What is vascular age? What smartwatch pulse-wave studies show

Short answer: Vascular age is the apparent age of your arteries, as opposed to your chronological age, the years since you were born. It is usually estimated from pulse wave velocity (PWV), the speed of the pressure pulse along your large arteries. Stiffer arteries carry the pulse faster, so a PWV that is typical of an older age group means an older vascular age.

Clinics measure PWV between the neck and the groin with dedicated equipment. Smart scales and some smartwatches now offer their own estimates, and the largest study so far, 165,549 Huawei watch users in China, shows both what the wrist version can do and where it falls short.

This article is educational and is not medical advice. Talk with a clinician about your cardiovascular risk.

Arteries vs birthday: the definition

Blood vessels change as we get older. The large arteries become stiffer and wider, and the first part of the aorta gets longer. Charlton and colleagues describe this process as vascular aging. They define vascular age as the apparent age of the blood vessels, set against chronological age, meaning the time since birth (Charlton et al., 2022, doi:10.1152/ajpheart.00392.2021). The same review notes that indicators of vascular aging, such as aortic stiffness measured by carotid-femoral PWV, predict cardiovascular disease and death from any cause.

Two people born in the same year can have very different arteries, and chronological age cannot tell them apart while a stiffness measurement can. If you are 45 and your arteries behave like those of a typical 60-year-old, your vascular age is older than your birthday suggests.

For the physiology of why stiff arteries speed up the pulse, see our explainer on what pulse wave velocity is and the shorter PWV glossary entry.

How PWV becomes a "vascular age"

PWV is distance divided by time. In the clinic, a technician records the pulse at the carotid artery in the neck and the femoral artery in the groin, measures the distance between the two sites, and divides by the delay. That carotid-femoral PWV (cfPWV) is the standard reference for aortic stiffness.

Turning a PWV into an age needs a reference table: what PWV looks like at each age in healthy people. The best-known European table comes from the Reference Values for Arterial Stiffness' Collaboration, which pooled 16,867 people from 13 centres in eight countries (Reference Values for Arterial Stiffness' Collaboration, 2010, doi:10.1093/eurheartj/ehq165). After standardizing the different devices, it found that PWV rose with age and with blood pressure, and that the rise with age was steeper at higher blood pressure. Its "normal values" come from 1,455 people without cardiovascular risk factors and with optimal or normal blood pressure.

Source: Reference Values for Arterial Stiffness' Collaboration (2010), Table 4, normal-value population.

A vascular age is, at heart, a lookup: find the age group whose typical PWV matches yours. A cfPWV of 8.1 m/s is the median for people in their 50s in this table. Commercial products layer their own algorithms and user data on top, but the logic is the same. It also means the answer depends on which reference group you are compared against.

What a 165,549-user smartwatch study showed

Wang and colleagues analysed every adult who took a valid PWV reading on one of four Huawei watches between December 2020 and August 2022, across 34 provinces in China (Wang et al., 2026, doi:10.3389/fcvm.2026.1865667). After data cleaning, 165,549 users remained. They were 88% men, with an average age of about 42, and a median smartwatch PWV (SW-PWV) of 7.79 m/s.

How the watch estimates PWV

The watch cannot reach your carotid or femoral artery. Instead, you sit quietly for 10 minutes, wear the watch on your left wrist, and touch it with your right index finger for 30 seconds, so the watch can record an ECG while its optical sensor records a PPG pulse at the wrist. The algorithm times the gap from the ECG R wave to the foot of the PPG pulse:

where $T_{\text{PPG foot}}$ is when the foot of the wrist pulse arrives, $T_{\text{ECG R}}$ is the time of the R-wave peak, and $L$ is an effective arterial path length that the watch estimates from body measurements. The paper calls the interval pulse transit time; reviews of PPG methods file ECG-to-PPG timing under pulse arrival time (Charlton et al., 2022, doi:10.1152/ajpheart.00392.2021). The pulse transit time entry covers the difference.

Two details matter for interpretation. First, the algorithm also folds in age, sex and BMI and is calibrated to earlier validation data. Second, the investigators did not have access to the source code. The output is a proprietary estimate of cfPWV, not a direct measurement.

How close is it? In an earlier validation, 347 volunteers aged 18 to 80 had cfPWV measured by both the watch and a Complior Analyse device. Agreement was good: a concordance correlation coefficient of 0.9045, mean absolute error of 0.66 m/s, and 95% limits of agreement from −1.77 to 1.86 m/s (as summarized by Wang et al., 2026, doi:10.3389/fcvm.2026.1865667).

Limits that wide mean a single reading can sit almost 2 m/s from the clinical value. That is more than the step between neighbouring age groups in the table above, such as 8.1 m/s in the 50s and 9.7 m/s in the 60s.

Readings by age

SW-PWV correlated with age (r = 0.63). The median rose from 7.33 m/s in users under 30 to 11.28 m/s in those 70 and older, with a jump between the 40s (7.66 m/s) and the 50s (8.96 m/s). Under 60, women had lower values than men. From 60 onward the sexes were similar. A regression on age, sex and BMI alone explained 60.9% of the variation in readings.

Because age, sex and BMI are inputs to the algorithm, the authors caution that these patterns describe the algorithm's output and are not independent evidence about biology. In the chart below, the smartwatch bars are far narrower than the clinical ones. The bars use different percentile ranges, so treat that as a rough comparison.