Apple Watch Ultra 4 vs Apple Watch Ultra 3

Apple released these a year apart, on 9 September 2025 and 9 September 2026, at the same $799 starting price, and on a wrist you can’t tell them apart. Everything that separates them is inside the case.

The differences at a glance

Spec	Apple Watch Ultra 4	Apple Watch Ultra 3
Announced	9 September 2026	9 September 2025
Case	49 × 44 × 12mm Grade 5 titanium	Same
Weight	63.0 g natural; 63.1 g black	61.6 g natural; 61.8 g black
Display	LTPO3, 422 × 514, 3,000 nits, 1Hz Always On	Same
Chip / storage	S11; 64GB	S10; 64GB
Normal use	Up to 50 hours	Up to 42 hours
Low Power Mode	Up to 84 hours	Up to 72 hours
GPS workouts	18 hours; 25 Extended; 45 Max Extended	No workout rating given
Charging	80% in about 45 minutes	80% in about 45 minutes
GPS	Dual-frequency (GPS, Galileo, QZSS, BeiDou)	L1+L5 (GPS, GLONASS, Galileo, QZSS, BeiDou)
Satellite	SOS, Messages, Find My	Same three, free for two years after activation
Heart sensors	Health Sensing System	Third-generation optical + electrical
iPhone needed	iPhone 11 or later, iOS 27	iPhone 11 or later, iOS 26 at launch
US launch price	$799	$799

The new heart sensors are the real upgrade

Ultra 4’s Health Sensing System is new hardware: redesigned optical and electrical heart sensors with bigger green LEDs, driven by S11. Ultra 3 can’t get it in a software update.

Heart rate. Ultra 4 checks your heart rate in the background every five seconds, all day. Apple calls that 60× more often than Ultra 3, which works out to about once every five minutes on the older watch.

HRV. Heart rate variability is sampled as often as every five minutes, which Apple calls 24× more often, or about once every two hours on Ultra 3. Both Recovery HRV and overall HRV show up in Vitals and the Heart Rate app.

Readiness. Only Ultra 4 has it: a 0–10 score each morning with a one-word call (Recover, Pace Yourself, Ready or Go For It), built from your recent activity, training load, vitals and sleep, and updated through the day. If you want a push-or-rest signal without reading charts, this is the feature you’re paying for.

Ultra 3 isn’t short on health features. It has the third-generation optical sensor and the electrical sensor, plus ECG, Blood Oxygen, wrist and water temperature, sleep stages, a Sleep score, and sleep apnea and hypertension notifications. ECG, Blood Oxygen, sleep apnea and hypertension features depend on your country on both watches, and none of them is a diagnosis.

Ultra 4 also gets Audio Intelligence on S11 (Live Rewind, Siri Recap, Shazam and Sound Recognition) and adds a single-tap gesture to the double tap and wrist flick both watches have.

Battery: eight more hours, and real GPS ratings

Mode	Ultra 4	Ultra 3
Normal use	Up to 50 hours	Up to 42 hours
Low Power Mode	Up to 84 hours	Up to 72 hours
Outdoor workout	Up to 18 hours	No rating given
Extended Workout	Up to 25 hours	No rating given
Max Extended Workout	Up to 45 hours	Not offered

Max Extended Workout covers outdoor running, walking and hiking with GPS checking your position every second; Apple’s example is a 100-mile race. It doesn’t apply to every sport the watch tracks. If you’re replacing Ultra 3 for long days on a trail, the workout ratings are the reason. If your days look like Apple’s normal-use test, the gap is 50 hours against 42.

Both charge to about 80% in 45 minutes on the magnetic fast charger. Short top-ups go further on Ultra 4: 15 minutes is about 18 hours of normal use against 12, and 5 minutes is about 10 hours of sleep tracking against 8.

Ultra 4 weighs about a gram and a half more. Both cases are 49 by 44 by 12 millimeters and fit wrists from 130 to 210 millimeters, in natural or black titanium. Hermès Ultra 4 is a separate collection, not the $799 model.

Same screen, same Always On

The display didn’t change: LTPO3, 422 × 514 pixels, 3,000 nits peak, and an Always On mode that refreshes once a second (1Hz). Ultra 3 introduced that faster Always On; older Ultras updated about once a minute. A ticking seconds hand with your wrist down is something both watches do, so it’s no reason to upgrade.

Satellite, diving and GPS are a wash

If satellite is why you bought Ultra 3, you already have it. Both send Emergency SOS, Messages and Find My over satellite. Apple’s Ultra 3 terms include two years free after activation; Ultra 4’s spec sheet lists the same features without repeating the offer, so check the terms that come with the watch you buy.

The rest of the outdoor kit matches. Both have the Action Button, siren, flashlight, depth gauge and water-temperature sensor, and both are certified to EN 13319 for recreational dives to 40 meters with about 1 meter of depth accuracy. Dive apps open automatically at 1 meter (Oceanic+ on Ultra 4, any App Store dive computer on Ultra 3), and GPS marks where you entered and left the water. Both are water resistant to 100 meters under ISO 22810, IP6X dust-rated, and tested against the same list of MIL-STD-810H methods.

Both use precision dual-frequency GPS. Ultra 3 also lists GLONASS; Ultra 4 lists GPS, Galileo, QZSS and BeiDou. Apple calls Ultra 4’s positioning the most accurate on-device GPS in a sports watch, which is its claim. Hiking tools match: compass, waypoints, Backtrack, offline maps, U.S. topographic maps and curated hikes in all 63 U.S. national parks. So do the running metrics: cadence, stride length, ground contact time, vertical oscillation, running power and Precision Start on the Action Button.

Both are cellular, with 5G RedCap and LTE (model A3579 for Ultra 4, A3281 for Ultra 3), and both have Wi-Fi 4, Bluetooth 5.3 and a second-generation ultra-wideband chip. Apple rates both for minus 20 to 55 degrees Celsius on the wrist, 0 to 40 degrees for diving, and altitudes from minus 500 to 9,000 meters.

Software won’t decide it

Ultra 4 ships with watchOS 27 and needs an iPhone 11 or later, including iPhone SE (2nd generation or later), on iOS 27. Ultra 3 launched on watchOS 26 with iOS 26, and it’s on Apple’s watchOS 27 list (Ultra 2 or later), which also needs iOS 27. You don’t need Ultra 4 to get the new watchOS.

Apple’s recycled-content figures differ slightly: 45% for Ultra 4, including all of the titanium in the case, 100% recycled cobalt and 95% recycled lithium in the battery, against 40% for Ultra 3, also with all-recycled titanium.

What they cost

Both started at $799 in the US. Ultra 4 pre-orders opened 9 September 2026 and it reached stores on 18 September 2026; Ultra 3 reached stores on 19 September 2025 and is now the previous model. A discounted Ultra 3 makes sense only when the gap is big enough to give up the sensors and the extra battery. Prices move, so check apple.com before you buy.

Each box has the watch, one band and a one-meter magnetic fast charger to USB-C. Ultra 4’s sport bands this year are the Trail Loop, Alpine Loop and a translucent Ocean Band; which one you get depends on the configuration.