Apple Watch Series 12 vs Apple Watch Ultra 4

Apple announced both on 9 September 2026 and put both in stores on 18 September 2026, after taking pre-orders on announcement day. Both ship with watchOS 27 and pair with an iPhone 11 or later, including iPhone SE (2nd generation or later), on iOS 27. The difference is in what you strap on: a 46mm aluminum Series 12 is 9.7mm thick and weighs 39.5 grams, while Ultra 4 is 12mm thick and weighs 63.0 grams.

Side by side

Spec	Apple Watch Series 12	Apple Watch Ultra 4
Sizes	42mm or 46mm	49mm only
Case	Aluminum, titanium or ceramic	Grade 5 titanium
Thickness	9.7mm aluminum and titanium; 9.85mm ceramic	12mm
Weight	39.5 g (46mm aluminum GPS)	63.0 g natural; 63.1 g black
Display	LTPO3, up to 2,000 nits, 1Hz Always On	LTPO3, up to 3,000 nits, 1Hz Always On
Pixels	374 × 446 or 416 × 496	422 × 514
Chip and storage	S11; 64GB	S11; 64GB
Heart sensors	Health Sensing System	Health Sensing System
Normal use	Up to 24 hours	Up to 50 hours
Low Power Mode	Up to 38 hours	Up to 84 hours
GPS workouts	Up to 10 hours outdoors	18 hours; 25 Extended; 45 Max Extended
Charge to 80%	About 30 minutes	About 45 minutes
GPS	Precision L1	Precision dual-frequency
Water	50m; snorkeling to 6m	100m; recreational dives to 40m
Satellite	No	SOS, Messages, Find My
Action Button and siren	No	Yes
US launch price	$399	$799

Battery: more than twice the hours, slower to fill

Series 12 is rated for up to 24 hours of normal use and 38 in Low Power Mode. Its outdoor-workout rating is up to 10 hours, which Apple says is 25 percent more than the previous Series, measured on an outdoor run with the heart-rate sensor on and no iPhone nearby.

Ultra 4 is rated for up to 50 hours of normal use and 84 in Low Power Mode, and it gets three GPS workout ratings: 18 hours outdoors, 25 in Extended Workout and 45 in Max Extended Workout, a mode for long runs, walks and hikes that still takes a GPS fix every second.

Charging flips the picture. Series 12 reaches about 80 percent in about 30 minutes on its magnetic fast charger (Apple’s charging tests used model A3277), while Ultra 4 takes about 45. Short top-ups favor the Ultra: fifteen minutes buys about 18 hours of normal use on Ultra 4 against about 12 on Series 12, and five minutes buys about 10 hours of sleep tracking on either watch.

If your day fits inside 24 hours and the watch charges on your nightstand, Series 12’s battery won’t hold you back. If you want to skip a night on the charger, or keep GPS running through a long hike, that’s what the Ultra’s extra money buys. Neither one is a week-long GPS watch.

Satellite, scuba and better GPS are Ultra-only

With no cell signal, Ultra 4 can still send Emergency SOS, Messages and Find My over satellite. Series 12 can’t. Its safety list covers Emergency SOS, international emergency calling, Fall Detection, Crash Detection and Check In, plus a flashlight, but there’s no siren and no Action Button.

GPS splits the same way. Series 12 has precision L1 GPS, working with GPS, GLONASS, Galileo, QZSS and BeiDou. Ultra 4 has precision dual-frequency GPS with GPS, Galileo, QZSS and BeiDou, which Apple calls the most accurate on-device GPS in a sports watch. That’s Apple’s claim, and Apple keeps dual-frequency for the Ultra.

Water is the biggest practical gap. Series 12 is water resistant to 50 meters under ISO 22810, fine for swimming and snorkeling to 6 meters but not for scuba or high-velocity water sports, and its depth gauge stops at 6 meters. Ultra 4 is rated to 100 meters and certified to EN 13319 for recreational dives to 40 meters, with depth readings accurate to about 1 meter. Dive apps, including Oceanic+ from the App Store, open automatically once you pass 1 meter.

Both are IP6X dust-resistant. Ultra 4 is also tested against a list of MIL-STD-810H methods and rated for minus 20 to 55 degrees Celsius on the wrist and altitudes up to 9,000 meters; Apple doesn’t give Series 12 a comparable operating range. Series 12’s toughness claim is about glass: aluminum models get Ceramic Shield 2, which Apple says is tougher than any other smartwatch glass and 60 percent tougher than the Ion-X glass on Series 11.

Health tracking is identical

Don’t pay Ultra money for health features. Both watches have the Health Sensing System, with a second-generation electrical heart sensor and an always-on optical heart sensor, plus Blood Oxygen and temperature sensing. Both check your heart rate in the background every five seconds and sample heart rate variability as often as every five minutes. Apple’s headline multipliers, 60× and 24×, compare each watch with its own predecessor (Ultra 3 and the previous Series), not with each other.

Both get the daily readiness score, a Sleep score, and sleep apnea notifications where Apple offers them. ECG and Blood Oxygen depend on your region, and none of these features is a diagnosis.

Both also get Audio Intelligence on S11: Live Rewind, Siri Recap, Shazam and Sound Recognition. Live Rewind and Siri Recap are betas due in late 2026, starting in English and not available in the EU at launch. The redesigned Health app with Health Age follows later in 2026, in U.S. English first.

The controls differ only slightly. Series 12 has single tap, double tap and wrist flick, plus a single-handed tap that opens a Smart Stack widget. Ultra 4 has the same three gestures and adds the Action Button.

Size, weight and the ceramic option

Series 12’s aluminum and titanium cases measure 42 × 37 × 9.7mm or 46 × 40 × 9.7mm. The ceramic models are sold as 42mm and 46mm but measure 43 × 37 × 9.85mm and 47 × 41 × 9.85mm. The screens are 374 × 446 pixels on the smaller size and 416 × 496 on the larger, both at 326 ppi, with 970 and 1,196 square millimeters of active area, and they range from 2,000 nits down to 1 nit. The 42mm fits wrists from 130 to 200mm, the 46mm from 140 to 245mm.

Weights, for the case alone, depend on the material. On the 46mm, aluminum GPS weighs 39.5 grams and, oddly, the cellular aluminum model is lighter at 38.6 grams. Titanium is 44.9 grams, pearl white ceramic 51.3 grams and night blue ceramic 52.9 grams, so the ceramic case outweighs titanium but still comes in under the Ultra.

Ultra 4 comes in one size: 49 × 44 × 12mm and 63.0 or 63.1 grams, for wrists from 130 to 210mm. Its 422 × 514 screen peaks at 3,000 nits under sapphire. Both watches refresh Always On once a second (1Hz), so a ticking seconds hand isn’t an Ultra perk.

Cellular, bands and the rest

Cellular Series 12 models (A3582 and A3587) and Ultra 4’s cellular model (A3579) all have 5G RedCap and LTE, with international roaming. Both watches have Wi-Fi 4 on 2.4GHz and 5GHz, Bluetooth 5.3, a second-generation ultra-wideband chip, Apple Pay and GymKit.

Bands don’t cross over. Series 12 uses the standard Apple Watch band fitting, with this year’s Sport Band, Sport Loop, Nike, Milanese and Modern Buckle; ceramic models come with ceramic pin-and-tuck Sport Bands. Ultra 4 uses the Ultra fitting, and its 2026 sport bands are the Trail Loop, Alpine Loop and Ocean Band.

Price

Series 12 starts at $399 in the US for the aluminum GPS model; titanium, ceramic and cellular versions cost more. Ultra 4 starts at $799. With the chip and the health sensors shared, the $400 difference pays for the case, the outdoor hardware and the battery. Prices move after launch, so check apple.com before you buy.