Monitoring your blood oxygen levels became a critical practise during the pandemnic, and has led to many smartwatch manufacturers making this a standard feature in their products from then on. Your body's blood oxygen levels serve as a warning sign of sleep apnea, trouble adjusting to high altitudes, or even serious pulmonary medical conditions.
Finger-based pulse oximeters are the most accurate for spot readings, but uncomfortable for sleep tracking. And you won't know if you need one unless you do some long-term monitoring first. That's where smartwatches with SpO2 tracking come in.
While blood oxygen monitoring is increasingly common on smartwatches these days, not all pulse oximetry sensors are created equal. Many watches are limited on when (or how often) you can take readings. Continuous SpO2 tracking is rare to find, and burns through battery life quickly. And of course, Apple Watch owners in the U.S. will need to look elsewhere, due to its legal issues with SpO2 readings.
Starting with the Garmin Venue 3, we've rounded up some of the best smartwatches with blood oxygen monitoring. We'll focus on the best options related to battery life, frequency of readings, related health-tracking features, accuracy, and more.
At a glance
Best overall
The Venu 3 offers up to 14 days of battery life, and you'll need plenty of juice for its all-day SpO2 mode that takes readings every five minutes. It also gives you ECG testing, skin temp, and HRV.
Best premium pick
The Garmin Forerunner 965 takes everything that makes the Forerunner 265 great and throws in a bigger battery and altitude acclimation tech for a higher price.
Best health data
The Fitbit Sense 2 is, first and foremost, a health-tracking tool, giving you SpO2 data, passive AFib, continuous stress, and reliable heart rate data. Be ready to pay for Fitbit Premium, though.
Best flagship
Despite some accuracy issues, the Galaxy Watch 7 has everything you could want in a wearable, including a powerful chip and continuous SpO2 tracking.
Most accurate
The original Withings ScanWatch received FDA approval for its SpO2 tracking, and the Withing ScanWatch is similarly designed to detect and monitor health conditions with laser accuracy.
Best overall
Garmin watches, generally speaking, are your best option for testing blood oxygen data. While some watches only offer SpO2 spot checks or data during sleep, Garmin is the rare brand to offer an all-day mode, measuring every 5–15 minutes and targeting moments when it detects a lack of motion. During runs, when the results would be unreliable, it takes fewer readings.
Nearly any of the best Garmin watches could claim this spot, since most have Pulse Ox readings and all-day mode. So why choose the Venu 3? It's one of few to offer an ECG tool for AFib detection and skin temperature data during sleep data, as well as the usual accurate heart rate & heart rate variability (HRV) data. If you care about SpO2, you probably want as much other health data as possible.
In addition, the Garmin Venu 3 has the brand's latest Sleep Coach for judging your sleep quality, the enhanced Body Battery tool that detects what's draining your energy, and a Jet Lag Adviser to judge your recovery during travel. It's missing Garmin's acclimation mode — which we'll explain with our next pick — but it's otherwise on the cutting edge for Garmin software.
More generally, our Garmin Venu 3 review runs through its many positives compared to other Garmin watches, from its bright AMOLED display and more stylish design to its built-in mic and speaker for Bluetooth calls and voice assistant commands. You can even stream Spotify playlists. It's not as smart as your typical smartwatch, but it's as close as a fitness watch will get you.
Best premium pick
Garmin watches tend to be expensive, so we chose the Venu 3 as the best smartwatch for blood oxygen data in part because it's "only" $450. If you can spare a little more, however, the Garmin Forerunner 965 is a better SpO2 option in three key respects.
First, the Forerunner 965 lasts 23 days in standard use. All-day SpO2 mode will significantly cut into that number, but you'll have more leeway than the 14-day Venu 3 will give you. If you only need spot checks or sleeping data, that might be less of a concern.
Second, only the Forerunner 965 has Garmin's Altitude Acclimation mode. When you're above 800 meters, it'll take averages of your blood oxygen, respiration rate, and resting heart rate to see how well you adapt to higher altitudes over three weeks. Serious athletes from climbers to marathoners could benefit from this tool.
Third, the Forerunner 965 has other cutting-edge fitness features for runners and cyclists. Our Garmin Forerunner 965 reviewer gushed over tools like training readiness, training load status, real-time stamina, and other metrics that helped him improve as a runner.
Aside from the high price, the downside to choosing the Forerunner 965, is that its last-gen Elevate v4 sensor lacks ECG spot readings and skin temperature data. Your choice may depend on whether you feel you need that information or not.
Best health data
If you care about blood oxygen data, then you're probably also interested in other bodily health data, too. Most smartwatches track heart rate and SpO2, but if you need more information, then the Fitbit Sense 2 is an excellent choice to consider — if you don't mind paying for Fitbit Premium.
We'll note upfront that the Fitbit Sense 2 can't take SpO2 spot checks. That might be a dealbreaker for you! We're still including it because its SpO2 app automatically sends this data to the Fitbit app overnight. Long-term graphical data during sleep is arguably more useful than random spot-checks for people suffering from sleep apnea. Plus, you can export that data to your doctor from the app — something competing brands don't offer.
In addition, the Fitbit Sense 2 can catch irregular heart rhythm, both actively with the ECG and passively with the HR sensor. The latter also captures HRV data to determine overnight energy recovery. The Sense 2's continuous electrodermal sensor (cEDA) can detect your current stress levels, and your temperature sensor tests the quality of your sleep at night.
Our Fitbit Sense 2 reviewer praised the watch for its redesign compared to the original Fitbit Sense. It's narrower, more comfortable, has a physical button to select things instead of an annoying capacitive touch button that you had to squeeze and didn't always work, and uses a revamped UI that we liked. Plus, you have the benefit of Google's Fitbit acquisition in that it gets access to Google Maps and Google Wallet, something that regular fitness watches can't usually access.
You may also want to consider the Fitbit Charge 6, which offers the same SpO2 tech and a similar battery life for half the price of the Sense 2. We only chose the Sense 2 over it because the Charge 6 technically is a fitness tracker, not a smartwatch.
Best flagship
Hands down, Samsung makes the best Android smartwatches, with the Galaxy Watch 7 as our current favorite flagship. Aside from loving the One UI 6 Watch interface, we really appreciate how Samsung stays at the cutting edge of health tracking. With the Galaxy Watch 7, you can spot-check SpO2 data using the relevant Tile, or measure during sleep.
In addition to SpO2 data, Samsung also measures your heart rhythm, body composition, and skin temperature. Plus, it offers the De Novo FDA-authorized Sleep Apnea feature, which can help you detect potential signs of sleep breathing issues so you can take appropriate measures. But note that this feature is exclusive to Samsung Galaxy phones, accessed through the Samsung Health Monitor.
In our Galaxy Watch 7 review, we loved the additional LEDs that track both heart rate and blood oxygen, which are designed to help you get more accurate tracking during high-intensity workouts. Our reviewer found that the readings felt more responsive, with fewer holes in the readings than he found with the Galaxy Watch 6.
While the Galaxy Watch 7's 33-to-36-hour battery is well below what Garmin or Fitbit provide, many people care more about getting apps, Google Assistant, and other smarts that a typical fitness watch could never offer. So we've included it here as a more balanced pick compared to the other specialized entries.
Most accurate
Most smartwatches have Pulse Ox these days, but you can never be fully sure how accurate the readings are. While most smartwatches ask for FDA approval for the accuracy of their heart rate monitors, they don't do the same for their SpO2 sensors because they're much more difficult to get right.
In fact, as far as we know, only one smartwatch has SpO2 tracking FDA approval: the Withings ScanWatch. While the ScanWatch 2 isn't technically "FDA cleared" for oxygen saturation of arterial hemoglobin, you can be confident that it's accurate since the original ScanWatch cleared the requirements.
This version improves on the original with additional sensors and software for continuous health monitoring, including variation of the baseline body temperature, female cycle tracking, heart rate variability, and automatic recognition of 40+ activities.
This isn't your traditional smartwatch with proper apps, but it can also last 30 days per charge with automatic 24/7 heart rate monitoring. The previous gen model was "clinically validated oxygen saturation" readings — taken at the UCSF Hypoxia Research Laboratory in San Francisco — that were "validated against the gold standard which involved blood oxygen samples analysis." In other words, you can trust that the SpO2 data is this step-up model is just as accurate.
The Withings ScanWatch combines this SpO2 data with HRM, breathing, and movement data for some of the best sleep tracking data and sleep apnea detection you can get from a device that isn't medical-grade. It can also detect AFib and offers some standard workout tracking, though not quite at the level of a Garmin or Fitbit.
While Withings didn't get clinical approval for SpO2 with the ScanWatch 2, calling it a "wellness feature," it's worth reiterating that we assume it uses the same technology and is equally accurate. If you're adamant about something with FDA approval, though, you can go with the Withings ScanWatch instead.
FAQ
Why do you need a fitness smartwatch with blood oxygen monitoring?
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Hypoxemia, or low blood oxygen levels in your blood, is a serious condition caused by a variety of possible ailments. And without a pulse oximeter, you may not know that it's low blood oxygen that's causing the problem.
According to the Cleveland Clinic, symptoms can include headaches, shortness of breath, tachycardia, coughing, and (in extreme cases) bluish skin. Plus, of course, sleep apnea can cause other symptoms like poor and sweaty sleep, depression, and an inability to regain energy.
One common reason for low SpO2 scores at night is sleep apnea. The American Medical Association says that about 30 million people in the U.S. suffer from it, but only 6 million have a diagnosis for it. It goes unnoticed for many, hurting their sleep quality without them ever realizing it. But a smartwatch can detect these symptoms.
Which Garmin watch is best for blood oxygen monitoring?
Almost every Garmin watch supports all-day SpO2 data, aside from a few older models. You may want to choose based on longest battery life, but long-lasting watches also tend to be bulkier, which could make sleep tracking less comfortable. It's about finding the right balance.
Athletes who need Garmin's altitude acclimation widget will typically find it on Garmin's priciest watches like the Fenix or Epix watches. For something a little more affordable, you could choose the Garmin Instinct 2X Solar or 2 Solar, or any of the Forerunner 9X5 models.
If you're more generally looking for sleep quality data, the Venu 3 is a good option because of its solid battery life, Sleep Coach, and skin temperature data. But it's on the expensive side; the Garmin Forerunner 165 will save you $200, lasts 11 days, and has a couple more running tools that you'll appreciate. Not a bad trade-off!
How to choose
Blood oxygen monitoring has become so commonplace in advanced smartwatches that you almost assume it'll be there. But beyond the physical presence of the sensor, it's just as important how the Pulse Ox actually works on your watch and how the software makes use of the data.
Both Fitbit and Garmin generally take a similar approach, silently collecting blood oxygen data and giving you a score or average of how well you're actually sleeping. The difference is that you can manually take a SpO2 reading on the Garmin Forerunner 265 whenever you want, while Fitbits mostly run behind the scenes. Either way, they'll give you a general sense if you're having trouble getting enough oxygen while sleeping, and their large batteries ensure running the Pulse Ox won't require daily charges.
The Galaxy Watch and Pixel Watch support nightly SpO2 readings as well, if you want a more traditional smartwatch experience. The Apple Watch Series 9 and Ultra 2 used to track SpO2 data before having to disable it in the U.S. for legal reasons, so iPhone owners will have to look elsewhere until Apple finds a more legally appropriate replacement.
You may also want to consider smart rings like the Oura Ring 4 or Samsung Galaxy Ring. They typically measure SpO2 data passively at night, with a much more comfortable sleeping experience than you'd get with a smartwatch.
