OnePlus 15T vs Xiaomi 15 Ultra

OnePlus 15T

The 6.32-inch 165 Hz 1.5K AMOLED panel is the only true 165 Hz compact-flagship display on the market and pairs that refresh rate with a measured 1,800 nits brightness, 460 ppi pixel density, Crystal Shield Glass, and HDR10+/Dolby Vision support. Native 165 Hz support in popular FPS games is a real differentiator. Notebookcheck flags 120.7 Hz PWM dimming that can cause eyestrain for sensitive users.

• The 6.32-inch 165 Hz AMOLED panel achieves a very good 460 ppi pixel density and the advertised maximum brightness of 1,800 nits in standard measurement.
• Display sharpness is plenty competent — sharp, smooth, and easily one of the strongest spec sheets you can get on a compact phone.
• Native 165 Hz support in COD, Delta Force and Peacekeeper Elite makes this the only small-screen flagship pushing a full 165 Hz gaming experience.
• OnePlus claims up to 3,600 nits peak brightness — even on a playground in direct sunlight you can still see everything clearly, no squinting required.
• Specifications confirm a 6.32-inch 1.5K (1216 × 2640) resolution with 165 Hz refresh — a configuration unique to the 15T in the compact class.
• Display backlight flickers at just 120.7 Hz under PWM dimming — low enough that the flickering may cause eyestrain and headaches for sensitive users after extended use.

Xiaomi 15 Ultra

A 6.73-inch 2K AMOLED with curved edges, 120Hz, a 3,200-nit peak and 1,920Hz PWM dimming. Reviewers call it gorgeous and one of the brightest screens around, with the lone caveat that real-world auto-brightness measured lower than the headline number.

• The 6.73-inch display is gorgeous, super sharp and crazy bright — fantastic indoors and out, second only to the Galaxy S25 Ultra in direct sunlight thanks to Samsung's anti-glare tech.
• On paper it has the brightest screen at 3,200 nits (vs 2,600 on the Samsung, 2,000 on the iPhone) and supports 1,920Hz PWM dimming so it flickers much less than its rivals.
• Lab testing clocked ~3,175 nits at 20% APL — basically stare-at-the-sun-and-still-see-your-screen territory.
• The maximum achievable auto-brightness is only around 1,150 nits, which is rather disappointing for this level of phone, though still usable under sunlight.
• It has 3,200 nits peak brightness across a 25% area rather than the usual 1% window — a genuinely usable peak.

OnePlus 15T

Snapdragon 8 Elite Gen 5 paired with 12-16GB LPDDR5X Ultra Pro RAM delivers flagship synthetic scores — Notebookcheck recorded Geekbench multi-core 10,976 and 3DMark Wild Life Unlimited 29,901, on par with the larger Xiaomi 17 and Honor Magic8 Pro Air. The problem is sustained: in the 3DMark Wild Life stress test the GPU drops over 50% and the back of the phone hits 50 °C, which both Notebookcheck and SuperSaf flag as a deal-breaker for long gaming sessions.

• Geekbench 6 multi-core hits 10,976 — flagship-tier and within 1% of the average 8 Elite Gen 5 result, so there is no compromise on the chipset versus larger phones.
• 3DMark Wild Life Unlimited hits 29,901 — 5% above the 8 Elite Gen 5 average and ahead of the Xiaomi 17 with the same chip.
• In the 3DMark stress tests the OnePlus 15T shows a sharp drop in performance of over 50%, which significantly lowers our rating.
• Wildlife Extreme stress test scores swung from 6,990 best loop to 3,743 worst loop in a single run — the chart is 'quite a bit of a bumpy ride' and performance mode did nothing to stabilize it.
• Surface temperatures hit 48.3 °C on the back during stress testing and continued climbing to 50 °C near the camera bump — about 45 °C internal — which seems to be the phone's thermal limit.
• Genshin Impact averaged 60.3 fps over 30 minutes at just 3.2 W power draw, with the phone staying cool to the touch — and Peacekeeper Elite pushed 164.5 fps thanks to native 165 Hz support.
• r/Android's reviewer thread flags the same thermal issue directly: 'Gets kinda hot, over 50 degrees in the corner. This is with its very heavy throttling.'

Xiaomi 15 Ultra

Snapdragon 8 Elite with up to 16GB RAM and UFS 4.1 — flagship-grade and still excellent a year on. Real-world gaming holds ~57–60fps with acceptable power draw, though heavy synthetic stress tests show meaningful throttling.

• Runs Qualcomm's Snapdragon 8 Elite with up to 16GB RAM and 1TB UFS 4.1; 10 months on it's still an extremely well-balanced phone that feels like a true flagship.
• In ~50 minutes of gaming it held a stable ~57–60fps with 4–8W draw — acceptable for the 8 Elite — where some rivals throttle hard and drop to 30fps after 30 minutes.
• After 30 minutes of real gaming with apps closing/reopening the CPU sat around 47°C with no overheating — heat only appears in synthetic 3DMark/throttle benchmarks, not realistic use.
• In a 3DMark stability run it scored ~70–76% stability (lowest loop ~4,335–4,542), holding 20–43fps.
• Under a punishing 60-minute 100-thread CPU throttle test it dropped roughly 40–50% in sustained performance, recovering only slightly better than the S25 Ultra.

OnePlus 15T

This is the section the OnePlus 15T was built to win. The 7,500 mAh silicon-carbon 'Glacier' cell is the largest ever fitted to a true compact phone — 50% bigger than the iPhone 17's pack in a similar footprint. Notebookcheck measured roughly 1.5 days of real-world endurance at 150 cd/m². Wired charging tops out at 100 W, wireless at 50 W. The only friction points are the missing built-in magnets for MagSafe-style alignment and the still-USB-2.0 port.

• OnePlus relies on a silicon-carbon-based battery with a large capacity of 7,500 mAh for its mini flagship — in our practical battery test at 150 cd/m² brightness, the 15T achieved an excellent battery life of nearly 1.5 days.
• 9to5Google's preview confirms the 7,500 mAh cell carries the same 'Glacier' moniker as the OnePlus 15's battery, so the silicon-carbon structure is here too — 200 mAh more than the larger sibling.
• Even though the phone keeps the same compact size, it now packs a massive 7,500 mAh battery — to put that into perspective, the iPhone 17 Pro Max only has around 5,000 mAh, and this is a 6.32-inch phone.
• Battery life is wild for a phone this size and is actually a hair bigger than the one in the OnePlus 15, which has a noticeably larger footprint.
• 100W SuperVOOC wired charging and 50W wireless mean even the huge cell refills fast — getting through two full days on a single charge feels totally realistic.
• There is no native magnetic Qi alignment — wireless charging works, but accessories require a separate magnetic case for MagSafe-style snap-on functionality.
• r/Android's reaction to the battery is unambiguous — 'Incredible battery life makes the compact smartphone competition pale in comparison' is the actual review-thread headline.

Xiaomi 15 Ultra

The global model's ~5,410mAh cell (vs 6,000mAh in China) is the phone's weakest area — many reviewers end the day under 30%, with a notable idle drain — though 90W wired charging fully refills it in roughly an hour and Chinese-variant users report much better longevity.

• The global variant has a smaller 5,410mAh cell vs the 6,000mAh China variant, and most days the phone is around or under 30% by the end of the day — it could have done with a bigger battery.
• With always-on display, 120Hz and intensive camera use it consistently achieved over 15 hours of usage on a single charge in real-world testing.
• On the global/Indian 5,410mAh battery, the in-box 90W charger refills it roughly: 18% in 5 min, 67% in 30 min, 90% in 45 min, and a full charge in about an hour.
• On the Chinese 6,000mAh variant with a power-efficient chip, the battery was still at 78% after not charging for three nights.
• There's a real idle-drain issue — 20 minutes of light morning use can drop 5–6%, and it persists even with extra-dim settings enabled.

OnePlus 15T

The OnePlus 15T ships with ColorOS 16 on Android 16 in China rather than the global OxygenOS, though the two skins are now nearly identical in feel. Update commitments are unclear — OnePlus doesn't publish a timeline for Chinese-market hardware, and even the global OnePlus 15 only commits to 4 years of major Android upgrades. Mind Space (AI-powered productivity vault) and Gemini integration are the headline software features.

• ColorOS 16 comes pre-installed on the 15T instead of OxygenOS — but the differences are minor overall, with German language and Android Auto supported, though no WearOS watches or eSIMs.
• There are question marks over the duration of the updates provided — the manufacturer does not usually provide any information on this for China, though typically a OnePlus 15-class phone should receive security updates for six years.
• OxygenOS 16 (and ColorOS 16 by extension) integrates Gemini with Mind Space — you can ask Gemini about any saved memory and it accesses local content to perform tasks, making it the best on-phone AI integration we have seen.
• Mind Space is the headline AI feature — a digital vault that takes a screenshot of important content and saves it as a card with URL, summary, title and hashtags for contextual search.
• The system feels incredibly smooth — arguably one of the best experiences you can get on Android right now, with useful features for students like meeting summaries and lecture transcription.
• Update commitment trails the competition — even on the global OnePlus 15 the company only promises 4 years of major Android upgrades, well behind Samsung and Google's 7-year commitments.

Xiaomi 15 Ultra

HyperOS (now on the Android 16 / HyperOS 3 track) is the phone's most criticized aspect: it heavily mimics iOS, ships with quirks you must tweak, and carries small persistent bugs — though it adds genuinely useful touches like a Super Island and AI features, and Xiaomi has improved it via updates.

• Out of the box it gives a really iPhone-like feel and you have to go in and change things before it behaves how you want.
• Long-standing requests are still ignored — no combined notification/control center, removed options like front-camera switching while recording video, and the dropped variable aperture.
• HyperOS adds a useful Super Island (tap to expand or switch to a floating window) and direct drag-and-drop into chats, with OS 3 refining the control center.
• Xiaomi's animations are nearly iOS-level and arguably better than stock Android, but the software is still seen as subpar for the Western market.
• Xiaomi now offers a longer software-update commitment (reported up to 6 years) — a meaningful improvement for long-term buyers.