A sphygmomanometer or blood pressure meter is a device used to measure blood pressure. Mercury manometers are considered to be the gold standard and are consistently accurate. It consists of an inflatable cuff, a measuring unit (the mercury manometer, or aneroid gauge), and inflation bulb and valve, for manual instruments. The cuff is normally placed smoothly and snugly around an upper arm, at roughly the same vertical height as the heart while the subject is seated with the arm supported.

By observing the mercury in the column while releasing the air pressure with a control valve, one can read the values of the blood pressure in mm Hg. The peak pressure in the arteries during the cardiac cycle is the systolic pressure (normally 120 mm Hg), and the lowest pressure (at the resting phase of the cardiac cycle) is the diastolic pressure (80 mm Hg, normal). A stethoscope is used in the auscultatory method. Systolic pressure (first phase) is identified with the first of the continuous Korotkoff sounds. Diastolic is identified at the moment the Korotkoff sounds disappear (fifth phase).