Apple Watch Series 10 vs Apple Watch Ultra 3

Apple announced Series 10 on 9 September 2024 and Ultra 3 exactly a year later, on 9 September 2025, and the Health Sensing System has since arrived on Apple’s 2026 Series and Ultra models instead. That leaves two watches on the same S10 chip, separated by their cases, their batteries and their radios.

Side by side

Spec	Apple Watch Series 10	Apple Watch Ultra 3
Announced	9 September 2024	9 September 2025
Case	42 × 36 × 9.7mm or 46 × 39 × 9.7mm, aluminum or titanium	49 × 44 × 12mm, Grade 5 titanium
Weight, without band	Aluminum: 30 g or 36.4 g (GPS), 29.3 g or 35.3 g (cellular); titanium: 34.4 g or 41.7 g	61.6 g natural; 61.8 g black
Wrist fit	130–200mm (42mm); 140–245mm (46mm)	130–210mm
Display	Wide-angle LTPO3, up to 2,000 nits; 374 × 446 (989 sq mm) or 416 × 496 (1,220 sq mm)	LTPO3, up to 3,000 nits; 422 × 514 (1,245 sq mm)
Chip and storage	S10; 64GB	S10; 64GB
Normal use	Up to 18 hours	Up to 42 hours
Low Power Mode	Up to 36 hours	Up to 72 hours
Charge to 80%	About 30 minutes	About 45 minutes
GPS	L1	L1 and L5 dual-frequency
Cellular	LTE and UMTS	5G and LTE (A3281)
Satellite	No	SOS, Messages, Find My
Water	50 meters, shallow water	100 meters; scuba to 40 meters
Action Button and siren	No	Yes
US launch price	$399	$799

Thin everyday case, or the 49mm Ultra

On the wrist, Series 10 is the far smaller watch: 9.7mm thick against 12mm, and no more than 41.7 grams in any size or material, against 61.6 grams or more for Ultra 3. Apple lists the cellular aluminum models as slightly lighter than the GPS ones. Series 10 is also where Apple replaced stainless steel with Grade 5 titanium, in slate, gold or natural; aluminum comes in jet black, rose gold or silver.

Ultra 3’s flat sapphire screen is the brighter one, at 3,000 nits against 2,000, though both dim to 1 nit and both are 326 ppi. Apple says Series 10’s Always-On wide-angle OLED looks up to 40 percent brighter when you view it from an angle. Aluminum Series 10 models use Ion-X glass and titanium ones sapphire.

Ultra 3 adds an Action Button for Precision Start and other shortcuts, a siren and a flashlight, dual speakers with a three-microphone array, and Night Mode on the Modular Ultra, Wayfinder and Orienteering faces. Series 10 has a side button and Digital Crown instead.

Battery: 18 hours or 42

Series 10 is rated for up to 18 hours of normal use, or 36 in Low Power Mode, and it charges quickly: about 80% in 30 minutes, with fifteen minutes giving about eight hours of use and eight minutes about eight hours of sleep tracking. Expect to charge it every day.

Ultra 3 is rated for up to 42 hours, or 72 in Low Power Mode. It takes about 45 minutes to reach 80%, but fifteen minutes gives about 12 hours of normal use and five minutes about eight hours of sleep tracking. Apple gives neither watch a GPS workout rating, and Ultra 3 doesn’t offer Max Extended Workout; those longer workout ratings arrived with Ultra 4.

Satellite, diving and GPS

Ultra 3 is the one for places without cell coverage. It sends Emergency SOS, Messages and Find My over satellite, and its cellular model, A3281, has 5G and LTE. Its dual-frequency GPS uses both L1 and L5. It’s water resistant to 100 meters and rated for recreational scuba to 40 meters, with depth readings accurate to about 1 meter, a water temperature sensor, and dive apps that open automatically at about 1 meter. It’s IP6X dust resistant, tested to MIL-STD-810H, and rated for minus 20 to 55 degrees Celsius on the wrist.

Series 10 uses L1 GPS (with GLONASS, Galileo, QZSS and BeiDou) and LTE and UMTS for cellular. It’s water resistant to 50 meters for shallow swimming and snorkeling, not scuba, waterskiing or high-speed water. It has IP6X dust resistance, a depth gauge and a water temperature sensor, and Apple pointed snorkelers to Oceanic+, which needs a subscription, but it gives Series 10 no depth limit such as 6 meters and no MIL-STD rating. For safety it has Emergency SOS, international emergency calling, Crash Detection, Fall Detection, noise monitoring and Backtrack, but no satellite or siren. Apple rates it for 0 to 35 degrees Celsius and altitudes up to 3,000 meters.

The same once-a-second Always On

With your wrist down, both screens update once a second, so a seconds hand keeps moving. Series 10 brought that to the Series line and Ultra 3 to the Ultra line, replacing an update about once a minute, so it’s no reason to choose one over the other.

Health and sleep

Both have a third-generation optical heart sensor and an electrical sensor for ECG, with high and low heart rate alerts and irregular rhythm notifications. On Series 10, ECG is for people 22 and older where it’s available, Blood Oxygen is a wellness app, and a wrist temperature sensor joins the water sensor. Both offer sleep stages, plus sleep apnea notifications for people 18 and older (the feature runs on Series 9 or later and Ultra 2 or later).

Ultra 3 also lists a Sleep score and hypertension notifications, with region and age limits. Apple didn’t list either for Series 10 at launch, though later software brought some of those features to older watches. Neither watch has the Health Sensing System, and none of these features is a diagnosis.

Workouts and software

Series 10 has dedicated modes for running, hiking, cycling and swimming and a long list of others, from skiing and snowboarding to rowing, paddling and golf. Running gets training load, heart rate zones, Race Route and stride metrics, and hiking gets offline maps and curated hikes in 63 U.S. national parks. Ultra 3 has all of that plus a dedicated dive mode.

Both get watchOS 27. Series 10 shipped with watchOS 11 and asks for at least an iPhone Xs or iPhone SE (2nd generation) on iOS 18; Ultra 3 shipped with watchOS 26 and asks for an iPhone 11 or later on iOS 26 or later.

Bands, the box and materials

Each comes with one band and a Magnetic Fast Charger to USB-C. Series 10 uses the regular Apple Watch band fitting and Ultra 3 the Ultra fitting, so bands don’t swap. Both have Apple Pay and GymKit. Series 10 supports double tap and on-device Siri but not wrist flick; Ultra 3 has both gestures.

Apple says Series 10 can be carbon neutral when paired with certain bands and contains more than 30 percent recycled or renewable material, including recycled aluminum and titanium. It puts Ultra 3 at 40 percent recycled content, including recycled titanium in the case.

Price

Series 10 started at $399 for aluminum with GPS, with titanium and cellular models costing more; Ultra 3 started at $799. That $400 gap at launch, before bands or a cellular plan, paid for the 49mm case, the Action Button, satellite, dual-frequency GPS, 5G, the 100-meter rating and the 42-hour battery, not a better chip. Series 10 reached stores on 20 September 2024 and Ultra 3 on 19 September 2025; both are previous models now, so prices vary by seller and are worth checking before you buy.