Between the OnePlus 12 and Xiaomi 15 Ultra, the OnePlus 12 comes out ahead in wired charging and weight, while the Xiaomi 15 Ultra wins on wireless charging and ram. Overall, the OnePlus 12 scores 69.6 and the Xiaomi 15 Ultra scores 73.8 on our Mars Score.
Which should you buy?
The Xiaomi 15 Ultra edges ahead on the Mars Score (69.6 vs 73.8), but the 4.2-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the OnePlus 12 if the display is what you stare at all day — refresh rate, brightness, or sharpness is where the difference will be most visible. The biggest gaps in its favor are wired charging, weight, screen size.
Pick the Xiaomi 15 Ultra if you push the hardware — gaming, on-device AI, heavy multitasking — and the extra compute headroom is worth the trade-offs. Its strongest claims are wireless charging, ram, antutu, among others.
Both ship with comparable main camera, refresh rate, 5g support, so those specs don't separate the two — focus on the differences below.
Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity tells you both are well-rounded; the differences are about trade-offs, not quality.
Why OnePlus 12 wins
- ▲Wired charging — 11.11% more. 100 W vs 90 W.
- ▲Weight — 9.00 g less. 220 vs 229.
- ▲Screen size — 1.34% more. 6.82 " vs 6.73 ".
Why Xiaomi 15 Ultra wins
- ▲Wireless charging — 60.00% more. 80 W vs 50 W.
- ▲RAM — 33.33% more. 16 GB vs 12 GB.
- ▲AnTuTu — 32.04% more. 2720000 vs 2060000.
- ▲Battery capacity — 11.11% more. 6000 mAh vs 5400 mAh.
- ▲Pixel density — 2.35% more. 522 ppi vs 510 ppi.
- ▲Water resistance: IP68 (vs IP65).
Spec comparison
Design
| Spec | OnePlus 12 | Xiaomi 15 Ultra |
|---|---|---|
| Weight | 220 glead | 229 g |
| Thickness | 9.15 mmlead | 9.4 mm |
| Water resistanceⓘ | IP65 | IP68lead |
| Form factor | bar | bar |
Display
| Spec | OnePlus 12 | Xiaomi 15 Ultra |
|---|---|---|
| Screen sizeⓘ | 6.82 "lead | 6.73 " |
| Pixel densityⓘ | 510 ppi | 522 ppilead |
| Refresh rateⓘ | 120 Hz | 120 Hz |
| Peak brightnessⓘ | 4500 nitslead | 3200 nits |
Performance
Cameras
| Spec | OnePlus 12 | Xiaomi 15 Ultra |
|---|---|---|
| Main cameraⓘ | 50 MP | 50 MP |
| Front camera | 32 MP | 32 MP |
| Optical image stabilizationⓘ | true | true |
Battery
| Spec | OnePlus 12 | Xiaomi 15 Ultra |
|---|---|---|
| Battery capacity | 5400 mAh | 6000 mAhlead |
| Wired chargingⓘ | 100 Wlead | 90 W |
| Wireless chargingⓘ | 50 W | 80 Wlead |
Connectivity
| Spec | OnePlus 12 | Xiaomi 15 Ultra |
|---|---|---|
| 5G supportⓘ | true | true |
| Headphone jack | false | false |
| microSD slot | false | false |
Operating System
| Spec | OnePlus 12 | Xiaomi 15 Ultra |
|---|---|---|
| OS | Android | Android |
| Promised OS updates | 4 years | 4 years |
Frequently asked
Which has better battery, OnePlus 12 or Xiaomi 15 Ultra?+
Xiaomi 15 Ultra has 11.1% more battery — 5400 mAh vs 6000 mAh.
Which is lighter, OnePlus 12 or Xiaomi 15 Ultra?+
OnePlus 12 is 9g lighter — 220g vs 229g.
Is OnePlus 12 waterproof?+
OnePlus 12 has an IP65 rating.
Does Xiaomi 15 Ultra support 5G?+
Yes, Xiaomi 15 Ultra supports 5G.
Which has more RAM, OnePlus 12 or Xiaomi 15 Ultra?+
Xiaomi 15 Ultra offers 16GB of RAM.
Which has a better camera, OnePlus 12 or Xiaomi 15 Ultra?+
Xiaomi 15 Ultra has a 50 MP main camera vs 50 MP.
Spec-level deep dives
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