The Samsung Galaxy S25 Ultra and Xiaomi 15 Ultra are two of the most ambitious Android flagships of 2025, each aiming to set the bar for what a truly top-end, camera-focused smartphone should offer.
Both phones come with eye-watering price tags and a spec sheet to match, but their approaches to design, display, camera and software are distinctly different – and this might influence your buying decision, one way or the other.
We’ve thoroughly reviewed the Samsung Galaxy S25 Ultra and Xiaomi 15 Ultra, and here’s how the two fantastic flagships stack up in real-world use.
Pricing and availability
The Samsung Galaxy S25 Ultra is the cheaper of the two – though neither can exactly be described as affordable with price tags of over £1000.
The Samsung Galaxy S25 Ultra will set you back £1,249/$1,299 for the entry-level 256GB model, with up to 1TB available at additional cost.
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The Xiaomi 15 Ultra, on the other hand, costs £1,299 for a boosted 512GBGB model, also with up to 1TB available at extra cost. Both are available to buy now, following release earlier this year.
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Design
Samsung has given the Galaxy S25 Ultra a notable redesign this year, moving from the rounded edges and curved display of the S24 Ultra to a flat-edged, sharp-cornered look that brings it more in line with the rest of the S25 collection.
The result is a phone that feels more comfortable in the hand and offers better grip, though it arguably loses some of the unique ‘Ultra’ personality that set the previous models apart from the competition.
The Galaxy S25 Ultra is thinner, lighter and narrower than its predecessor at 8.2mm thick and 218g, and the new Gorilla Armor 2 glass, combined with IP68 resistance, promises even better durability.
The fan-favourite S Pen is still present, but it has lost Bluetooth connectivity, which means no more remote shutter or air gestures – although these are features we didn’t really miss much in daily use.
The Xiaomi 15 Ultra, on the other hand, sticks closely to the design language of its predecessor, the Xiaomi 14 Ultra. It’s still undoubtedly a chunky device, thanks in large part to the massive camera housing, but the curved edges help it sit more comfortably in the hand.
The new Silver Chrome finish, inspired by Leica cameras, adds a bold touch, and the glass rear is both fingerprint-resistant and visually striking with its shimmering finish.
At 226g and 9.3mm thick, it’s comfortably heavier and bulkier than the S25 Ultra, but the IP68 rating and Xiaomi Shield Glass 2.0 provide some peace of mind where durability is concerned.
Winner: Samsung Galaxy S25 Ultra
Screens
Samsung’s Galaxy S25 Ultra sports a slightly larger 6.9-inch Dynamic AMOLED 2X screen with a pixel-packed QHD+ resolution, LTPO-enabled 120Hz refresh rate and a peak brightness of 2600 nits.
The bezels are almost impossibly thin, and the anti-reflective coating is genuinely effective, making the screen a joy to use in all lighting conditions. Colours are vivid, and the display is bright enough for outdoor use without complaint.
There’s also the flat design of the screen, which means no accidental touches – the main issue with curved screens – and represents a massive win in the usability department.
Xiaomi counters this with its 6.7-inch curved AMOLED panel, also with WQHD+ resolution and a 120Hz LTPO-enabled refresh rate. The screen is even brighter, however, peaking at 3200nits, and boasts Xiaomi’s Wet Touch tech for use in the rain.
The colour tuning is also more natural than Samsung’s option out of the box, though you can tweak this to your liking in the Settings app.
While the curved edges look premium and make it feel way nicer when swiping from the side of the screen, we suffered from accidental touches – even with Xiaomi’s dead-zone software tech. The bezels are also thicker than Samsung’s alternative, making it look ever so slightly dated in comparison.
Winner: Samsung Galaxy S25 Ultra
Cameras
Both flagships are focused primarily on camera technology, so it’s here where the two phones mainly go head-to-head.
The Galaxy S25 Ultra sticks with a rather familiar camera setup comprised of a 200MP main sensor, 50MP 5x periscope, 10MP 3x telephoto and a new 50MP ultrawide.
In practice, the main camera continues to impress with its ability to capture sharp, detailed images in almost any lighting condition. Samsung’s processing leans towards punchy, vibrant colours – especially when it comes to greens and blues – which makes photos pop on social media, even if they’re not the most true-to-life you’ll find.
The 5x periscope zoom is a genuine improvement this year, delivering more detail and less of that ‘oil painting’ effect at higher zoom levels. We found the 30x zoom surprisingly usable, and even at 100x the results are better than most rivals, though still clearly AI-enhanced and rather blurry.
The new 50MP ultrawide is another welcome upgrade, especially in low-light, with less distortion at the edges and more consistent colour reproduction.
However, there’s still a noticeable quality dip between the 3x and 5x zoom ranges, and the 10MP 3x telephoto can’t quite keep up with the rest of the hardware in challenging conditions. For portraits, though, it remains the better focal length.
The Xiaomi 15 Ultra, on the other hand, is probably best described as a camera enthusiast’s perfect phone. The 1-inch 50MP main sensor is a genuine standout, capturing crisp, vibrant, and well-focused shots with almost effortless ease.
Low-light performance is exceptional, with the large sensor drawing out light in even the dimmest scenarios, sometimes to the point of looking brighter than reality. The Leica-branded shooting modes and filters also add a unique personality to photos, and we found ourselves using the Authentic mode to correct the occasional warm cast in indoor shots.
The 50MP 3x floating telephoto is one of the best for close-up and low-light zoom around, while the new 200MP 4.3x periscope lens is simply unmatched for detail at extreme zoom levels. Even at 30x or 35x, the Xiaomi holds onto more detail than the S25 Ultra, and the zoom range feels seamless – there’s no dead zone where quality drops off.
The only real letdown is the 50MP fixed-focus ultrawide, which feels like a missed opportunity given the rest of the hardware. We also noticed some inconsistency in colour science between lenses, particularly with shades of blue. Still, the overall experience is so strong that these are easy to overlook.
Winner: Xiaomi 15 Ultra
Performance
Both phones are powered by Qualcomm’s top-end Snapdragon 8 Elite chipset, which boasts some of the best processing power in a mobile chipset right now – though the S25 Ultra sports a custom ‘For Galaxy’ edition of the chipset with slightly higher clock speeds.
Unsurprisingly, both are lightning fast in day-to-day use, handling everything from games to multitasking with ease. The S25 Ultra does edge ahead in benchmarks, especially in multi-core CPU and GPU tests, but the difference is negligible in real-world use.
Both phones can get warm under heavy load, but neither suffers from significant throttling as a result, meaning both can double as capable gaming phones – though Xiaomi’s curved screen might not help in this regard.
Storage and RAM options are generous on both flagships too, with up to 1TB of storage and 16GB of RAM available on both – though the Xiaomi 15 Ultra starts at 512GB compared to Samsung’s 256GB.
Winner: Samsung Galaxy S25 Ultra
Software
Samsung’s One UI 7, based on Android 15, brings a new look and a few new Galaxy AI features, but many of these feel half-baked or limited in scope. The Now Brief and multi-app AI actions are promising, but not as useful as you might think in daily life, and most of the new features are also being introduced to other Samsung devices. There’s nothing really ‘exclusive’ here.
The real win, however, is Samsung’s long-term software promise, committing to seven years of OS upgrades and security patches that’ll take it through to One UI 14 based on Android 22.
Xiaomi’s HyperOS 2, also based on Android 15, is a big improvement over the older MIUI interface, offering a cleaner, more intuitive experience with much better Google integration. There’s still some bloatware and Xiaomi-branded apps, but it’s less intrusive than before.
Xiaomi’s AI focus is mainly on photo editing, with tools available for object removal, enhancement and expansion, though you’ll also find similar features to Samsung’s Galaxy AI in text rewriting, translation, and transcription functionality.
Xiaomi doesn’t quite offer the same level of software support, however, offering just four OS upgrades and six years of security patches.
Winner: Samsung Galaxy S25 Ultra
Battery life
The Galaxy S25 Ultra sticks with the same 5000mAh battery as the S24 Ultra, and once again delivers reliable all-day performance – though it does fall behind 2025 rivals with larger cells.
In testing, we typically finished the day with 20-30% left after moderate use, with around three or four hours of screen time. Charging is faster this year despite offering the same advertised 45W, offering 70% in 30 minutes and a full charge in just over an hour – but you’ll need to supply your own charger.
Wireless charging is capped at 15W, though it was one of the first phones to ship with support for the updated Qi 2.1 wireless standard.
The Xiaomi 15 Ultra packs a larger 5410mAh battery, and we found it easily lasted all day, even with heavy use of 5+ hours. Charging is rapid with 90W and 80W wireless support – though you’ll need HyperCharge-branded chargers to take advantage of those speeds.
Using a regular USB-C PD charger, we saw 52% in 30 minutes and a full charge in 90 minutes, so it’s best to invest in a branded charger if possible.
Regardless, Xiaomi’s battery life is a step ahead of Samsung’s in use, especially for power users.
Winner: Xiaomi 15 Ultra
Final thoughts
Both the Samsung Galaxy S25 Ultra and Xiaomi 15 Ultra are both some of the best camera phones around in 2025, they cater to slightly different audiences.
The S25 Ultra is the safer, more refined choice, with a gorgeous flat screen, versatile camera system and impressive long-term software support. It’s a true flagship all-rounder, though it doesn’t push mobile tech to its absolute limits as some might hope.
The Xiaomi 15 Ultra, on the other hand, is the phone for photography enthusiasts. Its camera system is simply the best we’ve used to date, and the display and battery life are top-tier. It’s bulkier and the software support isn’t as long, but if you want the ultimate camera phone, this is it.
Ultimately, you can’t go wrong with either, but your priorities – camera, design, software or battery life – will dictate which is the better fit for you.
