BMI Calculator – Calculate Your Body Mass Index Online
Calculate your Body Mass Index instantly using your height and weight. Understand your BMI category and estimated healthy weight range.
Enter your measurements
Your BMI result
Enter your height and weight to calculate your BMI.
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About the BMI Calculator
The BMI Calculator estimates your Body Mass Index (BMI) using your height and weight. BMI is a commonly used screening measurement for categorizing weight status in adults.
Enter your measurements in either metric or imperial units. The calculator converts the measurements when necessary, calculates your BMI, identifies the corresponding BMI category, and estimates the weight range associated with a BMI of 18.5 to 24.9.
BMI is a screening tool rather than a complete assessment of health. It does not directly measure body fat and may not accurately represent health status for athletes, highly muscular people, older adults, children, or pregnant people.
BMI Calculator Features & Attributes
Calculate BMI using centimeters and kilograms.
Calculate BMI using feet, inches, and pounds.
See whether the calculated BMI falls into an underweight, healthy, overweight, or obesity category.
Estimate the weight corresponding to a BMI between 18.5 and 24.9.
Previous calculations are saved locally in your browser.
Works across desktops, tablets, and smartphones.
Calculations happen directly in your browser.
Uses semantic HTML, labels, keyboard-friendly controls, and live result announcements.
BMI Formulas
Metric BMI Formula
BMI = weight (kg) ÷ height² (m²)
Example: If your weight is 70 kg and your height is 1.75 m:
BMI = 70 ÷ (1.75 × 1.75) = 22.86
Imperial BMI Formula
BMI = [weight (lb) × 703] ÷ height² (in²)
Healthy Weight Formula
For an adult BMI range of 18.5–24.9:
Minimum healthy weight = 18.5 × height²
Maximum healthy weight = 24.9 × height²
BMI Results & Categories
For adults, BMI is commonly interpreted using the following categories:
- Below 18.5: Underweight
- 18.5–24.9: Healthy weight
- 25.0–29.9: Overweight
- 30.0 or higher: Obesity
These categories are general screening ranges. A BMI result should be interpreted alongside other health information rather than used as a standalone diagnosis.
How to Calculate BMI Step by Step
- Measure your weight. Record your weight in kilograms or pounds.
- Measure your height. Record your height in centimeters or feet and inches.
- Convert units if necessary. Metric BMI requires height in meters and weight in kilograms.
- Square your height. Multiply your height in meters by itself.
- Divide weight by height squared. This gives your BMI.
- Interpret the result. Compare your BMI with the standard adult BMI categories.
Example Problem
Suppose a person weighs 70 kg and is 175 cm tall.
175 cm = 1.75 m
BMI = 70 ÷ (1.75 × 1.75)
BMI = 70 ÷ 3.0625
BMI ≈ 22.86
A BMI of approximately 22.86 falls within the commonly used healthy-weight BMI category for adults.
Calculation History
Your recent BMI calculations are stored locally in this browser. They are not sent to a server by this calculator.
Frequently Asked Questions
What is BMI?
BMI stands for Body Mass Index. It is a screening measurement calculated from a person's weight and height.
What is the BMI formula?
For metric measurements, BMI equals weight in kilograms divided by height in meters squared. For imperial measurements, BMI equals weight in pounds multiplied by 703 and divided by height in inches squared.
What is a healthy BMI?
For adults, a BMI between 18.5 and 24.9 is commonly classified as the healthy-weight range.
Is BMI a perfect measure of health?
No. BMI is a screening measure. It does not directly measure body fat and does not account for muscle mass, fat distribution, age, or several other factors.
How is BMI calculated?
BMI is calculated by dividing body weight by height squared, using the appropriate measurement system.
Can children use this BMI calculator?
Adult BMI categories should not be used to interpret BMI in children and teenagers. Their BMI is generally interpreted using age- and sex-specific growth charts.
Can BMI be used during pregnancy?
BMI is not used in the same way to assess weight status during pregnancy. Pregnant people should discuss weight and health measurements with an appropriate healthcare professional.
Does a high BMI always mean poor health?
Not necessarily. BMI does not distinguish between muscle, bone, and fat. For example, someone with substantial muscle mass may have a high BMI without having excessive body fat.
Important Note
This BMI calculator is intended for general informational and educational purposes. BMI is a screening measurement and is not a medical diagnosis. If you have concerns about your weight, nutrition, or health, consider speaking with a qualified healthcare professional.