You’re scrolling through the health settings on your wrist, looking for that red light. You want to see how your lungs are holding up after a nasty bout of the flu or maybe you're just curious about your fitness levels. But there's a problem. If you own an SE, you’re likely realizing that apple watch se blood oxygen tracking isn't actually a thing. It’s frustrating. You see the Series 9 or the Ultra users boasting about their SpO2 levels, but your SE menu looks a bit... empty.
The truth is pretty simple, if a bit annoying. Apple intentionally left the Pulse Oximeter out of the SE lineup to keep the price down. It’s a classic budget-tier move.
But it’s not just about a missing icon. There is a whole mess of legal drama involving Masimo, patent disputes, and software lockdowns that has made the blood oxygen feature a headache even for people who paid $800 for the Ultra. If you're wondering whether you should upgrade or if there’s a workaround, we need to talk about what’s actually happening under the sapphire crystal.
The Hardware Gap: What Apple Watch SE Blood Oxygen Actually Means
The SE is the "greatest hits" version of the watch. You get the heart rate sensor, the GPS, and the fall detection. However, the hardware required for blood oxygen—a specific array of green, red, and infrared LEDs—is physically absent from the Apple Watch SE (1st Gen, 2nd Gen, and any current iteration).
You can't "unlock" it with a software update. It's not there.
Standard heart rate monitoring uses green lights (Photoplethysmography or PPG) to measure blood flow. Blood oxygen, or $SpO_2$, requires red and infrared lights because oxygenated and deoxygenated hemoglobin absorb those specific wavelengths differently. When the watch shines red light into your wrist, it measures how much bounces back. Without those specific red LEDs, the SE is essentially blind to the oxygen saturation in your bloodstream.
Apple decided that for $249, you get the essentials. Blood oxygen was deemed a "Pro" or "Series" feature.
Does it even matter for most people?
Honestly, probably not. Unless you have chronic obstructive pulmonary disease (COPD), asthma, or sleep apnea, checking your blood oxygen every twenty minutes is mostly just a way to drain your battery. For the average gym-goer, your heart rate and VO2 Max (which the SE can estimate) are much better indicators of cardiovascular health.
Still, there’s a psychological comfort in having all the sensors. I get it. We want the full dashboard. But if you’re looking at the apple watch se blood oxygen situation and feeling like you’re missing out on a life-saving tool, take a breath. Most doctors will tell you that a $20 finger pulse oximeter from the drugstore is more accurate than any smartwatch anyway.
The Masimo Legal Drama and the 2024 Ban
Here is where things get weird. Even if you decided today to go buy a Series 9 or an Ultra 2 to get that blood oxygen sensor, you might find it disabled.
Apple got into a massive legal fight with a medical tech company called Masimo. The International Trade Commission (ITC) ruled that Apple infringed on Masimo’s patents regarding pulse oximetry. Because of this, Apple had to stop selling watches with functional blood oxygen sensors in the United States for a period starting in early 2024.
If you buy a new Apple Watch Series 9 or Ultra 2 from Apple today, the blood oxygen feature is hard-coded to be "unavailable." It’s still in the SE category of "not having it," but for a much more expensive reason.
This makes the SE look like a smarter buy in hindsight. Why pay for a sensor that isn't allowed to work?
What the SE Can Tell You About Your Health
Just because the apple watch se blood oxygen sensor is missing doesn't mean the watch is a toy. It’s still a powerhouse for heart health.
- High and Low Heart Rate Notifications: This is the big one. If your heart rate spikes while you've been sitting still for ten minutes, the SE will buzz. It’s saved lives. No joke.
- Irregular Rhythm Notifications: It can still scan for signs of Atrial Fibrillation (AFib) by looking at the timing of your pulses, even without the ECG app found on the Series models.
- Sleep Tracking: It uses the accelerometer and heart rate sensor to guess your sleep stages. It’s surprisingly accurate for a budget device.
- Cardio Fitness (VO2 Max): This is a huge metric. While it doesn't measure blood oxygen directly, it uses your heart rate response during walks or runs to tell you how efficient your body is at using oxygen.
If you’re healthy and just want to close your rings, the SE is more than enough. You don't need a pulse ox to know you're out of breath after a 5K.
Comparing the SE to the Series 9 and Ultra
Let's look at the landscape. If you are dead set on getting $SpO_2$ data, you have to look outside the SE.
The Series 9 has the faster S9 chip, the brighter screen, and—legally permitting—the blood oxygen sensor. It also has the ECG (Electrocardiogram) app. The ECG is actually more clinically useful for many people than the blood oxygen sensor because it can detect specific heart rhythm issues that a simple pulse sensor might miss.
Then you have the Ultra. It’s a tank. It has the longest battery life and the best GPS. But again, in the US market, that blood oxygen feature is currently a ghost in the machine.
If you are a hiker or someone who spends a lot of time at high altitudes, the lack of apple watch se blood oxygen tracking might be a dealbreaker. At 10,000 feet, knowing if your saturation is dropping can be a safety issue. But for everyone else? It's a "nice to have," not a "need to have."
Why Apple didn't put it in the SE 2
The SE 2nd Generation was released in 2022. At that point, the Series 6, 7, and 8 all had blood oxygen sensors. Apple could have easily put the older Series 6 sensor into the SE 2.
They didn't.
Why? Product differentiation. If the SE had every health sensor, nobody would pay $399 for the Series 9. Apple needs a reason to upsell you. By keeping the SE "basic," they ensure that users who are truly health-conscious or have medical needs will spend the extra $150. It’s a classic business strategy. It keeps the entry price low for kids and first-time users while protecting the margins on the flagship products.
The Accuracy Problem: Wrist vs. Finger
Let's get nerdy for a second. Even if you had the apple watch se blood oxygen feature, how much would you trust it?
Wrist-based pulse oximetry is notoriously finicky. It’s "reflection" oximetry. The light goes in, hits the bone or tissue, and bounces back. Medical-grade finger clips use "transmission" oximetry, where the light goes through your finger to a sensor on the other side.
- Tattoos: If you have ink on your wrist, the blood oxygen sensor (and the heart rate sensor) will struggle or fail completely.
- Skin Tone: Studies have shown that darker skin tones can sometimes affect the accuracy of optical heart sensors, though Apple claims to have accounted for this with higher light intensity.
- Fit: If the band is loose, the light leaks out. If it's too tight, you restrict blood flow.
- Movement: You have to be dead still. If you move your arm during a manual blood oxygen check, it’ll likely fail.
For most people, the SE’s lack of this sensor is a blessing in disguise because it prevents "cyberchondria"—the act of panicking over a slightly low reading that was actually just caused by a loose watch band.
Alternatives for SE Owners
If you own an SE and you absolutely need to monitor your blood oxygen, don't sell your watch just yet.
You can buy a standalone Bluetooth pulse oximeter for about $30. These devices often sync with the Apple Health app. You clip it on your finger for 30 seconds, it takes a much more accurate reading than a watch ever could, and it dumps that data right into your iPhone.
It’s a two-device solution, sure. But it’s cheaper than buying a Series 9. Plus, you get the accuracy of a dedicated medical device.
Another option is looking at the competition. Garmin and Fitbit both include blood oxygen sensors in their mid-range and even budget trackers. If $SpO_2$ is your "must-have" metric, you might find that the Apple ecosystem is a bit too restrictive for your needs. Garmin, in particular, uses blood oxygen for "Body Battery" and altitude acclimation features that are arguably more useful than Apple's implementation.
The Future of the SE Lineup
We are hearing rumors about an Apple Watch SE 3. Will it finally get blood oxygen?
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It’s a coin flip. On one hand, the tech is now several years old and should be cheap enough to include. On the other hand, the legal battle with Masimo makes Apple hesitant to lean too hard into pulse oximetry right now. They might focus on other things instead, like a plastic body to lower the price even further or a slightly larger screen.
If I were betting, I’d say Apple keeps the SE as the "essential" health device. Heart rate, steps, sleep. That's the core.
Actionable Steps for Apple Watch SE Users
If you are currently rocking an SE and feeling the FOMO, here is what you should actually do:
- Check your Cardio Fitness levels: Open the Health app on your iPhone, go to "Browse," then "Heart," then "Cardio Fitness." This uses your heart rate and motion to tell you how your "engines" are running. It's a better long-term health marker than a random blood oxygen snapshot.
- Verify your Heart Rate zones: Ensure your birthdate and weight are correct in the Watch app. This makes the calorie burn and heart rate data much more accurate.
- Invest in a Pulse Ox if necessary: If you have a medical condition, spend the $25 on a finger-clip oximeter. Use the "Add Data" button in the Apple Health app to log your readings manually so your doctor can see them.
- Don't ignore the HR notifications: The SE is phenomenal at catching high/low heart rates. Make sure these notifications are turned ON in your watch settings.
- Stop worrying about SpO2 for fitness: Unless you are training for an ultramarathon at 14,000 feet, blood oxygen doesn't change enough during a normal workout to give you useful training data.
The apple watch se blood oxygen omission isn't a flaw; it's a trade-off. You saved money. You got 90% of the functionality. You missed out on one sensor that is currently a legal nightmare for Apple anyway.
If you truly need medical monitoring, a consumer smartwatch shouldn't be your primary tool. If you want a great fitness tracker that doesn't break the bank, the SE remains the best value in the lineup, even without the red lights.