As stated, BMI compares your weight for your height. In general, as BMI increases, so does the risk for health complications. As you read, keep in mind that BMI is meant to compare the average body type . You want to have a BMI less than 25 in order to decrease your risk for diseases associated with being overweight. A BMI between 18.5 and 24.9 corresponds to a healthy weight. As your weight rises above that level so does your risk for health complications, including high blood pressure, Type 2 diabetes, heart disease, stroke, osteoarthritis, and some cancers.
You can find a BMI calculator on the National Institutes of Health's website at http://www.nih.gov. However, if you would like to learn how to calculate your BMI yourself, the equation is weight in kilograms (kg) divided by height in meters (m) squared.
BMI Equation: Weight (kg) / Height (m) squared
Here's a sample calculation for a person who is 150 pounds and 5 feet 8 inches (68 inches) tall. Try this one for practice and then plug in your measurements in order to calculate your own BMI.
1. Determine weight in kilograms.
Divide pounds by 2.2.
Ex). 150/2.2 = 68.2 kg
2. Determine height in meters squared.
First, determine ht. in cm.
Ex). 68 inches x 2.54 = 172.72 cm.
Next, divide ht. in cm. by 100 to get ht. in meters.
Ex). 172.72/100 = 1.73
Then, square ht. in meters.
Ex). 1.73 x 1.73 = 2.98
3. Divide wt. in kg (68.2) by ht. in meters squared (2.98) = 23
Less than 18.5 = Underweight
18.5-24.9 = Healthy Weight
25-29.9 = Overweight
30-39.9 = Obese
40 and above = Morbidly Obese
The person in the sample calculation has a BMI of 23, which is within the healthy range (18.5-24.9). How about you?
 One of the BMI's downfalls is that it does not take into consideration your body composition, which means that if you happen to be quite muscular, then your BMI may seem falsely high. The BMI assumes that any extra weight you have is fat, not muscle.