Blood pressure measurement with apps, smartwatches, fitness trackers and similar devices

Cuffless blood pressure measurement

More and more devices are coming onto the market that claim to measure blood pressure without the usual cuff. These devices look like a watch or a wristband. Instead of putting on a device and watching the cuff inflate, blood pressure can be measured almost effortlessly. People usually wear the device all day, so they always have the option to measure their blood pressure, which can give a very detailed picture of their blood pressure over time.

How does the measurement work?

The devices measure and analyze the pulse wave coming from the heart. What they determine is the pulse transit time (PTT). The higher the blood pressure, the stiffer the vessels and the faster the pulse wave travels. You can imagine it like a soccer ball that rolls more easily when its pumped up firmly. With this method you cant directly measure the blood pressure itself, but you can detect changes in blood pressure. Thats why these devices always need reference measurements. This technique has been researched for many years. Alternatively, photoplethysmographic (PPG) signals are used the OptiBP app, for example, uses this approach.

Unlike conventional cuff devices, with these new devices it doesnt matter whether the measurement point is at heart level or not. You only need to sit or stand still for the measurement. Many devices also have a sensor that detects movement and either flags it as an error or discards the measurement.

Are the measurement results accurate?

We need to distinguish two broad categories of these devices. There are very simple devices on the market that are usually quite cheap. They offer a blood pressure reading but are not certified as medical devices. The results are well basically useless. Thats a novelty feature that determines blood pressure about as reliably as rolling a die.

But there are also devices that are approved as medical devices. In those cases the measurement accuracy has been validated. Examples include Samsungs Galaxy Watch models, the Aktiia band (now called Hilo), or the OptiBP app.

Usually the device or app must be calibrated to the individual user. That means you measure with a standard cuff device and at the same time with the new device. Usually two or three paired measurements are needed. This calibration must be repeated regularly typically every month. In the meantime, you can conveniently measure without a cuff at any time.

How well does this work in practice?

Unfortunately we have to temper expectations. We tested a Samsung Galaxy Watch, the Hilo (formerly Aktiia) band and the OptiBP app in detail.

The good news: it actually works! You do see realistic readings and the normal day-to-day fluctuations are visible.

However, the measurements tend to stay close to the calibration values. In our comparison we tested the Aktiia (now Hilo) band against guideline-compliant home measurements over a week using a standard cuff device. The differences were 15 mmHg systolic and 4 mmHg diastolic. We did not run such an extensive test series with the Galaxy Watch 3, but in direct comparisons between the cuff device and the watch the differences were sometimes substantial. The OptiBP app showed deviations up to 12 mmHg systolic and 15 mmHg diastolic; after recalibration the diastolic deviation at least decreased significantly.

The standards DIN EN ISO 81060-3 or DIN EN ISO 81060-5 are intended for validating devices with continuous measurements. Since these devices are worn during everyday activities, they must provide accurate measurements even during movement and be able to reliably track blood pressure over longer periods. However, Samsung and the manufacturer of Aktiia (now Hilo) used the DIN EN ISO 81060-2 standard for validation.

To explain simply: in a device test under DIN EN ISO 81060-2 the blood pressure is measured manually as a reference and alternately with the device multiple times. During this sequence the values are usually quite close together because no activities are taking place and the measurements happen close in time. That is sufficient for a cuff device. But cuffless devices are calibrated. All they would need to do to pass that test is repeatedly display the calibration value unchanged and they would likely pass. Thats totally unsuitable for making a statement about real measurement quality.

Manufacturers like to cite studies that are supposed to prove accuracy. You have to look at those studies closely. For example, weve seen a study where the test measurements were done only shortly after calibration. That doesnt say much about how accurate the results are in everyday use.

Study

An international review in JAMA Cardiology (April 2025) comes to a sobering conclusion: so far no cuffless blood pressure device has passed the strict accuracy tests required for traditional upper-arm cuff devices. Most models must first be set using a conventional cuff and can then deviate from the true value by about 510 mmHg especially when you move, exercise, or sleep at night. Factors such as skin pigmentation, obesity, arterial stiffness, heart rhythm disorders (arrhythmias), or tremor also affect the optical sensors (PPG) in these devices and increase measurement errors. Such inaccuracies raise the risk of dosing blood pressure medication too high or too low. Experts therefore recommend for now using only devices that have been proven accurate in independent tests and treating cuffless models as an interesting but not yet mature supplement.

Result

If high values are recorded during calibration, those high values will also appear in everyday use. If the calibration values are in the normal range, everyday readings will also tend to be normal. Thats still too much guesswork, estimation, or chance to be truly useful. Especially in people with high blood pressure, readings can vary more than a cuffless devices calibration allows for.

In practice we often avoid the Aktiia (now Hilo) band because its uncomfortable to wear and, due to lack of waterproofing, often has to be taken off and put back on. And the measurements you get are of little practical value.

The Galaxy Watch is a good smartwatch overall. But because the measurements seemed unreliable, we stopped checking regularly the measurement function basically fell out of use. When the watch then asked to be recalibrated every month, we turned the function off rather than do the monthly calibration for little benefit.

The OptiBP app would be convenient because you always have it with you. However, the ongoing subscription costs are too high given that the values are still too unreliable.

Conclusion July 2025: Unfortunately, for patients with high blood pressure theres still no substitute for the cuff.

In June 2025 the IEEE EMBS Symposia: Recent Advances in Cuffless Blood Pressure took place, where the current status was discussed. We attended. It became clear that the technology is not yet ready for broad clinical use as a replacement for traditional methods. The main reasons are fundamental challenges in validating accuracy, especially in tracking blood pressure changes (trend tracking) over different time periods. Experts emphasized the need for strict, independent validation studies that go beyond isolated accuracy points and demonstrate clinical relevance and improved patient outcomes. There is a clear need for medical approval for devices that report blood pressure values. Clinical use is therefore only conceivable after these strict requirements are met, clinical benefit is proven in outcome studies, and clear usage guidelines are established.

Hybrid between a blood pressure watch and a smartwatch: Huawei Watch D

Huaweis Huawei Watch D is a full smartwatch that also offers blood pressure measurement using an integrated cuff. Because it measures with a cuff similar to a standard device the concerns mentioned above do not apply. More information in our article on blood pressure watches.

Blood pressure measurement with a camera

There are also providers who claim to determine some vital signs, including blood pressure, from a 60-second video of your face. Thats very innovative, so we looked at the solution from Binah.ai. However, in our test the blood pressure determined was about 15 mmHg off from the cuff device. Disappointing, but that was the situation at the end of 2023. Maybe results will improve in the future.

Sources:

This article comes from BloodPressureDB – the leading app since 2011 that helps hundreds of thousands monitor their blood pressure every day. Our content is based on carefully researched, evidence-based data and is continuously updated (as of 02/2026).

Author Horst Klier has been intensively involved with high blood pressure since 2002 initially from personal experience and, since 2009, as the developer of BloodPressureDB. Thanks to his app and specialist platform used by millions as well as numerous publications, he is now regarded as a recognised blood pressure expert. As the author of several health guides and professional articles, he makes complex information understandable and practical.