It is no secret that obesity is on the rise in the United States. One way to assess weight status is through body mass index, or BMI. This calculation is a ratio of weight to height. It is a roughly associated with body fat, but does not take into account differences in body composition. A BMI score greater than 25 indicates overweight and a score of greater than 30 indicates obesity. With each one-point increase in BMI over 25, risks of developing a chronic disease like heart disease increase.
Calculating Body Mass Index
Step 1
Measure your weight with the scale. Use the kilogram setting if available so the calculations you make later will be easier. Record the number on a piece of paper.
Step 2
Stand with your heels, head and back against a wall. Have someone mark a spot on the wall corresponding to the tallest point of the top of your head. Using the measuring stick, determine the height of the spot in inches or centimeters, depending on the measuring stick. Record your height on a piece of paper.
Step 3
Calculate your body mass index using one of two formulas. You can determine your BMI by using either inches and pounds or kilograms and meters. If you are going to use inches and pounds, the formula is weight (lb) / [height (in) x height (in)] x 703. If you use kilograms and meters, you may need to make a few conversions first. To convert inches into meters, multiply your height in inches by 0.254. To convert pounds into kilograms, divide your weight in pounds by 2.2. The formula for BMI in this format is weight (kg) / [height (m) x height (m)].
Step 4
Calculate your BMI using a website if you don't have a calculator handy or don't feel like doing the math. The National Heart Lung and Blood Institute, NHLBI, at the National Institutes of Health provides a tool at http://www.nhlbisupport.com/bmi/.
Step 5
Look up a BMI table as an alternative to using the calculators. The NHLBI offers this tool as a quick guide. Find your height in inches in the column on the left, find your height in that row and your BMI is at the top of the column where your height and weight meet.
Things You'll Need
- Scale
- Measuring Stick
- Someone to assist with height measurement
- Calculator
- Pencil
- Paper
- Computer (optional)
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