Can a smartwatch measure blood pressure? What the 2025 guideline says

By Marcus Renshaw ·

A blood pressure number that appears on your wrist with no cuff, no five minutes of sitting still, and no ritual is the number everyone wants. It is also the one the 2025 blood pressure guideline tells you not to rely on. That is not technophobia from a committee that misses the appeal. It is a measurement problem, and it is worth understanding before you trust a watch with a number this consequential.

No consumer smartwatch measures blood pressure accurately enough to diagnose or manage hypertension. The 2025 ACC/AHA guideline says to avoid relying on cuffless devices until they prove their accuracy, and a December 2025 AHA statement notes most were never validated at all. A validated upper arm cuff is still the only home tool worth trusting.

What does the 2025 guideline say about smartwatch blood pressure?

The 2025 ACC/AHA High Blood Pressure guideline, the first full revision since 2017, is direct about it. Its own summary states that reliance on cuffless devices, including smartwatches, for accurate blood pressure measurements should be avoided until these devices demonstrate greater precision and reliability. The companion language goes further: cuffless devices are not recommended for the diagnosis or management of high blood pressure in adults.

That sits inside a guideline that otherwise pushes hard toward measuring at home. The same document keeps the hypertension threshold at 130/80, and it recommends confirming a diagnosis with out-of-office readings, leaning toward home monitoring over a 24 hour ambulatory study as the practical choice. So the guideline is not anti-home-measurement. It is the opposite. It wants you measuring at home, on a device that actually works, and it singles out the wrist worn optical kind as the one to keep off the job.

The distinction it is drawing is between the cuff and everything trying to replace the cuff. A validated upper arm monitor and a smartwatch are not two points on a quality spectrum. They measure different physical things, and only one of them measures the thing you care about.

Why can’t an optical sensor read blood pressure like a cuff?

A cuff measures pressure. It inflates against your artery and reads the pressure at which blood flow starts and stops, which is, definitionally, your blood pressure. That is oscillometry, and it is why a validated cuff lands within a few mmHg of a clinical device.

A smartwatch has no cuff, so it cannot do that. Most use an optical sensor: a green light on the back of the watch reads how much light your skin absorbs as blood pulses through, and software estimates a pressure from the shape and timing of that pulse. A December 2025 AHA scientific statement on these devices is blunt about the limits. The estimate drifts with arm position, skin tone, and how recently the device was calibrated. The models were mostly built and tested on people sitting still, so they have not been validated for the states you actually live in: during exercise, during sleep, through daily activity, or after taking a medication that moves your pressure.

The statement puts a number on the wider problem. Up to 80 percent of all blood pressure devices sold globally have never undergone formal validation testing, and cuffless devices validate at even lower rates. Its own summary of the field is that the speed of commercialization has outpaced the science. That is a strong sentence to find in an AHA document, and it is the honest state of play.

But some watches now show a blood pressure number. What about those?

Some do, and the way they get there proves the point rather than solving it. Samsung’s blood pressure feature rolled out on its watches in the US in April 2026, and the fine print is the interesting part. It ships as a wellness feature, not a medical device, and it is not cleared by the FDA for diagnosing or managing hypertension. More telling, it requires you to calibrate it against a traditional cuff, and to recalibrate every 28 days.

Read that mechanism through and the value collapses. The watch is not measuring your pressure. It is estimating a change from a cuff reading you fed it, and that reference goes stale in a month. You still need the cuff. The watch just adds an estimate layer on top of it that decays and has to be re-anchored. For a spot curiosity that is fine. For a number you make decisions on, you have added drift and complexity to a measurement the cuff already made correctly on its own.

None of this means the technology is worthless or permanently stuck. The AHA statement calls it promising, and a cuffless device that a reader could trust would be genuinely useful. It means the validation is not there yet, and a health decision is the wrong place to front the science credit.

What actually counts as a validated home monitor?

A validated automated upper arm oscillometric cuff. That is the whole answer, and the word doing the work is validated, which is not the same as available for sale or well reviewed.

Validation means the specific model was tested against a reference standard in a formal protocol and passed. Two independent lists let you check before you buy. In the US, the Blood Pressure Validated Device Listing at validatebp.org is an AMA supported program whose devices are reviewed by an independent physician committee. Internationally, STRIDE BP publishes validated device lists vetted by its scientific board. If your monitor is not on one of them, you do not actually know it is accurate, however confident the number on the screen looks.

Prefer the upper arm over the wrist even among cuffs. Wrist cuffs are more sensitive to position, since the wrist has to be held at heart level for the reading to mean anything, and fewer of them are validated. An upper arm cuff on a bare arm, resting at heart level, removes that variable. Then the technique carries the rest: the fifteen seconds before you press start are where most home error actually comes from, cuff or no cuff.

Where this leaves a self-experimenter

Here the clinical guideline and the optimization case point the same way, which is not always true. The guideline says do not diagnose off a wrist number. The self-experimenter has a second, sharper reason: the whole value of home tracking is the trend, and a drifting instrument destroys a trend specifically.

If you are running a protocol, you are not taking one reading to answer one question. You are watching a line over months to see what your stack does to it. Testosterone or a SERM nudges pressure up over time through rising hematocrit. Tadalafil and meaningful weight loss on a GLP-1 pull it down. When three compounds are moving the same number, the only way to attribute the change is a stable, accurate baseline you can trust from one month to the next. A device that re-references itself against a cuff every 28 days cannot give you that. Any real drift in your pressure and any drift in the watch’s calibration are now tangled in the same line, and you cannot separate them after the fact.

So the answer is not that wrist tech is beneath a serious tracker. It is that a serious tracker needs the one thing these devices cannot yet promise, which is that a difference in the number reflects a difference in you. Buy the validated cuff, put it next to the coffee machine, and let the watch count your steps. When a cuffless device finally clears the validation bar the AHA is holding it to, it will earn a place. It has not yet.

If you have been treating a smartwatch reading as your blood pressure, take one week of mornings and evenings on a validated cuff alongside it. The gap between the two is the measurement problem the guideline is pointing at, made concrete on your own arm.

FAQ

Can a smartwatch measure blood pressure accurately?

Not accurately enough to rely on. The 2025 ACC/AHA guideline says reliance on cuffless devices including smartwatches should be avoided until they demonstrate greater precision, and a December 2025 AHA statement notes most cuffless devices are never validated. Smartwatches estimate pressure optically rather than measuring it with a cuff, and the estimate drifts with position, skin tone, and calibration age.

Does the 2025 blood pressure guideline allow smartwatch readings?

No. It recommends against relying on cuffless devices for accurate blood pressure and says they are not recommended for diagnosing or managing high blood pressure. The same guideline strongly endorses home monitoring, but on a validated upper arm cuff, and it prefers out-of-office readings to confirm a diagnosis.

Why does a smartwatch need to be calibrated with a cuff?

Because it does not measure pressure directly. An optical sensor estimates pressure from the shape of your pulse, and that estimate has to be anchored to a real cuff reading. Samsung’s feature requires recalibration every 28 days, which means you still need a cuff and the watch only tracks an estimated change from it that goes stale.

What is the most accurate way to measure blood pressure at home?

A validated automated upper arm oscillometric cuff, used with correct technique: back supported, feet flat, bare arm at heart level, five minutes of rest, two readings a minute apart, morning and evening. Check that your specific model appears on validatebp.org or the STRIDE BP list before trusting it.

Are wrist blood pressure monitors accurate?

Cuff based wrist monitors can be accurate if validated, but they are more error prone than upper arm cuffs because the wrist must be held exactly at heart level, and fewer models are validated. An upper arm cuff removes that positioning variable. Optical wrist estimates on a smartwatch are a separate thing and are not reliable for diagnosis.

How do I know if my blood pressure monitor is validated?

Check the model against an independent list. In the US, validatebp.org maintains the Blood Pressure Validated Device Listing, reviewed by a physician committee. STRIDE BP maintains an international list. If your device is not on either, it has not passed a formal accuracy protocol, regardless of its ratings or price.

Will cuffless blood pressure ever be reliable?

Possibly. The December 2025 AHA statement calls the technology promising while noting that commercialization has outpaced the science and that current devices are not validated for real world use. If a cuffless device passes formal validation against a reference standard, it will earn a role. Until then it is not the tool for a health decision.

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