The Apple Watch Series 12 starts at $399 and the Apple Watch SE 3 at $249, a $150 gap. Apple’s tech specs and compare page show what that money buys: the S11 chip instead of S10, a 2000-nit display instead of 1000, 24 hours of battery instead of 18, a 30-minute fast charge instead of 45, larger 42 mm and 46 mm cases, and a sensor list that includes electrical heart and Blood Oxygen sensors the SE 3 does not have.
The SE 3 was not updated on September 9, so it stays the entry watch while Series 12 replaces Series 11. It did briefly disappear from Apple’s store before the event, as we noted in our SE 3 availability story, but it is back at the same From $249 price. Every SE 3 figure below comes from Apple’s SE 3 tech specs or Apple’s compare page.
Series 12 vs SE 3 spec table
| Spec | Apple Watch Series 12 | Apple Watch SE 3 |
|---|---|---|
| Price | From $399 | From $249 |
| Case sizes | 42 mm, 46 mm | 40 mm, 44 mm |
| Materials | Aluminum, titanium, ceramic | Aluminum (Starlight, Midnight) |
| Depth | 9.7 mm (9.85 mm ceramic) | 10.7 mm |
| Weight (aluminum GPS) | 32.2 g / 39.5 g | 26.3 g / 32.9 g |
| Peak brightness | 2000 nits | 1000 nits |
| Chip | S11 | S10 |
| Storage | 64GB | 64GB |
| Battery, normal use | Up to 24 hours | Up to 18 hours |
| Low Power Mode | Up to 38 hours | Up to 32 hours |
| Fast charge to 80 percent | About 30 minutes | About 45 minutes |
| Water resistance | 50 m | 50 m |
| 5G (cellular models) | Yes | Yes |
| Satellite | No | No |
Some things are the same. Both watches have 64GB of storage, a 50 m water rating, 5G on cellular models, Wi-Fi 4, Bluetooth 5.3 and a second-generation Ultra Wideband chip. Neither has satellite connectivity, which stays with the Ultra 4.
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Display and case: 2000 nits vs 1000 nits
The most visible difference is brightness. Series 12 peaks at 2000 nits on an LTPO3 wide-angle OLED that refreshes down to 1 Hz for Always-On. Apple’s compare page lists the SE 3 at 1000 nits. Series 12 also comes in bigger cases, 42 mm and 46 mm against 40 mm and 44 mm, and is thinner at 9.7 mm versus 10.7 mm.
Series 12 is the only one of the two with a choice of materials. Aluminum models get Ceramic Shield 2 in Dark Bronze, Light Gold, Black and Space Gray; titanium and ceramic models get sapphire crystal. The SE 3 is aluminum only, in Starlight and Midnight. On weight, the SE 3 is lighter: 26.3 g for the 40 mm and 32.9 g for the 44 mm, against 32.2 g and 39.5 g for the aluminum Series 12.
Health sensors: what the SE 3 leaves out
This is where the $150 does most of its work. Series 12 has Apple’s new Health Sensing System with a third-generation electrical heart sensor, an always-on optical heart sensor, Blood Oxygen and temperature sensors, and a depth gauge to 6 meters. Apple says heart rate is measured every five seconds and HRV every five minutes, feeding the new Readiness app.
Apple’s pages differ on the SE 3. The compare page fetch listed ECG and Blood Oxygen as available on every current watch, but Apple’s SE 3 tech specs list neither an electrical heart sensor nor a Blood Oxygen sensor, so treat those two features as Series 12 only. The compare page does list hypertension notifications and sleep score for both watches.
Battery: 24 hours vs 18 hours, and faster charging
Apple rates Series 12 at up to 24 hours of normal use and 38 hours in Low Power Mode. The SE 3 is rated at 18 hours and 32 hours. Series 12 also charges faster: about 30 minutes to 80 percent, with a 15-minute top-up good for up to 12 hours. The SE 3 takes about 45 minutes to reach 80 percent, and Apple has not published a 15-minute figure for it on the pages we checked.
Series 12 adds an outdoor workout rating of up to 10 hours. Apple has not published an equivalent SE 3 figure.
Which one to buy
If you want ECG, Blood Oxygen, a brighter screen, a full day plus of battery and the option of titanium or ceramic, Series 12 is the watch, and our Series 12 launch story covers the rest of what is new. If you mainly want notifications, workouts, Apple Pay and the same watchOS 27 features at the lowest price, the SE 3 does that for $150 less and weighs less doing it.
Both run watchOS 27 with an iPhone 11 or later on iOS 27. Series 12 pre-orders are open, with availability September 18; the SE 3 is available now. Apple has not published per-configuration prices for Series 12 titanium, ceramic or cellular models, so the real gap can be larger than $150 once you move past the base aluminum.
