How to Calculate BMI by Height and Weight

BMI stands for Body Mass Index. It is a measurement using height and weight to calculate about how much body fat you have. Men, women and children can use BMI to assess ideal weight. The goal is to have a BMI between 18.5 and 24.9. Although it is a good measurement for the general public, it does not take into account your fitness level. It is possible that a physically fit person (bodybuilder or athlete) might have a BMI that puts him in the overweight category.

Instructions

• 1

  Measure your current height. You must have an accurate height in feet and inches. If you use a BMI calculator like one found at the National Heart Lung and Blood Institute's website, you would simply plug in your height into the calculator. If you use a BMI table, you would locate your height in inches across the left side of the table. For manual calculations, convert your height to inches. A five feet person is 60 inches tall.

• 2

  Weigh yourself. To get an accurate weight, use a scale that has been recently calibrated. Take off your shoes and do not wear heavy clothing. Get weighed at a doctor's office by an objective party for accuracy if you would like. Your accurate weight in pounds can be entered into a BMI calculator or located across the top of a BMI table. For manual calculations, know your weight in pounds.

• 3

  Calculate your BMI. You can enter your height and weight into a BMI calculator to get a BMI "number." You can also use a BMI table (http://www.nhlbi.nih.gov/guidelines/obesity/bmi_tbl.htm). To use a table, find your height in inches down the left side of the table (vertical axis) and your weight in pounds across the table (horizontal axis). Follow the place where the two numbers intersect on the table and look at the top at your corresponding BMI number.

  To calculate your BMI manually, take your weight in pounds and multiply by 703. Now take that answer and divide by your height (inches). Take that answer and divide by your height (inches) again for a final number. For example, a person who is 165 pounds and is five feet and seven inches tall would multiply 165 by 703 to get 115,995. Then divide this total number by 67 to get 1,731.2686. Then divide this answer by 67 again to get 25.8. The BMI would be about 26.

• 4

  Compare your BMI number to suggested ranges. According to the National Heart Lung and Blood Institute, a BMI of less than 18.5 is considered too low a weight. A BMI between the ranges of 18.5 to 24.9 is considered a normal weight. A BMI of 25.9 to 29.9 is overweight, while a BMI greater than 30 is considered obese.

• 5

  Understand what your BMI calculation means. The higher the BMI, the greater your risks of weight-related issues like diabetes or high blood pressure. Reducing the amount of body fat you carry through exercise and diet is recommended. However, if you work out all the time and have developed significant muscle mass, this BMI number might be somewhat misleading.