How to Choose the Correct Blood Pressure Cuff Size

Cuff size is one of the most overlooked causes of inaccurate blood pressure readings. A monitor can be perfectly accurate and still give misleading results if the cuff does not fit the arm. Checking takes one minute and a tape measure.

Why cuff size matters

The monitor works by squeezing the artery in the upper arm with an inflatable bladder inside the cuff. For the pressure to be transmitted evenly, the bladder must cover enough of the arm.

• Too small: the cuff has to inflate to a higher pressure to compress the artery, so the reading is higher than your true blood pressure. This could lead to a mistaken impression of high blood pressure.
• Too large: the reading may be lower than your true pressure, which could hide a problem.

How to measure your arm

1. Remove any clothing from your upper arm.
2. Let your arm hang relaxed at your side.
3. Find the midpoint between the bony tip of your shoulder and the point of your elbow.
4. Wrap a flexible tape measure around the arm at that midpoint. It should be snug but not pulled tight.
5. Note the circumference in centimeters or inches.

If you do not have a tape measure, use a piece of string and measure it against a ruler. Ask someone to help if you find it awkward.

Matching your measurement to a cuff

Every cuff states the range of arm circumferences it fits, usually printed on the cuff itself and in the product details. Size names such as “standard” or “large” are not consistent between manufacturers, so always go by the numbers.

As an example, the cuff supplied with our Automatic Upper Arm Blood Pressure Monitor fits arms of 22 to 32 cm, and our Upper Arm Cuff, Large fits 32 to 42 cm.

If your measurement falls outside the ranges available for a monitor, look for a model that offers a suitable size, and ask your doctor or pharmacist for advice.

Cuffs are not interchangeable

A cuff must be compatible with the monitor. Connectors and the monitor’s calculations are designed for specific cuffs. Use only the cuffs the manufacturer specifies for your model.

Checking the fit each time

• Index and range markings: many cuffs have an index line that should fall within a marked range when the cuff is wrapped. If it does not, the cuff is the wrong size.
• Position: the lower edge should sit about an inch above the elbow crease, with the artery marker aligned as the instructions show.
• Snugness: you should be able to slip two fingertips under the edge. If the cuff slides down, it is too loose.
• Bare skin: never wrap the cuff over a sleeve.

Arm shape

Upper arms that are strongly cone-shaped, wider near the shoulder than the elbow, can be hard to fit with a standard rectangular cuff. If the cuff gaps or slips, speak to your doctor. A different cuff design, or in some cases a validated wrist monitor used with careful technique, may be suggested.

When to re-measure

• After significant weight loss or gain
• After a change in muscle bulk
• When buying a new monitor
• If readings change unexpectedly without another explanation

Children and small adults

Small arms need small cuffs, and children’s blood pressure should be measured with equipment and guidance from a healthcare professional.

Wrist monitors

Wrist devices also have a stated range of wrist circumferences. Measure your wrist and check before buying.

Caring for the cuff

• Wipe with a damp cloth; do not machine wash unless the instructions allow.
• Avoid sharp folds in the bladder and tube.
• Replace a cuff that is cracked, leaking or no longer fastens securely.

Questions to ask

• What is my arm circumference?
• Does the cuff’s printed range include it?
• Is this cuff made for my monitor?
• Has my healthcare team seen me fit it?

The bottom line

Measure your arm, match the numbers and check the fit every time. The right cuff is as important as the monitor itself. Find monitors and replacement cuffs in our heart and blood pressure department.

Sources

1. Centers for Disease Control and Prevention. Measuring Your Blood Pressure.
2. British Heart Foundation. How to measure your blood pressure at home.
3. American Medical Association. US Blood Pressure Validated Device Listing.
4. American Heart Association. Understanding Blood Pressure Readings.