ACTIVITY/FITNESS METRICS
The daily step total is one of the most popular, and useful, metrics tracked by wearables.
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18. Step counts, calories burned and more
Nearly all wearables track steps. And while most step counts aren’t perfectly accurate, they do provide a useful snapshot of how much activity you’re getting, says Kvedar, giving you “a sense in the middle of the day [of] whether you’ve actually done anything or not.”
Wearables use step counts, built-in GPS, motion sensors and personal information such as height, weight and age to calculate other metrics such as calories burned, pace, speed and distance traveled.
While 10,000 steps a day is always touted as the gold standard, research suggests there’s nothing magical about the number. In general, any increase in movement will improve your health.
19. Movement reminders
Many devices are programmed to give you reminders — a little buzz, or a pop-up saying “Time to move” — if you’ve been sitting too long. That’s important, because avoiding long stretches of sitting is important for health, no matter how much exercise we get. A 2024 study published in BMJ Open that focused on wearable devices found that the reminders were effective at boosting activity levels.
20. VO2 Max
This measurement of the maximum amount of oxygen a body can use during exercise is considered one of the best indicators of cardiovascular fitness and endurance. A true VO2 test, however, is done in a lab, where you exercise while wearing a mask, says Cheema. Wearables estimate VO2 using proprietary algorithms trained on data from people who have done the lab testing, Cheema explains. A 2025 review found that wearables provided a reasonable estimate of VO2 max levels, but accuracy varied by device, and the numbers may have been less accurate for people with very high or very low fitness levels.
HEART HEALTH METRICS
Heart rate is one of several cardiovascular health measures that wearables can track.
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21. Heart rate
Wearables use sensors that shine light into your skin and measure changes in blood flow to estimate your heart rate, or how many times your heart beats per minute. Research shows that the measurement is reasonably accurate but becomes less reliable as exercise intensity increases. How the device rests against your skin is important, and smart rings tend to be slightly more accurate than watches. “A wrist strap has more ability to be worn either too tight or too loose, as opposed to a ring, which has a very consistent fit,” says Fanning.
22. ECG monitoring
Some smartwatches can perform a simplified electrocardiogram, or ECG, which measures the electrical activity of the heart. To take a reading, users place a finger on the watch, worn on the opposite wrist. It can be useful for flagging a possible problem if someone is having symptoms or has known heart issues, Cheema says, but it doesn’t compare to the ECG you get in the doctor’s office. Smartwatches use only one lead, or point of contact, while a medical-grade ECG typically uses 12 to provide a much more detailed analysis.
23. Heart rate variability
This metric measures the differences in time between each heartbeat. A higher variability may indicate that your heart is quickly adapting to stress, exercise and recovery, Dennis-Coke says, while research has linked lower variability to poorer health. Wearables use heart rate variability alongside other scores related to sleep and stress, says Dennis-Coke.
24. Heart rhythm (AFib) alerts
Some wearables continuously monitor heart rhythm and alert you if they detect signs of atrial fibrillation, an irregular heart rhythm that increases stroke risk. Two meta-analyses found that smartwatches were fairly accurate at detecting possible AFib, though researchers found that false positives could occur and create unnecessary anxiety. If you receive an alert and experience symptoms such as chest pain, trouble breathing or are just feeling unwell, you should seek immediate medical attention.
SLEEP TRACKING
Quality of nightly sleep is another popular metric that wearable devices monitor.
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25. Sleep duration and quality
Many wearables monitor how long and how well you sleep, and how much time you spend in each sleep stage, using formulas that account for movement and various heart rate metrics. A 2024 study found that wearables were relatively accurate at estimating total sleep time, but still struggled to identify sleep stages and quality. Because the data are imperfect, Kvedar suggests using sleep metrics for observing patterns, such as how alcohol and stress affect your sleep, while taking detailed sleep scores “with a grain of salt.”
26. Sleep apnea alerts
A few smartwatches, including newer Apple and Samsung Galaxy models, use FDA-cleared technology to analyze breathing-related movement patterns over time to flag potential obstructive sleep apnea, a condition characterized by loud snoring and gasping during sleep. The American Academy of Sleep Medicine stresses that these alerts should be considered simple screening tools that should prompt you to talk to your doctor, and not a diagnosis.
EMERGENCY ALERTS
The loss-of-pulse alert, a relatively new feature, contacts emergency services if it detects that a user’s heart has stopped beating.
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27. Loss-of-pulse alerts
One of the newest emergency features on smartwatches is the loss-of-pulse alert, which received FDA clearance in 2025. Available on Google Pixel watches, it detects if the heart stops beating due to cardiac arrest, respiratory failure or another medical emergency. If it cannot detect a heartbeat, the device will first perform a loud countdown and, if you don’t respond, automatically call emergency services.
28. Automatic fall detection (and crash detection)
Many devices use motion sensors and accelerometers to recognize the signs of a serious fall or a severe car accident. If you don’t show movement afterward or respond to alerts asking if you’re OK, they automatically contact 911 and notify your emergency contacts.
29. SOS or medical alert button
Most wearables offer a way to quickly call for help with the press of a button: a valuable safety feature for older adults, Kvedar says. Typically, pressing and holding a button starts a countdown and calls emergency services if you don’t cancel it. Many devices also let you set up emergency alerts that send your location to family members or caregivers.
ADVANCED AND EMERGING METRICS
Wearables can now track heart rate variability and blood oxygen levels.
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30. Blood oxygen (SpO2)
Some wearables estimate your blood oxygen level using light sensors that analyze your blood through your skin. Low oxygen levels may signal breathing problems or illness. Studies are mixed, but a 2025 review in npj Digital Medicine concluded that Apple Watch oxygen measurements were reasonably accurate, though less reliable when oxygen levels were abnormally low. In one 2025 review of smart rings, the researchers noted that rings were “closer to arteries and capillaries” than smartwatches, which may improve signal quality and accuracy.
31. Glucose monitoring
Continuous glucose monitors track blood sugar levels throughout the day using a tiny sensor inserted under the skin, usually on the arm. People with diabetes commonly use medical-grade devices, but consumer versions are being marketed to anyone with an interest in nutrition and metabolic health. The real-time feedback can help you see how meals, exercise and sleep affect your blood sugar, Dennis-Coke says.
32. Stress scores
Many wearables now generate stress scores using measurements such as heart rate variability, heart rate, breathing patterns and skin temperature. The idea is to estimate how activated one’s nervous system may be throughout the day. But experts caution that stress is complicated, and the devices can’t always distinguish between emotional stress, excitement, exercise or poor sleep. “The question is, do you feel stressed?” Dennis-Coke says. “You always have to listen to your body. Your body is always the best indicator to tell you when something is or isn’t right.”
33. Recovery or ‘readiness’ scores
Some wearables combine data such as heart rate variability, skin temperature, sleep quality, and resting heart rate into a daily “readiness” or “recovery” score meant to estimate your body’s overall preparedness. Cheema says these scores sometimes pick up subtle changes and patterns that indicate your body is under stress. For example, he says, most doctors won’t pay attention to your body temperature or heart rate unless they’re outside the normal range.
However, fluctuations in those metrics can be “predictive that something is going on, whether it’s a heart attack or a blood clot or just the common cold,” says Cheema. So a big change in your score can be worth paying attention to and discussing with your doctor, especially if it persists and you have other symptoms as well.
WHAT TO CONSIDER WHEN CHOOSING A DEVICE
For the best experience with your wearable, first make sure it’s compatible with your cellphone.
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34. Compatibility with your smartphone
First, check out smartwatches that are the same brand as your smartphone — an Apple Watch if you own an iPhone, for example, or a Galaxy Watch if you have a Samsung Galaxy phone, suggests Courtney Lindwall, who writes about wearables for Consumer Reports. “You can expect the most seamless compatibility and the fullest range of features if you purchase a wearable that’s the same brand,” she says. Then you decide if that device meets your needs or if you want something different — say, a basic fitness tracker if you want something simple, or an advanced athletic watch from Garmin or Coros if you’re a serious runner or cyclist.
35. How many features do you want?
Dennis-Coke suggests considering how much technology you want to interact with on the device. Full-featured smartwatches can track dozens of health metrics, display texts and emails, run apps and even make calls, but they can also feel overwhelming. Simpler devices, such as basic smartwatches or fitness bands, are less distracting and easier to use. If your chief concern is safety, you’ll find simple medical-alert watches offering fall detection, emergency services alerts and location sharing without the fitness tracking. Some even have cellular service and don’t require a separate smartphone.
36. Battery life
Battery life across wearables varies widely. Smartwatches with big screens and many features usually require daily charging, Lindwall says, while simpler bands, rings and some Garmin watches will last a week or longer on a single charge. “Consider how you plan to use your watch,” says Lindwall. “Do you want to wear it to sleep every night for sleep tracking? Do you want to log long-distance runs or bike rides?” Consumer Reports tests the battery performance of different models in its ratings, which are available to subscribers.
37. Comfort and ease of use
Because you’ll ideally wear the device every day, comfort matters. Wearables come in many sizes, with different screen sizes, strap materials and weights. Lindwall recommends trying the device on in person if possible. “Watches with large screens may be uncomfortable or obtrusive on smaller wrists, while others prefer large displays for more clearly seeing notifications or workout stats,” she says. Ease of navigation is also important; some users may find it easier to use models with simpler interfaces or buttons instead of a touchscreen.
38. Cost and subscription fees
Wearables range from basic pedometers that cost less than $50 to high-end smartwatches that cost several hundred dollars. Check whether the brand charges a monthly subscription fee, ranging from a few dollars to $30, which is often required to access advanced insights or detailed health reports. The Oura Ring ($6/month), Whoop (Starting at $199/year) and some Fitbit and Garmin services require subscriptions, so it’s important to factor in ongoing costs before buying. If you purchase an LTE-enabled device, you will need to add it to your cellular plan.
If you have a health spending account (HSA), a health reimbursement account (HRA) or a flexible spending account (FSA), you might be able to use it to pay for your wearable devices. Check your account’s terms and policies before purchasing, though; it may require a letter of medical necessity from your health care provider.
39. How it uses your data
Wearables collect vast amounts of personal information, so it’s worth considering how each brand protects your privacy, Fanning says.
If privacy is a major concern, he suggests simpler devices that don’t rely heavily on cloud-based apps. A 2025 npj Digital Medicine study examined the privacy policies of wearable device manufacturers and ranked them according to privacy risk. Google “emerged as the overall leader in privacy protections,” according to the study’s authors, followed by Apple. Xiaomi (Amazfit) was rated the worst-performing company.
Whoop, the fitness band, was also a low performer, while Garmin, Oura, Fitbit and Polar landed in the middle tier. The study authors cautioned that they evaluated the company’s written privacy policies, which may not match their real-world data practices.
HOW TO GET THE MOST OUT OF YOUR WEARABLE
Stick to a charging schedule for your wearable device.
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40. Choose a regular time for charging
Experts say charging habits matter more than people realize. If you choose a device to monitor your sleep, for example, you’ll be wearing it overnight, so you will have to charge it during the day. Fanning recommends building charging into your existing routines: while showering, for example.
41. Check it regularly, but not obsessively
Fanning recommends putting simple metrics, such as daily steps, front and center on your device’s main screen, as this can motivate you to change your habits. He especially likes the Apple Watch bar chart, which shows how many steps you’ve taken every hour. “If you looked at it an hour ago and then again and it hasn’t changed, maybe you’ll get up,” he says. At the same time, he and other physicians caution against getting too consumed by the numbers.
42. Focus on patterns, not single metrics
In general, doctors recommend thinking of health data from wearables as useful estimates rather than precise medical measurements. They may help you assess how sleep, nutrition and alcohol consumption are affecting your health, Lindwall says, so that you can “make more informed lifestyle tweaks or begin a conversation with a medical professional.” Lindwall and other experts recommend focusing on trends over time and using the information as feedback to boost your health. “You have to be motivated,” says Kvedar. “There’s nothing magic about a feedback loop if you ignore it.”
The key takeaways were created with the assistance of generative AI. An AARP editor reviewed and refined the content for accuracy and clarity.