Wrist blood pressure monitors can be accurate if used exactly as directed. However, according to the American Heart Association, it's best to use a home blood pressure monitor that measures blood pressure in your upper arm. Devices for the upper arm are also easier to check for accuracy than are wrist monitors.
Wrist blood pressure monitors are extremely sensitive to body position. To get an accurate reading when taking your blood pressure with a wrist monitor, your arm and wrist must be at heart level. Even then, blood pressure measurements taken at the wrist are usually higher and less accurate than those taken at your arm. That's because the wrist arteries are narrower and not as deep under your skin as those of the forearm.
Some people can't have their blood pressure measured at the upper arm because they have a very large arm or find blood pressure measurements painful. In these cases, measuring blood pressure at the wrist is acceptable.
It's not uncommon for blood pressure readings taken at home on any type of monitor to be different from those taken at your doctor's office. If you have a wrist blood pressure monitor, it's a good idea to take your monitor to a doctor's appointment. Your doctor can then check your blood pressure with both a standard upper arm monitor and a wrist monitor in the correct position in the same arm to check your wrist blood pressure monitor's accuracy.