Xiaomi 15 Ultra vs Galaxy S25 Ultra: The most extreme Ultra flagships
Intro
The Galaxy S25 Ultra has been out for a couple of weeks now, and it's first serious competitor has already also unmasked itself––Xiaomi's 15 Ultra top flagship for 2025.
Coming in hot with the latest Qualcomm hardware, a bright and lovely display, a trove of AI features, and excellent camera performance, this one is a device that fares best when swinging at the top of the food chain, right next to the Galaxy S25 Ultra.
The same is mostly true for the Galaxy S25 Ultra itself, but some hardware components and features have remained mostly stagnant in comparison with the previous Galaxy S24 Ultra generation. The S Pen-clad Samsung flagship is still among the best, but the Xiaomi 15 Ultra is definitely on the same level.
So, which one should you pick?
Xiaomi 15 Ultra vs Galaxy S25 Ultra similarities and differences:
| Xiaomi 15 Ultra | Galaxy S25 Ultra |
|---|---|
| Slightly shorter and narrower, but thicker and heavier | Taller and wider, but thinner and lighter |
| Faux leather and reinforced plastic back, aluminum frame | Titanium frame with Gorrila Glass Armor 2 backplate |
| Quad-curved 6.7" display with Xiaomi Shield Glass 2.0 | Flat 6.9" Dynamic AMOLED 2X screen with Gorilla Glass Armor 2 with anti-reflective coating |
| Lower-res 50MP main camera with massive 1-inch Sony LYT-900 sensor | Higher-res 200MP main camera with large 1/1.3-inch ISOCELL sensor |
| Higher-res 200MP 4.3X periscope camera with large 2.24µm pixels | Lower-res 50MP 5X periscope camera with F3.4 aperture |
| Slightly slower 50MP F2.2 ultrawide camera | Slightly faster 50MP F1.9 ultrawide camera |
| Larger 5,410mAh battery | A standard 5,000mAh battery |
| Much faster 90W wired and 80W wireless charging | Slower 45W wired and 15W wireless charging |
| Black, White, Silver Chrome colors | Black, Gray, Silver Blue, and White Silver (Pinkgold, Jetblack, and Jadegreen) |
Table of Contents:
Design and Display Quality
Large versus… larger
From the get-go, these are two pretty different phones.
The Xiaomi 15 Ultra employs a slightly less premium design, with an aluminum frame and dual-tone backplate, combining faux leather with composite plastic. We have a flat frame, but the display is quad-curved on all sides, which makes gesture navigation oh-so-comfortable and rewarding.
However, although not as "nice" as the titanium-glass sandwich that is the Galaxy S25 Ultra, the Xiaomi 15 Ultra does feel great in the hand and offers a reassuring grip, which normally isn't the case with the slippery matte glass on the Samsung flagship. It's mostly similar to last year's Xiaomi 14 Ultra in aesthetics, but has grown and elevated all the key design areas further.
At the same time, the Galaxy S25 Ultra has scored a redesign in comparison with the Galaxy S24 Ultra, now featuring slightly rounded corners similarly to the rest of the Galaxy S25 series.
The Xiaomi 15 Ultra has a massive camera island, which makes the phone a bit top-heavy, but that's a necessary shortcoming given the camera prowess hidden beneath.
The display is completely flat, and at the bottom, we find a staple of the Galaxy S Ultra range––the S Pen, still a rather unique hardware feature that hasn't been employed by another manufacturer and has a steady fan base.
Neither the Xiaomi 15 Ultra nor the Galaxy S25 Ultra boast any custom buttons aside from the standard ones, so it's business as usual here.
Size-wise, the Xiaomi 15 Ultra is slightly shorter and narrower, making it a bit easier to use with a single hand, but it's also thicker and slightly heavier. At the same time, the Galaxy S25 Ultra is taller and slightly wider, but it's also thinner and lighter, so it's a different type of tradeoff.
Colors-wise, the Xiaomi 15 Ultra is a bit more laid back, with three distinct color versions. There's the standard black and white, but the real star of the show is the dual-tone Silver Chrome phone (which we had in for review), which aims to replicate the look of an old Leica camera and even features a small viewfinder-like doodad at the rear. It absolutely stands out.
Both devices feature the now-standard IP68 water- and dust-resistance. There's no IP69 support here, which offers even greater protection against water jets. The Xiaomi 15 Ultra also has an IR blaster hidden in the camera volcano.
With the Xiaomi 15 Ultra, we get a 6.73-inch QHD+ OLED display, slightly smaller than the 6.9-inch QHD+ screen on the Galaxy S25 Ultra. It's also slightly curved on all sides, so you technically get slightly less actually usable area than what you get on the Galaxy flagship. Both panels are super-smooth LTPO ones, dynamically switching between 1 and 120Hz depending on the on-screen content.
In terms of colors, both are very accurate out of the box and look stunning. The Xiaomi definitely offers more screen personalization, though, with different modes, settings, and so much more. You can choose between Vivid, Natural, sRGB, P3, as well as tweak all settings yourself. The default mode, Original Color PRO, is probably the best one, though.
The Galaxy S25 Ultra, on the other hand, only lets you pick between the Natural and Vivid modes, with the only user-customizable options being the white balance and saturation in the Vivid mode. Not bad, but not great either.
One area in which the Galaxy S25 Ultra gets beaten completely is the peak brightness. At 20% APL, which measures the maximum brightness when a fifth of the display shows a completely white area, the Xiaomi 15 Ultra achieves 3,210 nits of max brightness, nearly a thousand nits more than the 2,373 that we measured on the Galaxy S25 Ultra in the same test.
However, in real-life conditions, legibility under bright lighting conditions is mostly even thanks to the Galaxy's second-gen anti-reflective coating, which eliminates most reflections.
Biometrics-wise, both have fingerprint scanners embedded into the display, and they work fast and reliably. Face Unlock, certainly less secure, is also available on both.
Performance and Software
Snapdragon power
Both phones come with the latest and greatest Qualcomm Snapdragon 8 Elite chip, which is currently one of the few 3nm chips available to Android manufacturers. Technically, the Galaxy S25 Ultra features a Snapdragon 8 Elite for Galaxy, slightly overclocked and with some extra custom features embedded into it, like a new ProVisual Engine for the camera.
In terms of overall performance, both phones are extremely fast, so fast that it's impossible to notice a difference in favor of either one. In synthetic benchmarks, however, the Galaxy S25 Ultra reigns supreme in the CPU-heavy Geekbench tests, both the single- and multi-core ones, which is logical to expect due to the overclocked specs of the Samsung flagship.
At the same time, the Xiaomi 15 Ultra beats the Galaxy S25 Ultra in the graphics stress test, reaching higher results in both the high test (which demonstrates the initial burst of performance) and the low test, which showcases how the phone performs when throttled.
Both phones come with lots of RAM and storage, but it's the Xiaomi 15 Ultra that is better-spec'd here. It features 16GB of RAM and comes with either 512GB or 1TB of storage. There's also a convenient memory extension feature, allowing you to use up to 16GB of your storage as RAM.
The Galaxy S25 Ultra comes with 12GB of RAM, as well as either 256GB, 512GB, or 1TB of storage. It also has a memory extension feature, dubbed RAM Plus, which lets you expand the memory, but only up to 8GB.
Software and AI
In terms of software, both phones come with Android 15 out of the box.
On the Galaxy S25 Ultra, we get seven years of software updates and security patches.
The Samsung phone comes with Galaxy AI on board, which features a ton of features sprinkled throughout the interface. You can process data either on the phone or in the cloud. We get the usual Call Assist real-time translations, Writing Assist tools for composing and organizing text, Interpreter (real-life conversation translation), Note Assist for auto-formatting notes, Transcript Assist, and Browsing Assist.
On the visual front, we have Photo Assist that lets you edit your images and remove unwanted objects from your photos, as well as Drawing Assist, which lets you reimagine your S Pen sketches as AI drawings. A cool new feature is Audio Eraser, which identifies up to six categories of sounds in your videos and allows you to either boost or isolate them.
Meanwhile, the Xiaomi 15 Ultra comes with slightly revamped interface aesthetics and new features, delivered by the company's so-called HyperCore platform. One of my favorite new features are the customizable lock screens, which feature a ton of personalization options. Xiaomi's HyperConnect lets you seamlessly connect with other Xiaomi devices in an ecosystem and hand-off apps, activities, and so on.
In terms of AI, the Xiaomi 15 Ultra comes with the usual suspects. There's an AI writing tool assistant that can copy write, polish your text, and summarize it. In the Gallery app, you get a whole trove of AI features that are all pretty self-explanatory: AI Enhance, AI Expand, AI Erase, Remove Reflections, and Sky, which swaps the sky in your photos for a custom one. In my experience, all of these features are quite intuitive and work pretty well, certainly not worse than the ones on the Galaxy S25 Ultra.
Camera
Quad-camera champions!
And there we have it, the one area in which the Xiaomi 15 Ultra and Galaxy S25 Ultra can finally trade some heavy blows! Both devices come with very capable camera sets, and spoiler alert, these two are the best cameras we've tested so far.
The Xiaomi Ultra is all about that Leica-powered camera, and it would be safe to say it's basically a camera that lets you check your Facebook feed on the side. Its main camera is equipped with a massive 1-inch Sony LYT-900 sensor, which delivers exceptional results.
Another highlight is the massive 200MP periscope that offers 4.3X optical zoom, but thanks to the high resolution, zooming by artificially cropping in delivers exceptional results even at very high zoom ranges.
There's also a 50MP 3X telephoto and another 50MP ultrawide, rounding up the exceptional camera hardware inside the camera volcano at the back.
With the Galaxy S25 Ultra, we get a 200MP main camera with a fairly large sensor, aided by a 50MP periscope lens with 5X optical zoom, as well as a 10MP 3X telephoto and a 50MP ultrawide. Aside from the ultrawide, this setup is pretty similar to last year's Galaxy S24 Ultra, and that's alright––both phones are exceptional in terms of camera performance.
Boasting a new ProVisual engine, the Galaxy S25 Ultra ushers in a new level of realism for photos and videos, delivering significantly better results than its predecessor with no oversharpening or overprocessing.
And the verdict is in! According to the PhoneArena camera score test, it's the Xiaomi 15 Ultra that takes the lead, but the Galaxy S25 Ultra is not far behind. One thing is for certain: both are exceptional camera phones!
Now let's take a look at a couple of comparative camera samples.
Main Camera
In broad daylight, both are exceptional, delivering superb and very natural detail with no sign of oversharpening or overprocessing, excellent exposure, and beautiful colors that are true-to-life but still pleasingly vibrant.
In lower light, it's the Xiaomi 15 Ultra that looks more natural, although at the expense of slightly less detail. The Galaxy is a bit more dramatic and contrast-y, which helps with the detail but lacks the natural looks of its rival.
Zoom Quality
Zooming it to 3X, which is native to both phones, reveals that the Xiaomi is slightly more detailed and delivers a better overall exposure, with colors that are truer to real-life.
At 5X for the Galaxy and 4.3X for the Xiaomi 15 Ultra, sharpness is once again a bigger strength for the Xiaomi phone.
At 10X, the larger sensor of Xiaomi 15 Ultra's periscope camera gives us slightly better results once again, but the Galaxy S25 Ultra is close behind.
Ultrawide Camera
Both devices give us equally wide ultrawides, which correspond to 14mm focal length and fit a lot in the scene. Aside from the slightly higher exposure, the two phones perform very similarly.
Selfies
Both front cameras are very detailed. The main difference here are the colors, which are truer to real-life with the Samsung flagship phone, whereas the Xiaomi delivers a slightly yellow-ish cast over my face.
Video
In terms of video, both are chockful with options. The Xiaomi 15 Ultra and the Galaxy S25 Ultra can both take 8K videos at 30 or 24fps, as well as 4K videos at 60 or 30fps. The Xiaomi 15 Ultra can also capture 4K@120fps videos in the standard video-recording mode with either the main camera or the periscope one, while the Galaxy S25 Ultra can only do that in its Pro Video mode, and only with the ultrawide or the main cameras.
Audio Quality
Despite both phones have stereo speakers, it's the Galaxy S25 Ultra that sounds decidedly better. It delivers louder sounds without much distortion at high volume, with deep bass and expansive soundstage. More importantly, the audio sounds more or less equal from the bottom loudspeaker and the top speaker.
That's not very true of the Xiaomi 15 Ultra, which has dual stereo speakers, but the top one is too weak, so the sound is one-sided. As a result, the sound stage isn't very wide, and listening to audio on this phone isn't very rewarding.
Haptics are arguably better on the Galaxy S25 Ultra. The Xiaomi 15 Ultra has a very decent vibrator, but it is definitely on the weaker side, despite being crisp and accurate.
Battery Life and Charging
Great battery life
The Xiaomi 15 Ultra comes with a fairly large for its size 5,410mAh battery, which features around 10% silicon-carbide content that helps with the energy density. In a world where most phones hailing from China come with 6,000mAh batteries, the Xiaomi 15 Ultra is certainly on the leaner end, but at least it has a larger battery than the Galaxy S25 Ultra, which for yet another year in a row comes with a fairly small for its size 5,000mAh battery.
Which one performs better in our tests?
Well, it's the Galaxy S25 Ultra that pulls ahead with a total average battery life of eight hours, half an hour more than the Xiaomi 15 Ultra.
Broken down by category, those results reveal that the Xiaomi 15 Ultra does very well in our dedicated video playback test, where it lasts a little over 10 hours, whereas the Galaxy S25 Ultra almost achieves 9 hours.
In our web browsing test, which aims to emulate a standard browsing experience with the screens set at 200 nits, the Xiaomi 15 Ultra achieves 16 hours and a half, but the Galaxy S25 Ultra pulls ahead with nearly 21 hours. Finally, in the 3D gaming test, which is conducted at 60fps, the score is once again in favor of the Galaxy S25 Ultra, which reaches 14 hours and 21 minutes, nearly an hour extra in comparison with the Xiaomi 15 Ultra.
PhoneArena Battery and Charging Test Results:
Charging-wise, however, it's a triumph for the Xiaomi phone. Equipped with 90W wired and 80W wireless charging, on paper it beats the Galaxy 25 Ultra, which still relies on 45W wired and 15W wireless charging. However, this translates to just a 6-minute difference in the wired charging speeds between the two.
Specs Comparison
Here's how the Xiaomi 15 Ultra vs Galaxy S25 Ultra specs compare:
| Xiaomi 15 Ultra | Galaxy S25 Ultra |
|---|---|
| Size, weight 161.3 x 75.3 x 9.35 mm, 226 gr (Black, White), 229 gr (Silver Chrome) | Size, weight 162.8 x 77.6 x 8.2 mm, 218 gr |
| Screen 6.73" AMOLED 3200 x 1440 pixels 1-120Hz LTPO 3,200-nit peak brightness HDR10+, Dolby Vision | Screen 6.9" AMOLED 3120 x 1440 pixels 1-120Hz LTPO 2,600-nit brightness HDR10+, Dolby Vision |
| Processor Snapdragon 8 Elite 3nm | Processor Snapdragon 8 Elite 3nm |
| Versions: 16GB/512GB 16GB/1TB LPDDR5X | Versions: 12GB/256GB 12GB/512GB 12GB/1TB LPDDR5X |
| Cameras: 50MP F1.63 LYT-900 1" wide 50MP F1.8 IMX858 3X telephoto 200MP F2.6 HP9 4.3X periscope 50MP F2.2 JN5 ultrawide 32MP F2.0 OV32B front | Cameras: 200MP F1.7 ISOCELL HP2 1/1.3" wide 10MP F2.4 IMX754 3X telephoto 50MP F3.4 Sony IMX854 5X periscope 50MP F1.9 S5KJN3 ultrawide 12MP F2.2 front |
| Battery: 5410mAh 90W wired charging 80W wireless charging | Battery: 5000mAh 45W wired 15W wireless |
| Charging: USB-C 27W wired MagSafe | Charging: USB-C 23W wired MagSafe |
Summary
The Xiaomi 15 Ultra is the Galaxy S25 Ultra's first major rival to match its might in most aspects.
Both are among the absolute best Android phones right now, and are pretty much equals when you factor in most areas. Sure, one has slightly better battery life, the other boasts a much brighter screen, performance benchmarks are traded between the two, and the camera performance is mostly equalized.
Ultimately, the Xiaomi's more limited availability will be the deciding factor for its success. You will have to go through some hurdles to get it in the USA, it won't be as easy as entering a T-Mobile store, for example.
Overall, the Xiaomi 15 Ultra is aimed at those who value the camera experience, which is the highlight here. Everything from the design to the available features is geared towards providing you with a superb, tinker-friendly experience. At the same time, the Galaxy S25 Ultra aims to be the jack of all trades, and as usual, Samsung has somehow made its top phone the master of most of those.
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