BMI Process

Several different parameters determine your level of fitness--body fat percentage, flexibility, aerobic capacity, muscle strength, muscle endurance and BMI. Body mass index (BMI) is a measure of fatness that's a relationship of your height to your weight. It's most utilized by doctors to determine your risks for health complications, and there is a process involved with determining it.

Weight

In order to figure out your BMI, get an accurate reading of your weight in pounds or kilograms. Step onto the scale first thing in the morning on an empty stomach, after you have used the bathroom. When you are getting your weight, wear as little clothing as possible. After you determine your weight, multiply it by .4536 to get kilograms. As an example, if you weigh 200 lbs., your weight is 90.7 kg.

Height

Your height must be determined in pounds and meters squared. Stand with your back against a wall or the inside of an open doorway. Place a small tick mark on the wall at the top of your head. Measure this distance with a tape measure and record your height in inches. Multiply it by .0254 to get meters. As an example, if you are 6 feet 4 inches tall, your height is 76 inches and 1.93 meters. Once you square these numbers, you get 5,776 inches and 3.72 meters.

Equations

The metric system equation for BMI is weight in kilograms divided by height in meters squared. If you use the numbers from the above sections, the equation looks like this: 90.7/3.72 = 24.38.

The English system equation is weight in pounds divided by height in inches squared times 703. If you use the same numbers for an example, the equation looks like this: 200/5776 x 703 = 24.34.

Results

Once you have determined your body mass index, you can refer to a chart to see where you land. If your BMI is less than 18.5, you are considered underweight. If you are between 18.5 and 24.9, you're considered normal range. If you are 25 to 29.9, you are considered overweight. If your BMI is over 30, you are considered obese. If you follow the above example, a BMI of 24.34 or 24.36 falls just into the normal range.