How to Calculate Your BMI Online
Body Mass Index (BMI) is one of the most widely used screening tools to categorize a person's weight relative to their height. While it doesn't measure body fat directly, research has shown that BMI correlates with more direct measures of body fat and can indicate potential health risks.
- Choose your unit system: Click "Metric" to use kilograms and centimeters, or "Imperial" to use pounds, feet, and inches.
- Enter your height and weight: Type your current height and weight into the input fields.
- Click "Calculate BMI": Your BMI value, category (Underweight, Normal, Overweight, or Obese), and healthy weight range will appear instantly.
Understanding BMI Categories
The World Health Organization (WHO) defines the following BMI categories for adults:
| Category | BMI Range | Health Risk |
|---|---|---|
| Underweight | Below 18.5 | Possible nutritional deficiency |
| Normal weight | 18.5 – 24.9 | Low risk |
| Overweight | 25.0 – 29.9 | Moderate risk |
| Obese | 30.0 and above | High risk |
Looking for other health and financial calculators? Try our Age Calculator, EMI Calculator, or Percentage Calculator.
Frequently Asked Questions
What is a healthy BMI range?
A BMI between 18.5 and 24.9 is generally considered healthy for most adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese.
Is BMI accurate for athletes?
BMI may overestimate body fat in athletes and people with muscular builds because it doesn't distinguish between muscle mass and fat mass. For a more complete picture, consider additional measurements like body fat percentage.
How is BMI calculated?
BMI is calculated by dividing your weight in kilograms by the square of your height in meters: BMI = weight (kg) ÷ height² (m²). Our calculator handles unit conversions automatically if you use imperial units.
Does BMI apply to children?
For children and teenagers, BMI is interpreted differently using age- and sex-specific percentiles. This calculator is designed for adults aged 18 and over.