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Last updated: November 16, 2025
Blood Oxygen (SpO₂) returns on supported Apple Watch models after you install the latest watchOS update, enable the feature in the Health app on iPhone, and confirm region/age eligibility. Use the steps below to turn it back on safely.
Best for: Apple Watch Series 6 and newer, Apple Watch Ultra/Ultra 2, Apple Watch Series 9 (see model details below).
Disclosure: As an Amazon Associate, we earn from qualifying purchases. It helps fund our testing at no extra cost to you.
We tested Blood Oxygen across Apple Watch Series 6, Series 7, Series 9, Ultra, and Ultra 2 over two weeks. We captured readings at rest and during light activity, noted setup friction, consistency of results, and how region/age settings and watchOS versions affected visibility.
Availability can change due to regional rulings, age settings (Family Setup/Child account), or firmware. After an update, a fresh iPhone setup, or region change, the toggle may switch off. The good news: if your model is supported and watchOS/iOS are up to date, enabling it in the Health app and turning it on in Watch settings usually restores the feature quickly.
Remember the sensor is optical (infrared/red/green LEDs and photodiodes). As with any optical sensor, skin tone, hair, tattoos, jewelry/band material, and skin temperature can affect readings. Before assuming “the sensor is broken,” double‑check fit and method first.
Note: Apple Watch is not a medical device. If you have symptoms or concerns, consult a healthcare professional regardless of readings.
In supported regions, Apple Watch Series 6 and newer (including Series 9 and Apple Watch Ultra/Ultra 2) provide Blood Oxygen measurements. Due to regulatory and age restrictions, availability may vary by country and account setup.
On Family Setup, certain health features can be limited. If your Apple ID age indicates a child account or you recently moved regions, you may see warnings in the Health app. Verify eligibility and try again.
Fast chip and reliable sensors make day‑to‑day use smooth. Excellent balance of price, battery, and features—we saw consistent SpO₂ results.
Rating: 4.3 (2,225) · 300+ bought in past month
$230.00
Bigger screen, longer battery, rugged build. Ideal if you want maximum visibility for on‑wrist vitals.
Rating: 4.3 (163) · 500+ bought in past month
$479.95
In testing, Series 9 stood out for short measurement times and reliable repeatability. Ultra 2’s brighter display helps you maintain a stable wrist posture outdoors, which reduces motion‑induced errors. Battery impact from background readings stayed manageable on both models.
Renewed units are great value, but band choice matters: very stretchy or loose fabric bands can introduce micro‑movement during short readings. We saw more consistent results with Sport Loop or modern magnet bands that maintain steadier contact.
| Model | Sizes | Battery | Blood Oxygen | Price |
|---|---|---|---|---|
| Apple Watch Series 9 | 41/45mm | Up to 18 hrs | Yes | $230 (renewed) |
| Apple Watch Ultra 2 | 49mm | Up to 36 hrs | Yes | $479.95 (renewed) |
For everyday health tracking value, Series 9 is the easy pick. If you want maximum battery life and a larger display for on‑wrist vitals, Ultra 2 stands out.
If the feature never appears: recheck iPhone region, Apple ID age, Family Setup status, and watchOS version. Unpairing and re‑pairing (after a backup) can also resolve visibility glitches.
If you care about health insights, interpret readings as trends, not single points. A week‑long downward trend is more meaningful than one low reading. Training load, altitude, sleep quality, and hydration all influence SpO₂ interpretation.
Apple Watch Series 9 — balanced choice for features, price, and accuracy.
Renewed Series 9 — most affordable path to reliable SpO₂ tracking.
Apple Watch Ultra 2 — larger display and longer battery for steadier readings.
Note: Apple Watch is not a medical device. If you experience symptoms or unusual values, consult a healthcare professional.
Update watchOS, enable the feature in the Health app, check age/region eligibility, and confirm Wrist Detection is ON.
Apple Watch Series 6 and newer, including Series 9 and Ultra/Ultra 2, in supported regions.
No. They’re for wellness and fitness insights only. Consult your clinician for medical concerns.
Yes, both can interfere. Try a different spot, warm your skin, and keep the watch snug.
Snug but comfortable, about 1–2 cm above your wrist bone for best sensor contact.
Eligibility or regional changes may have toggled it off. Re‑enable after updating and verifying settings.
Roughly 15 seconds. Rest your arm on a flat surface and remain still.
Only slightly for most users. Longer workouts or frequent checks may increase impact.
It depends on age settings and region. Check Apple’s guidance for eligibility.
No. Use them for trends. For symptoms or unusual values, consult a healthcare professional.
Generally good for trend tracking. Focus on nightly averages and trends rather than single points.
Different method and location. Don’t expect one‑to‑one; retest if you see large discrepancies.
Important Note: Purchases through our Amazon links support ongoing testing and content updates.
If you keep health reports or workout logs on your phone, it’s smart to convert and organize them for long‑term storage. You can quickly turn iPhone photos into a single PDF, extract a page from a PDF as a JPG, or to combine different documents, PDF dosyalarını birleştirin. Before sharing large files, compress your PDF can make things easier.
For Word or Excel outputs you receive from clinics, convert Word to PDF, convert Excel to PDF and convert PowerPoint to PDF are ideal. If you prefer to keep notes simple, convert TXT to PDF or to archive a web page, convert HTML to PDF is a great option.
If you want to add privacy before sharing, add a watermark to your PDF helps. If you work with images, compress and resize JPGs, crop and resize photos, merge images into a single visual and convert to/from WebP can speed up your workflow. For more content, check out our How‑to guides, Best Products recommendations , and for our most recent posts, visit The Latest sections.