Samsung Galaxy S25 Ultra VS Xiaomi 15 Ultra

Both the Samsung Galaxy S25 Ultra and the Xiaomi 15 Ultra share an IP68 waterproof rating and neither adopts a rugged or foldable form factor, so they start from the same baseline in terms of protection and build category. In daily use, IP68 means both can handle submersion in fresh water up to the standard depth without issue — a genuine parity point that requires no further distinction.

Where the two diverge meaningfully is in their physical footprint. The S25 Ultra is notably slimmer at 8.2 mm versus the Xiaomi 15 Ultra's 9.4 mm — a 1.2 mm difference that is perceptible in-hand and in a pocket. It is also lighter at 218 g compared to 229 g, an 11-gram gap that becomes noticeable during extended one-handed use or long reading sessions. The overall displaced volume reflects this clearly: the S25 Ultra occupies roughly 103.6 cm³ versus the Xiaomi's 114.2 cm³, making it a meaningfully more compact device despite being slightly wider (77.6 mm vs 75.3 mm) and fractionally taller.

On design ergonomics, the Samsung Galaxy S25 Ultra holds a clear edge — it is the thinner, lighter, and less voluminous device of the two. The Xiaomi 15 Ultra's extra bulk likely accommodates internal hardware choices (such as a larger battery or camera system), but purely from a form-factor standpoint, the S25 Ultra will feel more refined and easier to manage over the course of a full day.

The two screens are closely matched in technology — both OLED/AMOLED panels with 1440p resolution, 120Hz refresh rates, HDR10/HDR10+ support, and Always-On Display. For most users glancing at the spec sheet, these similarities might suggest near-identical viewing experiences. But the details tell a more nuanced story.

The Xiaomi 15 Ultra's display pulls ahead in several measurable ways. Its 522 ppi pixel density edges out the S25 Ultra's 498 ppi — a difference attributable to packing a similar resolution into a smaller 6.73″ panel versus Samsung's 6.9″ screen. More striking is the contrast ratio gap: 8,000,000:1 on the Xiaomi versus 3,000,000:1 on the S25 Ultra, which translates to deeper blacks and more vivid shadow detail in dark content. The Xiaomi also reaches a higher typical brightness of 3,200 nits compared to 2,600 nits, offering a tangible advantage in direct sunlight readability. Its 300Hz touch sampling rate (versus 240Hz) further sharpens responsiveness for fast-paced gaming and precise stylus or finger input. Additionally, the Xiaomi's exclusive support for Dolby Vision means compatible streaming content — from Netflix to Apple TV+ — renders with its intended color grading, a perk the S25 Ultra cannot match.

The S25 Ultra's counterargument is its branded damage-resistant glass, which provides a real-world durability assurance the Xiaomi 15 Ultra lacks. A larger screen also suits media consumption and multitasking for users who prioritize canvas size. Still, on display quality metrics alone — brightness, contrast, pixel density, touch responsiveness, and HDR format breadth — the Xiaomi 15 Ultra holds a clear overall edge.

Both the Samsung Galaxy S25 Ultra and the Xiaomi 15 Ultra come with 1024GB of internal storage, ensuring ample space for apps, media, and files. In terms of RAM, the Samsung Galaxy S25 Ultra offers 12GB, while the Xiaomi 15 Ultra has a larger 16GB of RAM. The Galaxy S25 Ultra has an AnTuTu benchmark score of 2207809, while the Xiaomi 15 Ultra surpasses it with a score of 2746580. The CPU speeds for both devices are very similar, with the Galaxy S25 Ultra having a CPU configuration of 2 x 4.47 GHz & 6 x 3.53 GHz, and the Xiaomi 15 Ultra featuring 2 x 4.32 GHz & 6 x 3.53 GHz. Both devices feature Qualcomm Snapdragon 8 Elite chipsets and Adreno 830 GPUs.

The Geekbench 6 results show the Galaxy S25 Ultra scoring 9846 in multi-core and 3057 in single-core, while the Xiaomi 15 Ultra scores slightly higher with 10059 in multi-core and 3234 in single-core. For 3DMark Steel Nomad benchmarking, the Galaxy S25 Ultra achieves a score of 2318, while the Xiaomi 15 Ultra has a lower score of 2152. Both phones have the same GPU clock speed of 1100 MHz and support LTE. RAM speed for both devices is the same at 5300 MHz, and both feature a 3 nm semiconductor size.

Other shared features include support for 64-bit processing, DirectX 12, integrated graphics, OpenGL and OpenGL ES versions 3.2, and big.LITTLE technology. The Galaxy S25 Ultra and the Xiaomi 15 Ultra both support multithreading and use HMP (Heterogeneous Multi-Processing). The memory bandwidth is the same for both devices at 85.1 GB/s, and they both have the same number of memory channels (2), L1 cache (192 KB), L2 cache (12 MB), L3 cache (8 MB), and support for ECC memory. Both also support a maximum memory amount of 24GB. Neither device has any notable differences in GPU turbo, Thermal Design Power (TDP), or supported displays, which remain at 1100 MHz, 8.2W, and 2 displays respectively.

The Samsung Galaxy S25 Ultra and Xiaomi 15 Ultra both feature impressive multi-lens camera setups. The Galaxy S25 Ultra boasts a 200 MP main camera, along with 50 MP, 50 MP, and 10 MP lenses, while the Xiaomi 15 Ultra has a slightly different configuration with a 200 MP main camera, 50 MP, 50 MP, and 50 MP lenses. Both cameras offer a wide aperture across their lenses, with the Galaxy S25 Ultra featuring 1.7, 3.4, 1.9, and 2.4f apertures, while the Xiaomi 15 Ultra has 2.6, 1.8, 1.6, and 2.2f apertures. Both devices also include built-in optical image stabilization for improved photo quality.

For video recording, both phones can record at a resolution of 4320 x 30 fps. Both devices have a dual-tone LED flash with 2 LEDs, though the Galaxy S25 Ultra has a BSI sensor, while the Xiaomi 15 Ultra does not. Both devices support slow-motion video recording, have built-in HDR modes, and support shooting raw images. They also both include manual exposure, manual ISO, serial shot mode, manual focus, and manual shutter speed. The Galaxy S25 Ultra has an optical zoom of 5x, whereas the Xiaomi 15 Ultra offers a slightly lower optical zoom of 4.3x.

The front cameras also differ, with the Galaxy S25 Ultra featuring a 12 MP front camera with a 2.2f wide aperture, while the Xiaomi 15 Ultra has a higher resolution 32 MP front camera with a 2f aperture. Both front cameras lack a front-facing LED flash and dual-lens setups. The Galaxy S25 Ultra has a DxOMark Mobile score of 146, while the Xiaomi 15 Ultra scores slightly higher at 153. The Xiaomi 15 Ultra also supports Dolby Vision recording, which the Galaxy S25 Ultra does not. Additionally, the Xiaomi 15 Ultra is capable of shooting 360° panoramas, while the Galaxy S25 Ultra cannot. Both devices offer touch autofocus, laser autofocus, and the ability to create in-camera panoramas, with neither supporting 3D photo/video recording capabilities.

Both the Samsung Galaxy S25 Ultra and the Xiaomi 15 Ultra run on Android 15, providing a similar foundation for their operating systems. Both phones come with clipboard warnings, location privacy options, and camera/microphone privacy options, ensuring enhanced security and privacy for users. They also offer theme customization, the ability to block app tracking, and the ability to block cross-site tracking, though the Xiaomi 15 Ultra does not block cross-site tracking, unlike the Galaxy S25 Ultra. Both phones support on-device machine learning, notification permissions, and media pickers, as well as the ability to play games while they download.

The Galaxy S25 Ultra offers additional features like Wi-Fi password sharing, which is not available on the Xiaomi 15 Ultra. Both devices include battery health checks, extra dim modes, focus modes, dynamic theming, app offloading, customizable notifications, Live Text, full-page screenshots, split screen support, and PiP (Picture-in-Picture). The Xiaomi 15 Ultra lacks the ability to be used as a PC, whereas the Galaxy S25 Ultra does support this feature. Both phones do not get direct OS updates, but they do support Quick Start features.

In terms of system-wide features, both devices support widgets, offline voice recognition, voice commands, and multi-user systems. They both track the current position of a mobile device, but the Xiaomi 15 Ultra does not have Wi-Fi password sharing or the ability to be used as a PC. Lastly, neither phone offers Mail Privacy Protection, and both are free and open-source.

The Samsung Galaxy S25 Ultra and Xiaomi 15 Ultra both come with high-capacity batteries, though the Xiaomi 15 Ultra has a larger 6000 mAh battery compared to the 5000 mAh battery of the Galaxy S25 Ultra. Both devices support wireless charging, with the Galaxy S25 Ultra offering a wireless charging speed of 15W, while the Xiaomi 15 Ultra supports faster wireless charging at 80W. Additionally, both phones offer reverse wireless charging; the Galaxy S25 Ultra provides a 4.5W reverse wireless charging speed, whereas the Xiaomi 15 Ultra supports 10W reverse wireless charging.

When it comes to fast charging, the Galaxy S25 Ultra supports 45W charging, while the Xiaomi 15 Ultra offers a significantly faster 90W charging speed. The Galaxy S25 Ultra does not come with a charger in the box, while the Xiaomi 15 Ultra does include a charger. Both devices feature non-removable rechargeable batteries, an ultra power-saving mode, and a battery level indicator.

In terms of battery life, the Galaxy S25 Ultra lasts for 31 hours, which is longer than the 19 hours of battery life provided by the Xiaomi 15 Ultra. Both phones feature rechargeable batteries and have similar battery-related features like an ultra power-saving mode and battery level indicator, but the Xiaomi 15 Ultra provides faster charging and a larger battery capacity.

Both the Samsung Galaxy S25 Ultra and the Xiaomi 15 Ultra lack a 3.5 mm audio jack, but both feature stereo speakers for high-quality sound output. In terms of Bluetooth audio support, both phones support aptX, LDAC, and aptX HD, ensuring compatibility with a wide range of high-quality audio devices. The Xiaomi 15 Ultra, however, has additional support for aptX Adaptive and aptX Lossless, which the Galaxy S25 Ultra does not offer.

When it comes to microphones, the Galaxy S25 Ultra is equipped with 3 microphones, while the Xiaomi 15 Ultra has 4 microphones, likely providing slightly better audio capture and noise reduction capabilities.

Both devices lack a radio, so they do not support FM or other traditional radio services. Overall, while both phones have strong audio capabilities, the Xiaomi 15 Ultra offers more advanced Bluetooth audio support and an additional microphone for enhanced audio performance.

Both the Samsung Galaxy S25 Ultra and the Xiaomi 15 Ultra support 5G, ensuring fast mobile data speeds. They share similar Wi-Fi capabilities, including support for Wi-Fi 4 (802.11n), Wi-Fi 5 (802.11ac), Wi-Fi 6 (802.11ax), Wi-Fi 6E (802.11ax), and Wi-Fi 7 (802.11be). In terms of Bluetooth, the Galaxy S25 Ultra is equipped with Bluetooth 5.4, while the Xiaomi 15 Ultra features the newer Bluetooth 6. Both devices offer NFC, USB Type-C with USB 3.2 support, and are capable of download speeds of 10000 MBits/s and upload speeds of 3500 MBits/s.

When it comes to SIM cards, the Galaxy S25 Ultra supports 2 SIM cards and 2 eSIMs, while the Xiaomi 15 Ultra supports 2 SIM cards but no eSIMs. Both devices include a fingerprint scanner, a gyroscope, GPS, a compass, and a barometer. The Galaxy S25 Ultra also supports ANT+, whereas the Xiaomi 15 Ultra does not. The Xiaomi 15 Ultra additionally includes an infrared sensor, which the Galaxy S25 Ultra lacks. The Galaxy S25 Ultra comes with a stylus, while the Xiaomi 15 Ultra does not.

Both phones have a cellular module, an accelerometer, and support for Galileo. Neither phone includes an HDMI output, a 3D facial recognition system, an iris scanner, motion tracking, optical tracking, or a built-in projector. The Xiaomi 15 Ultra has the added feature of emergency SOS via satellite, which is absent in the Galaxy S25 Ultra. Finally, the head SAR (specific absorption rate) of the Galaxy S25 Ultra is 1.26W/kg, while the Xiaomi 15 Ultra has a lower head SAR of 0.997W/kg.

Both the Samsung Galaxy S25 Ultra and the Xiaomi 15 Ultra come with a video light, making them equipped for better lighting in low-light video situations. Neither device includes sapphire glass for the display, so they may not have the added durability that sapphire offers. Both phones also feature flat displays, as neither has a curved display. Additionally, neither device has an e-paper display, meaning their screens are not optimized for extremely low-power, always-on content.

In summary, the two phones have identical specifications in this miscellaneous group, with both offering video lights, flat displays, and lacking sapphire glass or e-paper displays.