Apple Watch Series 9 and Series 12 Buying Guide: Is It Worth Upgrading?
The Apple Watch Series 12 is now available, three years after Series 9. During this time, Apple has introduced a slimmer design, larger screens, faster charging, new water sensors and a significantly better health detection system. Is this enough to justify replacing a Series 9?
Apple discontinued the Series 9 in 2024. The older Watch still supports watchOS 27, so the decision depends on what hardware and features you’d gain. Here are the main differences between the Apple Watch Series 9 and Series 12:
| Apple Watch Series 9 | Apple Watch Series 12 |
|---|---|
| 41mm and 45mm cases, 10.7mm thick | 42mm and 46mm cases, 9.7mm thick in aluminum and titanium; ceramic cases are 9.85mm thick |
| Aluminum or stainless steel housing | Aluminum, titanium or ceramic housing |
| Aluminum: Silver, Starlight, Midnight, Pink and (PRODUCT)RED | Aluminum: Dark Bronze, Light Gold, Black and Space Gray |
| Stainless steel: Silver, Gold and Graphite | Titanium: Radiant and Natural Gold Ceramic: Pearl White and Midnight Blue |
| Ion-X front glass on aluminum models; sapphire crystal on stainless steel models | Ceramic Shield 2 on aluminum models; sapphire crystal on titanium and ceramic models |
| Ceramic back and sapphire crystal | Back in metal or ceramic and zirconia matching the case |
| 41mm: 904 mm² display surface 45mm: 1,143 mm² of exhibition surface |
42mm: 970 mm² display surface 46mm: 1,196 mm² of exhibition surface |
| Always-on Retina display LTPO OLED | Always-on LTPO3 wide-angle OLED Retina display with a 1Hz refresh rate, enabling a live second hand on select watch faces |
| S9 chip | S11 chip |
| 2 GB of RAM | 4 GB of RAM |
| Electric heart sensor | Second generation electrical heart sensor |
| Third generation optical heart sensor | Fourth generation permanent optical heart sensor |
| Periodic background heart rate readings | Background heart rate readings every five seconds |
| Heart rate variability (HRV) measurements | Recovery HRV and overall HRV, measured up to 24 times more frequently |
| Vitals app with overnight health measurements | Vitals app with Recovery HRV and view of vital signs during the day |
| Preparation app with daily score and recommendations | |
| Tracking steps | Redesigned step tracking and Steps watch face complication |
| Wrist temperature sensor | Wrist and water temperature sensors |
| Depth gauge up to 6 meters and depth app | |
| Microphone | Microphone with voice isolation |
| Speaker | Redesigned speaker with media playback |
| Audio intelligence, including sound recognition, faster Shazam, Live Rewind and Siri Recap | |
| LTE and UMTS on cellular models | LTE and 5G RedCap on cellular models |
| Up to 18 hours of normal use; up to 36 hours in low power mode | Up to 24 hours of normal use; up to 38 hours in low power mode |
| Up to 80% charge in approximately 45 minutes | Up to 80% charge in approximately 30 minutes; 15 minutes of charging provides up to 12 hours of normal use |
| Now abandoned | From $399 |
Design
The Series 12 uses a similar version of the slimmer design introduced with the Series 10. Its display area is approximately 7% larger in the smaller size and 5% larger in the larger size than the corresponding Series 9 models. The Series 12 figures below are for the aluminum models; its ceramic cases are slightly larger and heavier:
| Apple Watch Series 9 | Apple Watch Series 12 | |
|---|---|---|
| Smaller case | 41mm × 35mm × 10.7mm | 42mm × 37mm × 9.7mm |
| Larger case | 45mm × 38mm × 10.7mm | 46mm × 40mm × 9.7mm |
| Smaller aluminum model, GPS | 31.9 grams | 32.2 grams |
| Larger aluminum model, GPS | 38.7 grams | 39.5 grams |
| Smaller aluminum model, cellular | 32.1 grams | 31.5 grams |
| Larger aluminum model, cellular | 39.0 grams | 38.6 grams |
The Series 12 is noticeably thinner, but comparable aluminum GPS models are slightly heavier than their Series 9 counterparts. Buyers upgrading from a stainless steel Series 9 to a titanium Series 12 will see a more substantial weight reduction because the case material has changed.
Is it worth upgrading?
For Series 9 owners, the Series 12 is a significant cumulative upgrade, especially if you use your watch for training and recovery. Its more frequent heart rate and HRV readings support readiness, recovery and daytime vitals, while the redesigned case offers a larger, squarer screen with a more modern feel. The depth gauge and water temperature sensor also add useful information for swimmers and snorkelers.
These improvements are less compelling if you primarily use your watch for notifications, daily activity tracking, and occasional workouts. The Series 9 still has an always-on display, ECG, wrist temperature detection, double tap, sleep apnea and hypertension notifications, and support for watchOS 27. Siri AI is also available on Series 9 when paired with a compatible iPhone.
The 12 Series also has a slightly larger battery and charges faster, but probably not enough to warrant an upgrade on its own. The Series 12’s audio intelligence features may strengthen the case for some users, especially sound recognition for people who are deaf or hard of hearing. Live Rewind and Siri Recap will arrive in beta at the end of 2026.
Which one to buy today?
For a new purchase, the Series 12 is clearly the best choice. It offers three generations of accumulated improvements at the same $399 starting price that the Series 9 had when it was new. The old model only makes sense at a substantial discount if you are happy with its existing health features.
A used or refurbished Series 9 can still be good value, but check its battery condition, physical condition, and warranty before comparing prices. A worn-out battery could quickly wipe out the savings.
