.
No. BMI is based only on height and weight, so it can't distinguish muscle from fat. This means BMI can be less informative for people with a lot of muscle mass, such as some athletes.
This calculator uses standard adult BMI categories, which aren't appropriate for children and teens. Children's BMI is typically interpreted using age- and sex-specific growth charts, ideally with guidance from a healthcare professional.
Age doesn't change the BMI formula itself — BMI is always weight divided by height squared. What changes is how the result is interpreted: for adults (18 and over), the standard BMI categories on this page apply, but for children and teenagers, the same BMI number is interpreted differently using age- and sex-specific growth charts rather than the adult ranges.
BMI is calculated only from height and weight. Body fat percentage measures the actual proportion of fat in your body and requires different measurement methods, so the two numbers can tell different stories for the same person.
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