Apple Watch SE 3 vs. Series 12 Buyer's Guide: Which Should You Buy?

The Apple Watch SE 3 and Series 12 are two models of smartwatches from Apple, each offering a unique set of features and capabilities. The SE 3 starts at $249, while the Series 12 begins at $399, a $150 price difference that grants the more advanced Series 12 several enhancements. These include a superior health sensing system, a larger display, extended battery life, and additional tracking options for exercise and recovery.

Despite these differences, both watches share many common features such as an always-on display, wrist temperature sensing, sleep apnea notifications, retrospective ovulation estimates, 5G connectivity on cellular models, media playback, and 64GB of storage.

The design of the SE 3 mirrors that of the Series 4, 5, and 6, with a refined aesthetic featuring a thinner casing, more rounded edges, and a wider aspect ratio display. The front glass also extends further over the sides, resulting in a higher screen-to-body ratio. The case options vary between aluminum, titanium, or ceramic, with case sizes available in 40mm, 44mm, 42mm, and 46mm for aluminum/titanium models, and 42mm, 46mm, 43mm, and 47mm for ceramic models.

The weight of the GPS models ranges from 26.3 grams to 39.5 grams, depending on the material. Both models utilize different types of glass; the SE 3 features Ion-X front glass, while the Series 12 employs Ceramic Shield 2, with certain models featuring a sapphire crystal front.

In terms of display, the SE 3 is equipped with an LTPO OLED display, while the Series 12 boasts an LTPO3 display with a 1Hz always-on refresh rate, including a live ticking seconds hand on certain watch faces. The display resolutions also differ, with the SE 3 offering 324 by 394 pixels on the 40mm model and 416 by 496 pixels on the 46mm model, while the Series 12 provides 759 square millimeters on the 40mm model and up to 1,196 square millimeters on the 46mm model, with brightness levels reaching up to 2,000 nits.

Power consumption is managed with minimum brightness settings of 1 nit for the SE 3 and 2 nits for the Series 12.

The SE 3 is powered by the S10 chip released in 2024, while the Series 12 incorporates the S11 chip launched in 2026, granting it a superior processing capability. Both models come with 2GB of RAM for the SE 3 and 4GB of RAM for the Series 12. The SE 3 utilizes a second-generation optical heart sensor, always-on optical heart sensor, and standard background heart rate tracking.

In contrast, the Series 12 offers advanced heart rate monitoring, heart rate variability tracking, and more frequent overall HRV readings. The Vitals app on the Series 12 provides additional health metrics, including heart rate, respiratory rate, wrist temperature, and sleep duration.

The Series 12 also includes the Readiness app, which incorporates electrical heart sensors and ECG functionality. Blood oxygen monitoring is available through both devices, aiding users in tracking their overall health. Hypertension notifications are standard on the Series 12, while the SE 3 offers basic step tracking improvements along with real-time heart rate and step tracking watch face complications.

The Series 12 introduces water resistance ratings to 6 meters, access to the Oceanic+ app for snorkeling, and audio intelligence features like Siri Recap, Sound Recognition, Shazam, and Live Rewind. The microphone quality also differs, with the SE 3 featuring a single elongated speaker opening and the Series 12 providing individual speaker holes.

Connectivity options are enhanced in the Series 12, offering 2.4GHz and 5GHz Wi-Fi 4, L1 GPS Precision, and HomePod playback controls compatible with Ultra Wideband. The SE 3 supports up to 18 hours of normal use, while the Series 12 can operate for up to 24 hours under normal conditions, extending to 32 hours in Low Power Mode.

Charging times vary, with the SE 3 charging from 0 to 80% in about 45 minutes and the Series 12 completing the same task in approximately 30 minutes. For sleep tracking, the SE 3 requires 15 minutes of charging for up to 8 hours, and the Series 12 provides a faster charge for up to 10 hours. Unique finishes such as Midnight and Starlight aluminum, Dark Bronze, Light Gold, Black, Space Gray, Radiant Gold, Natural titanium, Pearl White, Night Blue ceramics, and Hermès models are exclusive to the Series 12.

Starting prices for the Series 12 begin at $699 for titanium models and $899 for ceramic models, reflecting its premium features and capabilities.