Do You Really Have High Blood Pressure or Is Your Cuff Size Wrong?

Your blood pressure reading can tell you a lot about your current health as well as give you an idea of your risk for conditions like heart disease and stroke. However, to be useful, the number you get has to be accurate. You might be surprised at how something as simple as a cuff that’s too tight could throw off a reading.

According to a recent study, using the wrong cuff size when taking your blood pressure can lead to inaccurate readings. If a cuff is too small, the blood pressure reading could be higher than it actually is. If the cuff is too big, the reading can come out lower.

The researchers found that the wrong cuff size can lead to a difference in blood pressure ranging anywhere from 5 to 20 mmHg. Since there are ranges that define what normal blood pressure is versus one that’s too low or too high, even being a few numbers off could have a negative effect on your health.

“An overestimation of blood pressure could potentially result in overtreatment of hypertension, leading to unnecessary adverse effects from medical interventions and increased expenditure on medications,” Junichi Ishigami, MD, PhD, a study author and assistant scientist of epidemiology at the Johns Hopkins Bloomberg School of Public Health, told Verywell.

Ishigami added that underestimating blood pressure can lead to “undertreatment and the occurrence of preventable cardiovascular and kidney complications related to hypertension.”

Here’s what experts say about why cuff size matters for taking a blood pressure reading and what you should know about keeping track of this key health metric.

How Is Blood Pressure Cuff Size Measured?

The right cuff size is based on the circumference of your mid-upper arm, which you can measure at home with a measuring tape.

Although clinical practice guidelines for providers recommend choosing an appropriately sized cuff based on a patient’s arm size before taking a blood pressure measurement, Ishigami said that the key part of the process is often overlooked because there are time constraints or a lack of cuffs that come in different sizes. As a result, a regular adult cuff is often used routinely for all patients.

Ishigami said that for the new study, the team wanted to assess the possible effects of these limitations and practices.

The findings showed that individualized cuff selection is always necessary—simply put, there is no one-size-fits-all when it comes to blood pressure measurement. 

Anika L. Hines, PhD, MPH, an assistant professor of health behavior and policy at the Virginia Commonwealth University School of Medicine, told Verywell that while “using a measuring tape in clinical practice seems less practical,” determining the correct cuff size is an important recommendation to healthcare providers.

What Does a Poor-Fitting Blood Pressure Cuff Feel Like?

Ideally, healthcare providers would have different cuff sizes to accommodate a range of patients, but Hines said that’s not always the case. There are certainly facilities and practices that have limited cuff availability.

“For example, finding cuffs in larger sizes may be difficult for those using automated blood pressure monitors,” Hines said. “Providers may find themselves using entirely different monitors for patients with larger arms, including taking manual blood pressure readings.”

In general, the cuff should not feel uncomfortably tight before it is inflated to take a reading. If it does feel too tight as soon as it’s put on, or you already happen to know what cuff size you’ve used before, Hines said that you can ask the provider whether the cuff being used is the correct size for you.

The cuff should wrap snugly and securely around your arm with just enough space to slide two fingertips underneath.

“If more than two fingertips fit between the patient’s arm and the cuff, it may be too loose,” Hines said. “If you can’t slip two fingertips under the edge of the cuff at all, it may be too tight.”

Ishigami also recommends asking the provider whether the size is correct because figuring out the right size is not something that can be done just by looking at it in an exam room.

How to Get Accurate Blood Pressure Readings at Home

It’s not just at the provider’s office or clinic that the right fit is important: Ishigami said that cuff size also matters when you’re monitoring your blood pressure at home.

“If you are not sure about whether you are using a correct blood pressure cuff for home blood pressure monitoring, bring the blood pressure cuff and ask your doctor,” Ishigami said. “If you are considering purchasing a new blood pressure monitoring device, talk to your doctor before making the actual purchase.”

Once you’ve got the right cuff size, Hines said there are other factors that you should be aware of if you want to get an accurate blood pressure reading at home, including having a validated blood pressure monitor. That means if you’re using the monitor for an older adult, a pregnant person, or a child, then it has to be validated specifically for these uses.

You can ask a provider or pharmacist for advice or recommendations if you’re not sure what kind of home blood pressure monitor to get. You can also check the U.S. Blood Pressure Validated Device Listing to see if the device you have has been validated for clinical accuracy.

Hines said you also need to take two readings at an interval of one minute, then average the two readings to get a good representation of your blood pressure.

A single reading may not accurately reflect your blood pressure—for example, you may have been nervous about doing it on your own the first time, so it could have been a little higher than it usually would be. It’s also important to take your blood pressure at the same time every day, which will give you a better sense of your normal range compared to what you’d see by taking one reading on a single day.

Bottom line: “The same rules apply for good BP measurement at home as in the office,” Hines said.