By Mayo Clinic News Network

The in-store blood pressure machines are not accurate enough to make health decisions regarding your blood pressure.

The free blood pressure machines in many grocery stores, drugstores and other locations may have been accurate when first installed. But to stay accurate, they must be maintained and recalibrated. Generally, no information is available regarding the care of these devices. As a result, the reading you get has limited value because it may be incorrect.

In addition, the blood pressure cuffs on these do-it-yourself machines are often too small to get an accurate reading on some people with high blood pressure. To ensure accuracy, the inflatable portion of the cuff should cover at least 80 percent of the upper arm.

It's best to have your blood pressure checked in a medical facility or in a community screening program with trained staff. Before diagnosing or treating high blood pressure, you'll need to have your blood pressure measured in your doctor's office on several separate visits.

If you need to check your blood pressure more frequently, your doctor can instruct you on the best way to monitor your blood pressure at home. Home blood pressure monitoring can be an inexpensive, accurate way to get regular blood pressure readings.

-- Sheldon G. Sheps, M.D.

Source: http://www.mayoclinic.org/diseases-conditions/high-blood-pressure/expert-answers/blood-pressure/faq-20058474/