The correct answer is that a properly sized blood pressure cuff should cover about half of the upper arm, which equates to approximately 80% of the circumference to ensure accurate measurements.
A properly sized blood pressure cuff should not cover the entire upper arm, the forearm, nor the wrist when conducting a routine blood pressure measurement. Instead, the appropriate cuff size should cover roughly 80% of the circumference of the upper arm. This translates to about half of the upper arm, ensuring an accurate measurement. A cuff that is too small or too large may yield inaccurate blood pressure readings. Blood flow is detected just below the cuff, and corresponding pressures are captured and transmitted to a mercury-filled manometer or another blood pressure monitoring device.