Apple Watch Ultra 4 vs Ultra 3: 50 hours and new sensors

In comparison, Apple Watch Ultra 4 vs Ultra 3, two things matter: battery and sensors. Ultra 4 lasts up to 50 hours instead of 42, and the new health measurement system checks heart rate every 5 seconds around the clock and calculates the Readiness index from that. The screen, case dimensions, satellite, and diving features remain unchanged.

The watch went on sale on September 18, 2026, and in Poland, it costs 3,799 PLN, exactly the same amount that Ultra 3 cost at launch last year.

There is also one very good piece of news that no presentation mentions: the case has not grown by a millimeter. Ultra 4 has the same dimensions of 49 × 44 × 12 mm as Ultra 3, Ultra 2, and the first Apple Watch Ultra from four years ago.

A short answer on who should choose what: Ultra 4 for first-time buyers and for those upgrading from older than Ultra 3, Ultra 3 on sale if you count every penny. Owners of Ultra 3 have no reason to change.

Below is the full table of both models, a fair list of things that Ultra 4 does not improve at all, and a specific answer to the question of whether your existing bands and cases will fit the new watch.

On the left Apple Watch Ultra 4, on the right Ultra 3. The case 49 × 44 × 12 mm is identical in both. Photos: Apple.

Apple Watch Ultra 4 vs Ultra 3: complete comparison table

We have bolded only those items that actually differ.

Parameter	Apple Watch Ultra 3	Apple Watch Ultra 4
Release	September 2025	September 18, 2026
Chip	S10	S11
Storage	64 GB	64 GB
Optical heart rate sensor	3rd generation	redesigned, Health Sensing System
Electrical sensor (ECG)	previous generation	larger electrode surface
Heart rate measurement recording	samples every few minutes	sample every 5 seconds, 24/7
HRV measurement	standard frequency	up to 24 times more frequently
Readiness	❌	✅
Audio Intelligence	❌	✅
Display	LTPO3 wide-angle OLED, always-on	LTPO3 wide-angle OLED, always-on
Resolution	422 × 514	422 × 514
Screen area	1,245 mm²	1,245 mm²
Peak brightness	3,000 nits	3,000 nits
Glass	flat sapphire	flat sapphire
Case material	Grade 5 titanium	Grade 5 titanium, 3D printed
Colors	natural titanium, black titanium	natural titanium, black titanium
Dimensions	49 × 44 × 12 mm	49 × 44 × 12 mm
Weight natural / black	61.6 g / 61.8 g	63.0 g / 63.1 g
Battery, normal use	up to 42 hours	up to 50 hours
Low power mode	up to 72 hours	up to 84 hours
Outdoor training	no data in specifications	up to 18 hours
Extended training	no data in specifications	up to 25 hours
Maximum extended training	no data in specifications	up to 45 hours
15 minutes of charging provides	up to 12 hours of use	up to 18 hours of use
Charging to 80%	approx. 45 minutes	approx. 45 minutes
Cellular network	5G RedCap and LTE	5G RedCap and LTE
Satellite connectivity	✅	✅
Wi-Fi / Bluetooth	Wi-Fi 4 / Bluetooth 5.3	Wi-Fi 4 / Bluetooth 5.3
GPS	dual-frequency L1 and L5	dual-frequency L1 and L5
Ultra Wideband	2nd generation	2nd generation
Water resistance	100 m, IP6X	100 m, IP6X
Diving EN13319	up to 40 m	up to 40 m
Requirements	iPhone 11+, iOS 26	iPhone 11+, iOS 27
Starting price in Poland	3,799 PLN	3,799 PLN

Thirty-four positions, of which fourteen differ. More importantly: aside from 1.4 grams of weight, all differences lie in the battery, sensors, and software. The dimensions of the case and screen remain untouched.

Accessories for both generations are readily available, as the cut hasn’t changed. See bands and cases for the Apple Watch Ultra 49 mm →

Battery: eight hours more and faster charging

This is the most measurable change in the entire launch. The Ultra 3 claimed 42 hours of normal usage, while the Ultra 4 states 50 hours. In Low Power mode, the jump is similar: from 72 to 84 hours.

What does this mean in practice? The Ultra 3 usually drained by the end of the second day, so you realistically charged it every other evening. The Ultra 4 easily lasts two full days with sleep tracking in between and leaves enough for a morning workout on the third day.

The second gain is even more practical. 15 minutes of charging provides 18 hours of use instead of 12. A quarter of an hour in the shower is enough to leave the house with the watch for the whole day and night.

• Normal use: 50 hours instead of 42, which is 19% longer
• Low energy consumption: 84 hours instead of 72
• Outdoor training with GPS and heart rate: up to 18 hours in Ultra 4
• Extended training: up to 25 hours in Ultra 4
• Maximum extended training with GPS every second: up to 45 hours in Ultra 4
• Charging to 80%: about 45 minutes in both models

Note the last line. Apple did not change the full charging speeds, only what it provides in a quarter of an hour. For the Ultra 3, the manufacturer does not publish separate results for outdoor training and extended mode, so these two items cannot be fairly compared.

You won’t find chargers in the box of either of these models. If you need a second one for your desk or travel, choose it from the inductive chargers category.

New health measurement system, or the second half of this launch

Apple calls it the Health Sensing System and it is not a marketing label for the same electronics. Both sensors on the bottom of the case have physically changed.

Apple explicitly mentions a new optical sensor and a new electrical sensor, which are both systems responsible for heart rate and ECG. Details of the construction, such as larger LEDs or different arrangements of photodiodes, are described by industry services; the manufacturer does not provide them in the specifications. The same set of sensors has also been introduced to the Apple Watch Series 12.

Heart rate every 5 seconds instead of samples every few minutes

Apple had not previously stated how often the Ultra 3 measures heart rate in the background. For the Ultra 4, it declares it directly: readings every 5 seconds around the clock, which is about 17 thousand times a day.

Why so much? Because from denser data, you can calculate things that are not visible in sparse samples: stress response, micro fluctuations in heart rate after coffee, recovery pace after intervals.

HRV measured 24 times more often and the Readiness indicator

Heart Rate Variability (HRV) is a parameter that tells you whether the body has actually rested. The Ultra 4 measures it up to 24 times more often than its predecessor and separates it into recovery HRV and overall HRV.

This is the basis for Readiness, a score on a scale from 0 to 10 that you receive in the morning along with one of four recommendations: recover, pace yourself, you are ready, or go full throttle.

Note: Apple makes the Ready feature available only on Ultra 4 and Series 12 and has not announced it for older models. The feature relies on measurement density that the sensor from Ultra 3 simply does not collect.

If you train according to loads and realistically look at recovery, this is the reason to change your watch. If the Ultra is primarily a durable watch with satellite for you, you won’t notice the difference.

Audio Intelligence, or what the watch does with sound

This is a set of four features that Ultra 3 will not receive: Sound Recognition (alarm, baby crying, siren), faster Shazam, Live Rewind (displaying the last 15 seconds of a conversation as text after double-clicking the crown), and Siri Recap (summary of the conversation).

The first two have been available since launch. Live Rewind and Siri Recap require an iPhone with Apple Intelligence and are being rolled out in stages. Apple requires Series 12 or Ultra 4 for them, so it is not exclusive to the Ultra model, but older watches will not receive them.

What Apple Watch Ultra 4 Does Not Improve

An honest list of things that remain exactly the same. For the Ultra model, it is exceptionally long, as its predecessor set the bar very high.

• Display: 422 × 514 pixels, 1,245 mm² surface area, and 3,000 nits brightness, unchanged
• Sapphire glass in a flat version, identical in both models
• Case: the same 49 × 44 × 12 mm and the same Grade 5 titanium
• Satellite connectivity: SOS Alarm, messages, and Find are available on both models
• 5G RedCap and LTE, no differences
• Dual-frequency GPS L1 and L5, the same setup
• Diving: 100 m water resistance and EN13319 up to 40 m in both
• Three beamforming microphones, two speakers, and a siren, identical
• 64 GB memory and 2nd generation Ultra Wideband, unchanged

There is also no glucose level measurement, which is rumored every year. There is no change in the shape of the case or a new strap attachment system.

However, the Ultra 4 is 1.4 grams heavier (63.0 g compared to 61.6 g in natural titanium). It’s a difference you won’t feel on your wrist, but it’s worth knowing that the newer generation has gained a little weight, despite identical dimensions.

Unofficially, there are also 4 GB of RAM, as reported by 9to5Mac. Apple does not provide this parameter in the specifications, so treat it as second-hand information.

Apple Watch Ultra 4 Price: how much it costs in Poland

The entry price has not changed. Apple Watch Ultra 4 costs 3,799 PLN in the version with natural or black titanium, always with GPS and cellular modem. Exactly the same price as Ultra 3 at the time of its release.

Ultra 3 has made way for its successor in the spotlight, but it is still available from operators and retail chains, usually a few hundred PLN cheaper. This is its only, but very strong argument. A year ago, Ultra 2 was in a similar situation, which we compared with its successor in the comparison of Ultra 3 and Ultra 2.

The Hermès version with a titanium bracelet is a separate price tier and purely a branding choice. Underneath, it’s the same watch.

Apple Watch Ultra 4 with the Alpine strap and Ocean strap. Photos: Apple.

Accessories for Apple Watch Ultra 4: everything from the older Ultra fits

Here is the best news of the entire comparison of Apple Watch Ultra 4 vs Ultra 3, and at the same time, something that no media outlet covering the premiere will tell you.

The case has identical dimensions of 49 × 44 × 12 mm across all four generations of the Ultra model. This means that bands, cases, glasses, and films purchased for Ultra 1, Ultra 2, or Ultra 3 will fit onto Ultra 4 without any modifications.

This is the opposite situation compared to the Series line. There, the Series 12 case changed dimensions compared to Series 11 (in the 46 mm version, it grew by a millimeter in width) and cases from the previous generation no longer fit. Nothing like that happened with the Ultra.

Element	Compatibility with Apple Watch Ultra 4
49 mm bands from Ultra 1 / 2 / 3	✅ fit without changes
44 / 45 / 46 mm bands from Apple Watch Series	✅ fit, same lug size
Cases for Ultra 1 / 2 / 3	✅ fit without changes
Glass and films for Ultra 49 mm	✅ fit, same cut
Bands from smaller Series cases (38–42 mm)	❌ different lug size
Cases, glass, and films from any Series	❌ different shape and size of the case

Bands from larger Apple Watch Series cases can be found in the 42–49 mm category — the same models support the Ultra.

Watch out for two traps. First, only the band attachment fits — cases and glass from the Series line have a different shape and will not fit the Ultra. Second, product cards will still say “Ultra 1 / 2 / 3” for a few more months, as they were created before the launch of the fourth generation. This describes the state at the time of the product’s market introduction, not a limitation.

Bands for Apple Watch Ultra 4

Bands for Apple Watch Ultra 3 and those for Ultra 4 are exactly the same product today, as the 49 mm lug has not changed since the first generation. Below are three proposals from different tiers.

UAG Civilian

UAG Civilian strap is the closest equivalent to the factory Trail band, only significantly sturdier. The soft silicone with an embossed pattern holds securely on a wet wrist, and the metal buckle does not unclip when snagged on a backpack.

The manufacturer lists models from Series 4 to Ultra 2 in the name because the strap has been available for several years. The 49 mm attachment has not changed, so it also fits the Ultra 3 and Ultra 4.

UNIQ Revix IV Premium

UNIQ Revix IV Premium solves a problem that most manufacturers do not consider: one strap, two colors. It is double-sided, so you can flip it depending on whether you are going for a run or to a meeting.

The magnetic clasp adjusts infinitely, without searching for the right hole. The size includes 44, 45, 46, and 49 mm, which fits both the Ultra and larger Series.

NOMAD Rocky Point Band

NOMAD Rocky Point Band is a proposal for someone who bought the Ultra 4 for the titanium and doesn’t want to ruin it with discount silicone. The FKM rubber is resistant to sweat, salt, and UV radiation, and the fittings are made of titanium in the same shade as the case.

FKM is the same material used for seals in diving equipment. It doesn’t stiffen in the cold and doesn’t yellow after the season.

If you’re looking for something more formal, the same manufacturer has a titanium bracelet NOMAD Stratos Band, which combines titanium links with FKM inserts.

We have gathered more proposals in the review of accessories for Apple Watch Ultra, and a separate compilation for running can be found in the text about sport bands for Apple Watch.

Cases and Glasses for Apple Watch Ultra 4

Sapphire glass is scratch-resistant, but not impact-resistant. It cracks from point contact with concrete or a door frame just like regular glass. The cost of screen replacement in the Apple Watch Ultra exceeds a thousand zlotys, so the bill for protection becomes straightforward.

Spigen Rugged Armor and tempered glass

Spigen Rugged Armor and Tempered Glass combines two things in one box: a flexible TPU case for the watch and glass for the screen. You don’t have to choose two products and check if they fit together.

The matte finish does not collect fingerprints, and the cutouts provide free access to the crown, side button, and orange action button. If you prefer a slimmer profile, the same manufacturer offers Spigen Liquid Air Pro.

UAG Scout

UAG Scout case is a choice for physical work and cycling. The protruding edge around the display absorbs impacts instead of the glass, and the reinforced corners protect the area where the titanium often hits the wall.

The manufacturer lists compatibility as “Ultra 1 / 2 / 3” because the product has been available since the launch of Ultra 3. The cut also fits Ultra 4.

Tech-Protect Glass Ring

Tech-Protect Glass Ring is an option for those who do not want to hide titanium under plastic. The metal frame in titanium color surrounds only the edge of the screen, while the rest of the case remains visible.

The set includes two pieces, so the first unsuccessful application does not end the matter. If you prefer a completely invisible solution, check out the Bizon Watch Film HydroFlex hydrogel film in a set of six or GrizzGlass hybrid glass.

Apple Watch Ultra 4 or Ultra 3: which one to choose?

The entire comparison boils down to five situations and five clear answers.

You have an Apple Watch Ultra 3 and are considering an upgrade. Stick with yours. The same screen, the same connectivity, the same satellite, and the same diving capabilities. Eight more hours of battery life are not worth the full price of a new watch, unless recovery training is your main reason for wearing it.

You have an Apple Watch Ultra 1 or Ultra 2. The jump is significant, but note: the biggest changes came with the Ultra 3, not the 4. Satellite, 5G, and a larger screen are thanks to the previous generation. If you find the Ultra 3 significantly cheaper, it will be a better purchase than paying extra for the latest model.

You are buying your first Apple Watch Ultra. Choose the Ultra 4. Since the entry price hasn’t changed, there’s no reason to reach for the predecessor at a price close to the new model.

You are looking for savings. Ultra 3 on sale from the operator. You get the same screen, the same case, satellite, 5G, and diving up to 40 meters. You only lose the new sensors, Readiness, and eight hours of battery life.

You are hesitating between the Ultra model and the regular Series. The Ultra is primarily about battery, satellite, and diving. If none of these three things are necessary for you, check out the cheaper Apple Watch SE 3. And if you are looking beyond the Apple ecosystem, compare it with Google Pixel Watch 5.

Summary

Apple Watch Ultra 4 vs Ultra 3 is a comparison of two very similar watches, where the entire difference lies in two areas: the battery and the sensors.

Five conclusions at the end:

1. The battery is the strongest argument: 50 hours instead of 42 and a quarter of charging giving 18 hours of operation instead of 12
2. The new sensor system measures heart rate every 5 seconds and unlocks the Readiness indicator, which Ultra 3 will not receive
3. The screen, case, satellite, and diving are identical, including 3,000 nits and EN13319 to 40 meters
4. The case has not grown, so bands, cases, and glasses from any previous Ultra fit without modifications
5. The entry price has not changed, so when purchasing for the first time, the newer model wins without discussion

If you stick with Ultra 3, invest in a good strap and glass instead of a new watch. If you switch to the fourth one, don’t buy accessories anew; the ones you have will fit without any problem.

FAQ: frequently asked questions

Do the bands from Apple Watch Ultra 3 fit Ultra 4?

Yes. The case has the same dimensions of 49 × 44 × 12 mm in both generations, and the strap attachment has not changed. A strap from Ultra 1, Ultra 2, or Ultra 3 will fit on Ultra 4 without modifications.

Does the case from Apple Watch Ultra 3 fit Ultra 4?

Yes. This is the main difference compared to the Series line, where the Series 12 case grew by a millimeter and the case no longer fit. In the Ultra line, the cut has been the same since the first generation, so the cases and glass are fully interchangeable.

How much does Apple Watch Ultra 4 cost in Poland?

Apple Watch Ultra 4 costs 3,799 PLN in the natural or black titanium version, always with GPS and cellular modem. This is exactly the same price at which Ultra 3 started a year earlier.

How long does the battery last in Apple Watch Ultra 4?

Up to 50 hours of normal usage and up to 84 hours in Low Power mode. During outdoor training with GPS and heart rate measurement, the watch lasts up to 18 hours, and in maximum extended training mode, up to 45 hours.

What’s new in Apple Watch Ultra 4?

There are three new things: battery (50 hours instead of 42), redesigned sensor system with heart rate measurement every 5 seconds and a Readiness indicator, and the Audio Intelligence package. The screen, case, satellite connectivity, and diving features remain unchanged compared to Ultra 3.

Is it worth buying Apple Watch Ultra 3 instead of Ultra 4?

It’s worth it if you find it clearly cheaper. The Ultra 3 has the same screen, the same case, satellite connectivity, 5G, and diving capabilities up to 40 meters. You lose new sensors, the Readiness indicator, and eight hours of battery life.

Is the Apple Watch Ultra 4 suitable for diving?

Yes, just like its predecessor. Both models are water-resistant up to 100 meters according to ISO 22810:2010 and have EN13319 certification for recreational diving up to 40 meters, with a depth measurement accuracy of ±1 m.

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Sources:

• Apple Newsroom, announcement of Apple Watch Ultra 4
• Specifications of Apple Watch Ultra 4
• Specifications of Apple Watch Ultra 3
• 9to5Mac, Apple Watch Ultra 4 vs Ultra 3