Samsung Galaxy Watch Ultra 2 vs Apple Watch Ultra 4: Which to Buy?

Your phone has already made this choice for you.

The Galaxy Watch Ultra 2 works only with an Android phone, and the Apple Watch Ultra 4 works only with an iPhone. So this is not really a piece about which watch to buy, it’s about which is better.

The short answer: both are serious endurance watches with two to three days of battery and enough GPS for an Ironman, Ultra or Weekend of riding. Apple wins on safety with satellite off-grid connectivity. Samsung wins on built-in navigation and trail tools, on body composition, and on price. And there is a catch inside Android: some of Samsung’s health features only work if your phone is a Samsung too.

I’m testing the Apple Watch Ultra 4 at the time of writing. but both brands’ figures are based on their claims. The testing methodology explains how I test.

The full figures are on the Galaxy Watch Ultra 2 and Apple Watch Ultra 4 specification pages. If you are choosing within one brand instead, see Galaxy Watch 9 vs Galaxy Watch Ultra 2 or Apple Watch Ultra 4 vs Series 12.

Which is better for you?

If you want	Choose	Because
A watch for your iPhone	Apple Watch Ultra 4	Samsung doesn’t work with an iPhone.
A watch for your Android phone	Galaxy Watch Ultra 2	Apple doesn’t work with Android. Some Samsung Health features need a Samsung phone.
Events longer than 20 hours	Apple Watch Ultra 4	Apple claims up to 45 hours in its longest mode. Samsung’s longest claim is 20 hours.
Help when there is no phone signal	Apple Watch Ultra 4	It can call for help and send messages by satellite. The Samsung cannot.
The lower price	Galaxy Watch Ultra 2	£649 or $699.99 against £749 or $799.
Following a route without buying an app	Galaxy Watch Ultra 2	Route guidance and a trail run mode are built in. The Apple Watch needs an app such as WorkOutDoors.
A daily readiness score and training load	Either	Apple has Readiness, Samsung has Energy Score and Daily Cardio Load. Neither charges a subscription.
A dive computer	Apple Watch Ultra 4	With the Oceanic+ app, it is one. Samsung’s is a depth gauge for now.
Body composition on the wrist	Galaxy Watch Ultra 2	Samsung measures it. Apple does not.

Which phones they work with

Samsung says the Galaxy Watch Ultra 2 needs a phone running Android 13 or later, a Samsung account and the Samsung Health app.

There is a second fence inside Android. In a newsroom article from 31 August 2026, Samsung says that the ECG, irregular heart rhythm warnings and sleep apnoea detection work “when used alongside a compatible Samsung Galaxy phone”. It lists Running Coach and the new Gemini features the same way. Blood pressure runs through the same Samsung app, which Samsung’s UK support pages describe as Samsung-only, and it depends on your country too. If your phone is a Pixel or any other Android, you get a reduced watch. Complicated, right?

Apple’s rule is simpler. Apple’s specification page asks for an iPhone 11 or later, including the second-generation iPhone SE onwards, running iOS 27. Every feature works on every qualifying iPhone.

Battery life and charging

Maker’s claim	Galaxy Watch Ultra 2	Apple Watch Ultra 4
Everyday use	Up to 60 hours, or 80 with the always-on screen off	Up to 50 hours
Low power mode	Not available for this watch	Up to 84 hours
A run or ride with GPS	Up to 20 hours	Up to 18 hours
Longer GPS modes	Up to 16 hours while following a route	Up to 25 hours, or 45 with some features turned off
Quick top-up	About 40 per cent in half an hour	About 80 per cent in 45 minutes

The two companies don’t measure “everyday use” the same way, so 60 hours against 50 isn’t a fair fight. In practice, both amount to the same thing: two or three days between charges, and enough GPS for most adventures and almost any event.

The difference is beyond 20 hours. Apple’s longest mode claims 45 hours, and I set out what it costs you in four changes in Series 12 and Ultra 4: the GPS drops to its less accurate setting, and you lose splits, alerts and custom workouts. Samsung has published no equivalent figure for the Ultra 2.

Apple also charges faster, at roughly twice Samsung’s rate. Samsung’s figure assumes the charger is in the box and that you use a charger of at least 10 watts. I go through the chargers in Galaxy Watch vs Apple Watch charging speed.

Apple appears to be a generation ahead.

GPS

Both watches use the more accurate dual-frequency GPS. Apple dropped GLONASS this year, which I don’t expect anyone to notice. Samsung doesn’t say which satellite systems it uses, but it’s likely the same as Apple.

My own evidence covers Apple only. In an open-water swim at Shepperton Lake, the Ultra 4’s track was good but slightly more ragged than the Garmin Fenix 9 Pro’s on the same swim, and I judged the Garmin’s more believable. Elsewhere, Apple shows the same behaviours as previous years, like rounding corners, but it just doesn’t feel as accurate to me, scoring a very average 79% (same as the Fenix 9 Pro but well behind the Forerunner 970). I have comparable data for the Samsung.

Heart rate and health

The Ultra 4 has Apple’s new heart sensor, which Apple says reads your heart rate every five seconds through the day and your heart rate variability as often as every five minutes. In the Heart Analyser comparison, written by the app’s developer and based on one person’s data, it saved a heart rate reading about every 30 seconds while awake and about 100 HRV readings a night. The Ultra 4 also has an ECG, blood oxygen, skin temperature and a Readiness score out of 10.

The Samsung has a heart rate sensor, an ECG, a temperature sensor and body composition, which Apple does not offer. Its software adds Energy Score, Heart Health Score and a blood pressure reading that you have to recalibrate against a proper cuff every four weeks. I have not tested the accuracy of any of them.

Apple claims its new optical heart rate sensor is the most accurate ever. All my testing to date supports that. Well, unless you count recording only one value every 5 seconds at 20% accuracy, then I guess it’s the worst ever! You decide.

Diving and toughness

Both are rated to 100m and certified for recreational diving to 40m. The difference is what the watch does down there. Samsung’s Depth app shows your depth, water temperature, and how long you have been down, but not how long you can safely stay, so for now it is a depth gauge. With the Oceanic+ app, the Ultra 4 is a proper dive computer.

Both are titanium with sapphire glass. The Samsung has two extra toughness ratings: high-pressure water jets and military-style abuse. The Samsung is slightly smaller, thinner and lighter, and its screen is brighter in full sun.

Again, Apple seems to be a year or two ahead here.

Safety when you are on your own

The Ultra 4 can call for help, send and receive messages and share your location by satellite when there is no phone signal, free for two years. The Samsung has no satellite connection, so its emergency call depends on a mobile network or your phone. If you train alone beyond phone coverage, this is the biggest difference between the two watches, and no software update will close it. Both have a loud siren, fall detection, and a built-in mobile connection.

Apple is at least two years ahead here.

Sport features and apps

Samsung builds more of the sport features into the watch. The Ultra 2 has a trail run mode that shows you the climb ahead, turn-by-turn directions along a route you load, and a direct connection to cycling power meters, speed sensors, and cadence sensors, with FTP worked out on the watch.

Apple’s Workout app handles triathlon transitions automatically but cannot load a route and cannot talk to ANT+ sensors. As I described in Garmin Fenix 9 vs Apple Watch Ultra 4, apps fill the gaps: WorkOutDoors adds offline maps and routes.

Strava works on both, and Samsung uploads automatically. Stryd has apps for both too.

Price

The Galaxy Watch Ultra 2 went on sale on 7 August 2026 at £649 or $699.99. The Apple Watch Ultra 4 is £749 or $799. The £100 difference is small compared with the cost of changing phones.

Which one should you buy?

• Choose the Apple Watch Ultra 4 if you own an iPhone. you know what to do! It is the only one that will work, and it brings satellite safety and longer GPS modes.
• Choose the Galaxy Watch Ultra 2 if you own a Samsung phone. You get every feature, built-in routes and trail tools, and you pay £100 less. If you own an older Samsung watch, the Galaxy Watch upgrade guide and Ultra 2 vs the original Ultra cover you.
• Think twice about the Galaxy Watch Ultra 2 if your Android phone isn’t a Samsung and you want ECG, heart rhythm warnings, or sleep apnoea detection, because Samsung ties those to its own phones. Pixel watches are excellent, but none match the Galaxy Watch Ultra’s rugged form factor.
• If you are choosing a phone and a watch together, choose the phone first. iPhone and Siri definitely lag behind Android and Gemini. Satellite safety, very long events and the Apple ecosystem favour Apple. Built-in navigation and the lower price favour Samsung.

Quick answers

Does Galaxy Watch Ultra 2 work with an iPhone?
No. Samsung says it needs a phone running Android 13 or later.

Does Apple Watch Ultra 4 work with Android phones?
No. Apple requires an iPhone 11 or later, or a second-generation iPhone SE or later, running iOS 27.

Do I need a Samsung phone for ECG on Galaxy Watch Ultra 2?
Yes. Samsung says the ECG, irregular heart rhythm warnings and sleep apnoea detection need a compatible Samsung Galaxy phone. Blood pressure uses the same Samsung app and depends on your country.

Which has better battery life, Galaxy Watch Ultra 2 or Apple Watch Ultra 4?
They are close in everyday use: Samsung claims up to 60 hours and Apple up to 50, measured in different ways. For a GPS workout, Samsung claims up to 20 hours, and Apple up to 18, but Apple’s longer modes reach a claimed 25 and 45 hours.

Which charges faster, Galaxy Watch Ultra 2 or Apple Watch Ultra 4?
The Apple. It claims about 8% in 45 minutes. Samsung claims about 40 per cent in half an hour with its own charger and a phone charger of at least 10 watts.

Does Galaxy Watch Ultra 2 have satellite SOS like Apple Watch Ultra 4?
No. The Galaxy Watch Ultra 2 has no satellite connection. The Apple Watch Ultra 4 can call for help, send messages and share its location by satellite, free for two years.

Can you dive with Galaxy Watch Ultra 2 and Apple Watch Ultra 4?
Yes, both are certified to 40m. Samsung’s Depth app shows depth, water temperature and dive time but does not yet track safe time at depth. The Apple Watch Ultra 4 works as a full recreational dive computer with the Oceanic+ app.

Last Updated on 2 October 2026 by tfk the5krunner