How to Calculate Your BMI Using Your Arm Span

Your body mass index, otherwise known as BMI, is calculated by your weight and height measurements. Your BMI is not a direct indication of weight, but places your body into different categories such as: underweight, normal, overweight, or obese.

Since a persons arms span is approximately the same as their height, this measurement may be used as a fairly reliable means of measuring BMI.

Things You'll Need

• Tape measure
• BMI calculator

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Instructions

• 1

  Stand straight up with your head facing forward, and your arms straight out, parallel to the floor. This ensures the most accurate measurement of your arm span.

• 2

  Measure (in inches) from left fingertip, across torso, ending at right fingertip. This is an approximate measure of your height.

• 3

  Use a scale to weigh yourself, preferably in the morning, without clothing. If you have the time, do a weight measurement every day for three days. Total these three measurements and divide that number by three. This is your weight in pounds.

• 4

  Calculate your BMI with the aid of numerous online calculators for your data, or the following formula: (weight in lbs x 703 ) / (height in inches)².

• 5

  Check your results, which fall into one of four categories. A BMI below 18.5 indicates your body is underweight; 18.5 to 24.9 places your weight within normal range. A BMI of 25 to 29.9 may indicate that your body is over the recommended weight for your height; and a BMI over 30 places your weight into the obese category.