Samsung Health oxygen saturation readings are best treated as wellness estimates, not exact clinical measurements. A published study found reasonable agreement for Galaxy Watch 4 readings taken during sleep in a specific group, but it does not establish accuracy for every Galaxy Watch, daytime spot checks, or any individual reading. The U.S. Food and Drug Administration (FDA) warns users not to rely on a pulse oximeter reading alone.
What the Galaxy Watch 4 study found
A 2022 study evaluated the Galaxy Watch 4 as a wrist-worn reflectance pulse oximeter during sleep. Researchers enrolled 97 adults with sleep disturbances and compared simultaneous watch readings with a transmittance pulse oximeter used during polysomnography, the study’s reference measurement. The findings apply to that device and setting, not automatically to other models or uses. Read the study.
As an Amazon Associate I earn from qualifying purchases.
The study authors reported an overall root mean squared error (RMSE) of 2.3% and a bias of −0.2%. RMSE summarizes the size of errors across the study data; it does not mean every reading was within 2.3 percentage points of the reference. Bias describes average directional difference and likewise cannot predict the error in a particular reading.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Data quality is another important qualification: 26.5% of data were rejected, attributed to fluctuations in contact pressure and discarding data below 70% saturation. The usable results therefore do not represent every recorded point.
#1 Best Overall
![Samsung Galaxy Watch 8 40mm Bluetooth Smartwatch, Cushion Design, Quick Button, Sleep Coaching, Now Bar, Running Coach, Energy Score, Graphite [US Version, Amazon Exclusive 2Yr Warranty]](https://m.media-amazon.com/images/I/41pVUmtVzHL._SL160_.jpg)
- WHY GALAXY WATCH8: Advanced health and sleep tracking features.* A lighter, more snug design for all day comfort.* Improved user interface.* Personal AI assistant for hands free help.⁴* 2-Year Warranty.
- SLEEP SMARTER. LIVE BETTER: Energize your days with a great night’s rest using Advanced Sleep Coaching¹ - improved with even more ways to keep your nights on track. Plus, Bedtime Guidance² helps you find your optimal bedtime.
- YOUR RUN, YOUR COACH: Step up your running routine with a Running Coach³ that analyzes your performance and gives you real-time feedback. Training for an event? Try specific programs built for 5Ks, marathons and more.
- NEW DESIGN. LIGHTWEIGHT FEEL: Maximize your days with a minimalist design. The sleek, thinner-than-ever silhouette makes Galaxy Watch8 look as good as it functions. With a snug fit and sporty style, it gives you readings without getting in your way.
- A PERSONAL ASSISTANT, RIGHT ON YOUR WRIST: Your Watch just became your personal assistant.⁴ Stay one step ahead of your day with a watch that helps you navigate your tasks and to-do lists.
Accuracy varied across sleep apnea groups
For participants grouped by obstructive sleep apnea severity, the study reported these RMSE values:
| Study group | RMSE reported by the 2022 authors |
|---|---|
| Normal | 1.65 ± 0.57% |
| Mild obstructive sleep apnea | 1.76 ± 0.65% |
| Moderate obstructive sleep apnea | 1.93 ± 0.54% |
| Severe obstructive sleep apnea | 2.93 ± 1.71% |
The group differences are study results, not a promise of equivalent performance for another person or a different watch model.
Rank #2
![Samsung Galaxy Watch9, Graphite, 40mm Bluetooth Smartwatch | AI Assistant, Fitness Tracker, Sleep Coaching and Running Coaching with Heart Rate Tracking [US Version, 2 Yr Warranty]](https://m.media-amazon.com/images/I/31Q6G58gP9L._SL160_.jpg)
- TRACK HEALTH PATTERNS¹ IN YOUR SLEEP WITH VITALS²: Stay aware of the subtle changes in your body with Vitals¹–it tracks health metrics while you sleep, catches shifts from your usual patterns, and provides tailored guidance based on the insights.²
- A PERSONALIZED COACH FOR YOUR FITNESS GOALS: Whether you're building endurance for a long trek or training to build muscle, Fitness Index³ delivers tailored guidance based on your fitness level goals. Finally, train smarter with your fitness watch.
- EVERYDAY AI ASSISTANCE, SIMPLIFIED: With the Galaxy Watch9, you can just raise your wrist, start talking naturally and get instant AI assistance⁴—no wake phrase needed. This smart watch won’t slow you down.
- ONE PERSONALIZED SCORE TO KNOW YOUR HEART BETTER: Instead of checking multiple metrics separately, track the single Heart Health Score⁵ based on sleep time, BMI, activity and vascular load to stay aware of your wellness.
- TRACK YOUR NIGHTS. OWN YOUR DAYS: Galaxy Watch9 gives you personalized recommendations and habit-building guidance with Advanced Sleep Coaching.⁶ Plus, Bedtime Guidance⁷ helps you find your optimal bedtime so you can wake up feeling refreshed.
The study did not validate the watch as a sleep apnea diagnostic tool
In the same study, a Galaxy Watch 4 oxygen desaturation index threshold of at least 5 events per hour predicted a polysomnography apnea-hypopnea index of at least 15 per hour with 89.7% sensitivity, 64.1% specificity, 79.4% accuracy, and an area under the curve of 0.908. These are results for the study’s defined comparison and threshold; they do not establish that Samsung Health diagnoses sleep apnea. Samsung Electronics appears among the author affiliations, and the authors called for further wearable algorithm improvement.
Why a watch reading can be unreliable
Pulse oximetry depends on a usable sensor signal and can be affected by both how the device is worn and individual conditions. Samsung’s Galaxy Watch 3 instructions advise wearing the watch snugly, covering its sensor, staying still, and not talking during measurement. Samsung’s developer guide also says to check wrist location and pose and avoid movement. Good technique can improve measurement conditions, but it cannot guarantee accuracy.
Rank #3
![Samsung Galaxy Watch 8 40mm Bluetooth Smartwatch, Cushion Design, Quick Button, Sleep Coaching, Now Bar, Running Coach, Energy Score, Silver [US Version, Amazon Exclusive 2Yr Warranty]](https://m.media-amazon.com/images/I/31LaWf6wVqL._SL160_.jpg)
- WHY GALAXY WATCH8: Advanced health and sleep tracking features.* A lighter, more snug design for all day comfort.* Improved user interface.* Personal AI assistant for hands free help.⁴* 2-Year Warranty.
- SLEEP SMARTER. LIVE BETTER: Energize your days with a great night’s rest using Advanced Sleep Coaching¹ - improved with even more ways to keep your nights on track. Plus, Bedtime Guidance² helps you find your optimal bedtime.
- YOUR RUN, YOUR COACH: Step up your running routine with a Running Coach³ that analyzes your performance and gives you real-time feedback. Training for an event? Try specific programs built for 5Ks, marathons and more.
- NEW DESIGN. LIGHTWEIGHT FEEL: Maximize your days with a minimalist design. The sleek, thinner-than-ever silhouette makes Galaxy Watch8 look as good as it functions. With a snug fit and sporty style, it gives you readings without getting in your way.
- A PERSONAL ASSISTANT, RIGHT ON YOUR WRIST: Your Watch just became your personal assistant.⁴ Stay one step ahead of your day with a watch that helps you navigate your tasks and to-do lists.
The FDA lists poor circulation, skin pigmentation, skin thickness, skin temperature, current tobacco use, and fingernail polish among factors that can affect pulse oximeter accuracy. Those are general pulse oximetry cautions; the Galaxy Watch 4 study did not quantify the effect of each factor for Samsung watches or establish Samsung-specific accuracy by skin pigmentation subgroup.
How to get a more usable reading
- Wear it securely. Follow the guidance for your watch model; Samsung’s Galaxy Watch 3 instructions say to wear it snugly and cover the sensor.
- Keep your hand and body still. Avoid talking or moving while the measurement is underway.
- Check placement and pose. Samsung’s developer guide advises checking the watch’s position on your wrist and your pose if measurement is difficult.
- Interpret the result in context. A watch reading is an estimate; do not treat a single number as proof that your oxygen level is normal or abnormal.
Samsung’s developer guide states: “If you have trouble measuring SpO2, please check the watch’s location on your wrist as well as your pose. And please be careful not to move.”
Rank #4
![Samsung Galaxy Watch 8 Classic 46mm Bluetooth Smartwatch, Cushion Design, Rotating Bezel, Quick Button, Sleep Coaching, Running Coach, Energy Score, Black [US Version, Amazon Exclusive 2Yr Warranty]](https://m.media-amazon.com/images/I/51Vc6CWcxAL._SL160_.jpg)
- WHY GALAXY WATCH8 CLASSIC: Timeless design.* New lug system for easy band detachment & replacement.* Advanced health & sleep tracking features for total body wellness.* Improved user interface.* Personal AI assistant for hands free help.¹* 2-Yr Warranty
- BUILT TO PERFORM. DESIGNED TO IMPRESS: Show off your style with an iconic design that blends tradition with cutting-edge innovation.¹ A brighter screen makes everything easy to see, and a rotating bezel gives you access to your favorite apps
- YOUR EVERY COMMAND, RIGHT ON YOUR WRIST: Get a little extra help with day-to-day tasks. Galaxy Watch 8 Classic features a personal AI assistant¹ that helps you get things done hands-free. Simply speak the command and your Watch makes it happen
- UNLOCK THE SECRETS TO BETTER SLEEP: When you get good sleep, it feels like anything is possible. Start each day with more energy and better focus using Advanced Sleep Coaching² - improved with even more ways to help you sleep smarter
- QUICK UPDATES, AT A GLANCE: Get updates, select apps and more with Now Bar³,⁴ and an improved user experience. Now Bar conveniently puts the info you use the most - like weather, news and more - right on your main Watch screen
What Samsung Health readings can—and cannot—tell you
Samsung characterizes the Galaxy Watch 3 oxygen saturation feature as wellness tracking and says that watch is not a medical device. FDA materials distinguish medical-purpose devices from general wellness products; general wellness pulse oximeters are not evaluated for clinical decision-making or for deciding whether to seek medical intervention. That description of the Watch 3 should not be treated as a model-by-model regulatory statement about every Galaxy Watch.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsThe FDA’s January 2025 document on pulse oximeters is draft guidance, explicitly nonbinding and not for implementation. It proposes recommendations for evaluating medical-purpose pulse oximeters, including taking skin pigmentation into account; it is not a final rule or Samsung-specific approval.
Best Value
![SAMSUNG Galaxy FIT 3 [2024] 1.6' AMOLED Display | 14 Days Battery Life | 100+ Watchfaces | 100+ Exercise Modes | International Model - (Gray)](https://m.media-amazon.com/images/I/31JyN7HkB8L._SL160_.jpg)
- Vibrant 1.6” AMOLED Display – Large, high-res screen with smooth touch for easy navigation
- 5ATM & IP68 Water Resistance – Swim-ready and dust-resistant for active lifestyles
- Up to 14 Days Battery Life – Powerful 208mAh battery for long-lasting performance
- 101+ Workout Modes with Auto Detection – Automatically tracks common workouts for seamless fitness tracking. Advanced Health Tracking – Includes sleep coaching, SpO2, heart rate, and snore detection
- International Model No Warranty in the US. ONLY compatible with Android devices. Samsung Pay - Not Supported. NOT compatible with iPhone or iOS devices.
The FDA’s consumer guidance is direct: “Do not rely only on a pulse oximeter.” Consider how you feel as well as any number. If a reading concerns you, or you have serious or worsening symptoms, contact a healthcare professional. A separate fingertip pulse oximeter may offer another estimate, but it is also subject to pulse oximetry limitations and is not definitive.
What the evidence does not establish
- Accuracy for current Galaxy Watch models other than the Galaxy Watch 4 in the cited sleep study.
- Accuracy of daytime spot measurements.
- Samsung-specific performance across skin pigmentation groups.
- A guarantee that an individual reading falls within the study’s average error statistics.
- A basis for diagnosing sleep apnea or another medical condition from Samsung Health readings.
When comparing readings, distinguish wrist reflectance from fingertip or other transmittance measurements, sleep measurements from daytime spot checks, the exact watch generation, and comparison with a clinical reference from comparison with another consumer device. The published study supports only a Galaxy Watch 4 sleep-measurement comparison with reference oximetry during polysomnography.
Quick Recap
Sources
- 2022 Galaxy Watch 4 sleep oxygen saturation study
- FDA consumer guidance on pulse oximeter accuracy and limitations
- Samsung Galaxy Watch 3 oxygen saturation measurement guidance
- Samsung developer measurement guide
- FDA January 2025 draft guidance for pulse oximeters
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
