Upper arm cuffs win on accuracy and are the standard recommendation for home monitoring; wrist cuffs are a backup for fit or comfort problems and are unforgiving about positioning.
The arm cuff reads at the brachial artery, the same site clinicians use, while the wrist's smaller vessels and extreme sensitivity to position (it must sit exactly at heart level) make wrist readings easier to get wrong. The legitimate wrist-cuff cases: an upper arm cuff that does not fit, causes pain, or is impractical because of mobility or injury. Whatever you buy, validation is the step most people skip and should not: take the device to an appointment and compare it against the clinic's reading. Then technique does the rest: cuff sized to your arm (an undersized cuff reads falsely high), 5 quiet minutes first, back supported, feet flat, arm supported at heart level, and no caffeine, exercise, or smoking in the 30 minutes prior. A modest validated arm cuff used correctly outperforms a premium wrist device used casually.
What to do
Common questions
Wrist vs arm blood pressure cuff: which is better?
Upper arm cuff monitors are the better choice, and they are what clinicians recommend for home monitoring, for a simple reason: they measure at the brachial artery, the same spot your doctor uses, and their readings are consistently more reliable. Wrist monitors measure at a smaller artery where pressure naturally differs from the upper arm, and they are extremely position-sensitive: unless your wrist is held exactly at heart level with your elbow supported, the reading skews, sometimes by a lot. Cleveland Clinic's guidance is that wrist monitors are appropriate only when upper arm cuffs do not fit well or cause pain, which covers people with very large arms, limited mobility, or certain injuries. Whichever device you use, two checks matter more than the device. First, get it validated: bring it to a clinic appointment and compare its readings against the office measurement. Second, fit and technique: the cuff must match your arm size (too small reads high), and you should sit quietly for 5 minutes, back supported, feet flat, arm supported at heart level, no caffeine or smoking in the 30 minutes before. A cheap validated arm cuff with good technique beats an expensive wrist device used loosely every time.