How to Size a Blood Pressure Cuff
Measure the girth of the middle area of your upper arm, where the cuff is normally placed. Ask another person to hold the tape measure around your arm for a more accurate result.
Determine if the length and width of the blood-pressure cuff are right for your middle upper arm. It is commonly believed that, if you are able to close the cuff around the arm, it is the right size. This is wrong--the appropriate size is mainly determined by the length and width of an inflated cuff. The general rule is that, if the girth of the arm is 33 cm (13"), a larger-sized cuff should be used instead of the standard variety.
Before you let a nurse or any healthcare professional take your blood pressure, inform them of the measurement of your arm. This way, they can provide a cuff of the appropriate size to ensure an accurate reading.
Find out which of the specific cuff sizes is correct for your arm: the adult standard size, the large adult size or the adult “thigh” cuff size. An adult-standard-size cuff is suited to an individual with an upper arm of 27 to 34 cm (up to 13.38"). The \large adult-sized cuff fits plus-sized individuals with an arm girth of 35 to 44 cm (13.7" to 17.3"). Adult “thigh”-sized cuffs are suited to obese individuals or those with a very large arm circumference ranging from 45 to 52 cm (17.7" to 20.4").