Blood pressure measurement with app, smartwatch, fitness tracker, and more.

Measuring blood pressure without a cuff

fitness tracker with blood pressure measurement

More and more devices are coming onto the market that can measure blood pressure without the usual cuff. These devices are shaped like a watch or a bracelet. Instead of awkwardly putting on a device and watching the cuff inflate, blood pressure can be determined almost effortlessly. The device is usually worn all day, providing constant measurement opportunities, which offers a perfect overview of one's blood pressure.

How does the measurement work?

The devices measure and analyze the pulse wave that emanates from the heart. The pulse wave transit time (PTT) is determined. The higher the blood pressure, the more tense the vessels are, and the faster the pulse wave travels. One can imagine this like a soccer ball that rolls more easily when it is well inflated. In this way, one cannot determine the blood pressure itself, but can detect a change in blood pressure. Therefore, the devices always require reference measurements. This technology has been researched for many years. Alternatively, photoplethysmographic (PPG) signals are used; for example, the OptiBP app uses this approach.

Unlike conventional cuff-based measuring devices, it is irrelevant whether the measurement point is at heart level with these novel devices. To measure, one simply needs to remain calm. The devices often also have a sensor that detects movements and indicates them as errors or discards the measurement.

Are the measurement results accurate?

One must fundamentally distinguish between two categories of these devices. There are very simple devices in this field, which are usually also very inexpensive. These offer blood pressure measurement but are not certified as medical devices. The results are - well - completely useless. This is a fun feature that determines the actual blood pressure as well as a dice roll.

However, there are also devices that are approved as medical devices. In this case, the measurement accuracy has been validated. Examples include the Galaxy Watch from Samsung, the Aktiia bracelet, or the OptiBP app.

Here, the device or app usually needs to be calibrated to the individual user. This means that one measures with a conventional cuff-based device and simultaneously with the device. Usually, two or three measurements are required. This calibration must be repeated regularly - typically monthly. In the meantime, measurements can be conveniently taken without a cuff at any time.

How well does this work in practice?

Unfortunately, we must temper expectations. We have thoroughly tested both a Samsung Galaxy Watch, the Aktiia bracelet, and the OptiBP app.

The good news: It really works! One actually sees realistic measurement values, and the normal fluctuations in daily blood pressure are clearly visible.

However, the measurements always only fluctuate around the calibration values. In our comparison, we compared the Aktiia bracelet with guideline-compliant home measurements over a week with data from a conventional measuring device. The deviation was 15 mmHg systolic and 4 mmHg diastolic. For the Galaxy Watch 3, we did not conduct such an extensive test series, but in direct comparison with the cuff device and the watch, the differences were sometimes significant. The OptiBP app showed deviations of up to 12 mmHg systolic and 15 mmHg diastolic; after a recalibration, the diastolic deviation at least decreased significantly.

For the validation of devices with continuous measurements, the standard DIN EN ISO 81060-3 is provided. Since the devices are worn during everyday activities, they must allow for accurate measurements even during movement and must be able to monitor blood pressure stably and reliably over longer periods. However, Samsung and the manufacturer of Aktiia used the standard DIN EN ISO 81060-2 for validation.

Manufacturers like to advertise studies that are supposed to prove accuracy. One must examine these closely. For example, we have seen a study where the test measurements were only conducted shortly after calibration. Unfortunately, this says little about the quality of the measurement results.

Study

An international review in JAMA Cardiology (April 2025) comes to a sobering conclusion: So far, no cuffless blood pressure measuring device has passed the strict accuracy tests that apply to conventional upper arm cuffs. Most models must first be "adjusted" with a conventional cuff and can then deviate by 5 to 10 mmHg from the actual value - especially when moving, exercising, or sleeping at night. Additionally, factors such as skin pigmentation, obesity, vascular stiffness, arrhythmias, or tremors affect the optical sensors (PPG) of these devices and increase measurement errors. Such inaccuracies raise the risk of overdosing or underdosing blood pressure medications. Therefore, experts recommend using only devices that have been proven to be accurate in independent testing procedures for the time being and to consider cuffless models as interesting but still immature supplements.

Result

If high values are measured during calibration, these will also appear in everyday use. If the calibration values are in the normal range, normal values will also be measured in everyday life. This is still too much guesswork, estimation, or rolling the dice to be truly useful. Especially with high blood pressure, the values can fluctuate more significantly than the calibration of the cuffless device wants to admit and allow.

In practice, we prefer to forgo the Aktiia bracelet because it is uncomfortable to wear and often needs to be taken off and put on due to lack of waterproofing. In return, one receives little helpful measurement results.

The Galaxy Watch is very useful as a smartwatch. However, due to the rather unbelievable measurement results, we lost sight of the regular measurements - the measurement function was hardly used anymore. When the watch then wanted to be calibrated every month, we preferred to turn off the function entirely rather than have to deal with it once a month for nothing.

The OptiBP app would be straightforward here because one would always have it with them. However, the ongoing subscription costs of the app are still too high given that the values are still too unreliable.

Conclusion April 2025: Unfortunately, there is still no way for high blood pressure patients to avoid the cuff.

Hybrid of blood pressure watch and smartwatch: Huawei Watch D

Huawei offers the Huawei Watch D, a proper smartwatch that additionally provides blood pressure measurement with an integrated cuff. Since this is a measurement with a cuff - similar to a conventional measuring device - what has been said here does not apply. For more information, see our article on blood pressure watches.

Blood pressure measurement with the camera

There are also providers that determine some vital parameters with a 60-second video of the face. This includes blood pressure. This is very innovative, so we looked at the solution from Binah.ai. However, in our test, the determined blood pressure was about 15 mmHg off from the value from the measuring device. Unfortunately, that is the state as of the end of 2023. Perhaps there will be better results in the future.

Sources:

This article is from BloodPressureDB – the leading app since 2011 that supports hundreds of thousands in blood pressure monitoring every day. Our content is based on carefully researched, evidence-based data and is continuously updated (as of 04/2025).

Author Horst Klier has been intensively dealing with high blood pressure since 2002 initially due to personal experience and since 2009 as a developer of BloodPressureDB; thanks to his widely used app and expert platform as well as numerous publications, he is now considered a recognized blood pressure expert. As the author of several health guides and specialist articles, he conveys complex knowledge in an understandable and practical manner.