The World Health Organization does not recommend wrist blood pressure monitors for clinical use. In its technical specifications for blood pressure devices, the WHO states that wrist devices “may give inaccurate measurements” and notes that “most guidelines do not recommend their use.” That said, wrist monitors aren’t useless. For certain people and situations, they can be a practical option, but only with proper technique and an understanding of their limitations.
Why the WHO Discourages Wrist Monitors
The WHO’s concern comes down to two problems. First, blood pressure readings from the wrist are not equivalent to readings from the upper arm. Systolic and diastolic pressure vary substantially at different points in the arterial system, so a measurement taken at the radial artery (on the wrist) may not match what you’d get from the brachial artery (inside the elbow). Second, wrist monitors are highly sensitive to arm position. If your wrist isn’t held exactly at heart level during the reading, the hydrostatic pressure from gravity skews the result.
The WHO also flags that many wrist devices on the market have not been independently validated for accuracy, which is a separate issue from whether the technology can work in principle. A device that hasn’t passed a recognized validation protocol is essentially untested, regardless of what it costs or what its packaging claims.
How Much Accuracy Do You Lose?
A study of 253 cardiology patients compared wrist readings to standard upper arm measurements. The wrist device read an average of 16 mmHg higher for systolic pressure and 6 mmHg higher for diastolic. That’s a significant gap. To put it in practical terms, a difference of that size could mean the wrist monitor says you have high blood pressure when you don’t, or it could push a borderline reading into a range that triggers unnecessary worry or medication changes.
Only about 40% of patients in that study had wrist readings close enough to upper arm readings to be considered reliable. For systolic pressure specifically, 43% of patients had readings that differed by more than 20 mmHg, a margin large enough to change how hypertension is classified. The researchers concluded wrist monitors “cannot compete” with the upper arm standard.
When Wrist Monitors Make Sense
Despite those accuracy concerns, there are situations where a wrist monitor is the better practical choice. The Mayo Clinic and the American Heart Association both acknowledge two groups who may benefit from wrist devices: people with very large upper arms who can’t get a proper cuff fit, and people who’ve had lymph nodes removed from the armpit (common after certain cancer surgeries).
Research on obese patients supports this. One study found that upper arm blood pressure readings in obese individuals were significantly lower than in lean individuals for systolic pressure, likely because a poorly fitting cuff compresses arm tissue unevenly. Wrist readings, by contrast, averaged the same (about 106 mmHg systolic) in both obese and lean groups. When the upper arm cuff can’t fit correctly, it introduces its own errors, and a validated wrist device may actually give you a more consistent number.
How to Get Accurate Wrist Readings
If you use a wrist monitor, positioning is everything. The most common source of error is holding your wrist too low or too high relative to your heart. Even a few inches of difference creates a measurable change in the reading due to gravity’s effect on blood in your arteries.
To get the best result:
- Sit in a chair with your back supported and feet flat on the floor. Don’t cross your legs.
- Place the cuff directly on skin over the radial artery, the spot on your inner wrist where you can feel your pulse. Never measure over clothing.
- Raise your wrist to heart level. Resting your elbow on a table and bending your arm up so your wrist sits at mid-chest height works for most people. Some newer devices include a position sensor that alerts you when your wrist is at the correct height.
- Keep your wrist straight. Bending or flexing the wrist compresses the artery unevenly and produces incorrect readings.
- Stay still and don’t talk during the measurement.
Newer wrist monitors with built-in position sensors can reduce the hydrostatic error to about 4.8 mmHg, which meets the accuracy threshold set by international standards organizations. That’s a meaningful improvement over older devices that offered no positioning guidance, though it still requires you to sit properly and hold still.
What “Validated” Actually Means
Not all wrist monitors are created equal. The key distinction is whether a device has passed an independent validation study. The current international standard is ISO 81060-2:2018, which requires that the average difference between a device and a reference measurement be no greater than 5 mmHg, with a standard deviation no greater than 8 mmHg. STRIDE BP, a major international database of validated blood pressure monitors, lists devices that have passed these protocols.
As of 2024, new validation studies must use this universal standard. Some wrist devices have passed it. For example, the DBP-2242 wrist monitor met all ISO criteria and was recommended for use in adolescents and adults. But many wrist monitors sold online or in pharmacies have never been tested against these benchmarks. Before buying one, check the STRIDE BP database (stridebp.org) to see if your specific model is listed.
Cross-Check With Your Doctor’s Office
If you rely on a wrist monitor at home, the Mayo Clinic recommends bringing it to a healthcare appointment so your care team can compare its readings against a standard upper arm measurement. This tells you whether your particular device, on your particular wrist, gives readings close enough to be useful. If the numbers differ by more than about 10 mmHg diastolic or 20 mmHg systolic, the wrist device isn’t reliable for you personally, even if it’s validated in general.
This cross-check is worth repeating periodically, since changes in weight, medications, or the device’s battery and calibration can shift accuracy over time.