Apple dropped two new smartwatches in September 2025, and if you’re an iPhone user trying to figure out which one to buy, the choice probably feels more confusing than it should be. Both the Series 11 and the SE 3 use the same processor, offer 5G connectivity, and support most of the same core features. So what’s actually different, and does it matter enough to justify the $150+ price gap?
The short answer is that it depends entirely on what you actually do with a smartwatch. But let’s dig into the nuances because the real story here is more interesting than the spec sheet suggests.
The Design Question Nobody Really Talks About
Here’s the thing about smartwatch sizing that nobody mentions until you’re holding both on your wrist: the 44mm SE 3 feels noticeably smaller than the 46mm Series 11, but after about two days of wearing the SE 3, you just stop caring. Your brain adjusts.
The Series 11 does have a significantly brighter display with double the peak brightness (2,000 nits versus 1,000 on the SE 3). In theory, this sounds like a big deal. In practice? I’ve worn both, and unless you’re squinting at your wrist in direct sunlight regularly, you won’t notice much difference in typical use. The displays look genuinely similar when you’re not actively comparing them side by side.
Color options tell a different story though. The SE 3 comes in exactly two flavors: midnight and starlight. That’s it. The Series 11 offers four aluminum colors plus three titanium options, including rose gold and shiny gold. If you care about aesthetics and want your watch to feel like an actual accessory rather than just a functional device, the Series 11 has more personality.
Battery Life: The Numbers Don’t Match Reality
Apple rates the Series 11 for 24 hours and the SE 3 for 18 hours. Sounds like the Series 11 crushes it, right? Except both watches hit low battery levels by the end of a typical day after getting notifications and doing a 30-minute workout. Both need overnight charging. That 6-hour difference on paper feels pretty meaningless when you’re plugging in either way.
Where the Series 11 Actually Pulls Ahead
Now we get to the stuff that legitimately matters. The Series 11 has sensors the SE 3 simply doesn’t have, and these aren’t gimmicks.
The Series 11 includes an electrical heart sensor for taking ECG readings, which can help detect atrial fibrillation. It also supports hypertension notifications and a blood oxygen app. The SE 3? None of that. If you’re someone who cares about advanced health monitoring or suspects you might benefit from these features, the Series 11 isn’t just nicer to have, it’s actually more capable in meaningful ways.
There’s a weird patent situation where the Series 11 can actually take blood oxygen readings but can’t display them on the watch itself. They only show up in your iPhone’s Health app. It’s a strange limitation, but it’s worth knowing.
The Series 11 also includes water-temperature and depth sensors, which matter if you’re swimming regularly. The SE 3 is water-resistant to 50 meters, but without those sensors, you’re missing information about what you’re actually doing in the water.
Fitness and Exercise: Closer Than You’d Think
For casual running, walking, hiking, and general fitness, both watches perform remarkably similarly. They both support the Vitals app, training load monitoring, noise monitoring, and GymKit compatibility. If your workout routine involves basic cardio and strength training, you honestly won’t feel shortchanged by the SE 3.
The real difference shows up if you’re in the pool frequently or doing longer workouts. The SE 3’s slightly smaller battery means you might squeeze fewer minutes out of it during extended exercise sessions. And again, that missing water-depth data on the SE 3 matters if swimming is part of your regular routine.
The health sensors on the Series 11 do give it an edge for serious fitness enthusiasts who want ECG readings and hypertension warnings. But here’s the thing: those are in the “nice to have” category for most people, even if they sound important in theory.
Sleep Tracking: Where the SE 3 Might Actually Be Better
This is the plot twist. The SE 3 is the lightest Apple Watch Apple makes, and that matters when you’re wearing it for eight hours while trying to sleep. It’s the least disruptive on your wrist at night, and since both watches offer the same sleep tracking features, the choice here genuinely comes down to comfort, appearance, and price.
If sleep is your primary metric for smartwatch usefulness, paying more for the Series 11 feels silly. Get the SE 3 and keep the $250.
Who Should Buy What
The Series 11 makes sense for people who want everything Apple offers, who are upgrading from an older watch (Series 7 or earlier), or who genuinely want those advanced health sensors. People upgrading from a Series 9 or 10? You’re probably going to be underwhelmed. The jumps aren’t that dramatic.
The SE 3 is the pick for kids and teens, for anyone on a tighter budget who won’t miss ECG readings and blood oxygen apps, and for people who just want a reliable smartwatch without paying premium prices. It’s not the “cheap” option because it’s somehow worse. It’s the practical option because it does most of what the expensive one does.
The real question you need to ask yourself is whether you’d actually use those advanced health features or if you’re just paying extra because they exist. Honestly? Most people buy the nicer watch and forget those features ever existed.
