BMI Calculator
Estimate adult Body Mass Index (BMI) from height and weight. Free metric and imperial BMI calculator with standard adult categories.
Adult BMI categories
| Category | BMI range |
|---|---|
| Underweight | < 18.5 |
| Healthy weight | 18.5 - 24.9 |
| Overweight | 25 - 29.9 |
| Obesity Class I | 30 - 34.9 |
| Obesity Class II | 35 - 39.9 |
| Obesity Class III | ≥ 40 |
About BMI Calculator
Estimate adult Body Mass Index from height and weight using metric or imperial units. Review the calculated BMI and standard adult category ranges. BMI is a screening measure rather than a diagnosis and does not distinguish muscle from fat; consult a health professional for individual guidance.
How to Use BMI Calculator
- 1
Select your preferred unit system: Metric (kg/cm) or Imperial (lbs/ft).
- 2
Enter your weight in the weight input field.
- 3
Enter your height in the height input field.
- 4
Click "Calculate BMI" to see your results.
- 5
Read the adult BMI category shown with your result; this screening measure is not a diagnosis.
What Is BMI Calculator and Why Use It?
This adult BMI calculator estimates body mass index from height and weight. With metric units, BMI is weight in kilograms divided by height in metres squared. With imperial units, it uses 703 × weight in pounds ÷ height in inches squared. For example, 70 kg at 1.75 m gives a BMI of about 22.9. The table shows the standard adult ranges: below 18.5, 18.5 to under 25, 25 to under 30, and 30 or higher, with obesity classes shown separately. BMI is a screening measure, not a diagnosis, and it cannot distinguish muscle from fat. Children and teens need age-based BMI percentiles; these adult ranges are not intended for them. If a result concerns you, discuss it with a qualified health professional.
Tips for Best Results
- !
BMI is a screening tool, not a diagnostic — athletes with high muscle mass may have higher BMIs.
- !
For adults, the standard healthy-weight range is 18.5 to less than 25; the calculator rounds the displayed result to one decimal place.
- !
Consult a healthcare professional for a comprehensive health assessment beyond BMI.
- !
BMI does not distinguish muscle from fat and should be considered with other information by a health professional.
Common Use Cases
Personal tracking
Compare your own measurements over time, alongside other health information and professional advice.
Appointment preparation
Bring the estimate to a health appointment as one discussion point, not a complete assessment.
Unit conversion
Use either kilograms and centimetres or pounds, feet, and inches without doing the conversion yourself.
Adult screening
Review the standard adult BMI ranges while keeping in mind that individual health needs vary.
Frequently asked questions
Why Use Our BMI Calculator؟
Supports metric and imperial units
Instant BMI calculation
Standard adult BMI categories
BMI range reference table
No sign-in required
Mobile-friendly interface
How Does This Compare?
BMI vs. Body Fat Percentage
Advantages
- +Quick and easy to calculate
- +No special equipment needed
- +Widely used by healthcare providers
- +Correlates with health risks in large populations
Limitations
- −Cannot distinguish muscle from fat
- −May misclassify athletic individuals
- −Does not account for age, sex, or ethnicity
- −Ignores fat distribution patterns
Did You Know?
BMI was developed in the 1830s by Belgian mathematician Adolphe Quetelet.
The formula is the same worldwide: weight (kg) divided by height squared (m²).
BMI is a screening measure and cannot diagnose a health condition on its own.
A BMI result should be interpreted alongside other health information, not by itself.