The Apple Watch Series 12 is now available, three years after the Series 9. In that time, Apple has introduced a thinner design, larger displays, faster charging, new water sensors, and a substantially more capable health sensing system. Is that enough to justify replacing a Series 9?
Apple discontinued the Series 9 in 2024. The older watch still supports watchOS 27, so the decision comes down to the hardware and features you would gain. Here are the key 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 case
Aluminum, titanium, or ceramic case
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 Gold and Natural
Ceramic: Pearl White and Night 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 and sapphire crystal back
Case-matched metal or ceramic and zirconia back
41mm: 904 sq mm display area
45mm: 1,143 sq mm display area
42mm: 970 sq mm display area
46mm: 1,196 sq mm display area
LTPO OLED Always-On Retina display
LTPO3 wide-angle ?OLED? Always-On Retina display with a 1Hz refresh rate, enabling a live ticking seconds hand on select watch faces
S9 chip
S11 chip
2GB RAM
4GB RAM
Electrical heart sensor
Second-generation electrical heart sensor
Third-generation optical heart sensor
Fourth-generation, always-on 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 metrics
Vitals app with Recovery HRV and a daytime vitals view
Readiness app with a daily score and recommendation
Step tracking
Redesigned step tracking and a Steps watch face complication
Wrist temperature sensor
Wrist and water temperature sensors
Depth gauge 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 about 45 minutes
Up to 80% charge in about 30 minutes; 15 minutes of charging provides up to 12 hours of normal use
Now discontinued
From $399
Design
The Series 12 uses a similar version of the thinner design introduced with the Series 10. Its display area is about 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 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 the comparable aluminum GPS models are slightly heavier than their Series 9 counterparts. Buyers moving 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 meaningful cumulative upgrade, particularly if you use your watch for training and recovery. Its more frequent heart rate and HRV readings support Readiness, Recovery HRV, and daytime vitals, while the redesigned case provides a larger, squarer display with a more modern feel. The depth gauge and water temperature sensor also add useful information for swimmers and snorkelers.
Those improvements are less compelling if you mainly use your watch for notifications, everyday activity tracking, and occasional workouts. The Series 9 still has an always-on display, ECG, wrist temperature sensing, Double Tap, sleep apnea and hypertension notifications, and support for ?watchOS 27?. ?Siri? AI is also available on the Series 9 when paired with a compatible iPhone.
The Series 12 also has a slightly larger battery and charges faster, but likely not by enough to justify an upgrade alone. 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 in late 2026.
Which to Buy Today?
For a new purchase, the Series 12 is clearly the better choice. It offers three generations of accumulated improvements at the same $399 starting price the Series 9 had when new. The older model makes sense only at a substantial discount if you are satisfied with its existing health features.
A used or refurbished Series 9 can still be good value, but check its battery health, physical condition, and warranty before comparing prices. A worn battery could quickly erase the saving.Related Roundup: Apple Watch 12Buyer’s Guide: Apple Watch (Buy Now)Related Forum: Apple WatchThis article, “Apple Watch Series 9 vs. Series 12 Buyer’s Guide: Is It Worth Upgrading?” first appeared on MacRumors.comDiscuss this article in our forums
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Author: Hartley Charlton