ASUS Zenfone 12 Ultra vs OnePlus 15T

ASUS Zenfone 12 Ultra

A big, bright 6.78-inch 144Hz AMOLED that's very good in practice — but it's FHD+, not the QHD some expect from an 'Ultra'.

• It's a 6.78-inch LTPO AMOLED at 144Hz, HDR10, with 1,600 nits HBM / 2,500 nits peak at 1080x2400 (20:9), with an always-on display — unchanged from the 11 Ultra.
• Peak brightness hits 2,500 nits with a real-hero ~2,200 nits at 20% APL — though minimum brightness is a bit high at almost 6 nits.
• It's an LTPO 1–120Hz panel with a boosted 144Hz refresh mode available during gaming.
• Calling it an 'Ultra' but shipping no QHD screen is a recurring criticism among buyers.

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.

ASUS Zenfone 12 Ultra

Snapdragon 8 Elite plus ROG-derived cooling makes this a fast, stable performer with no thermal drama.

• The Snapdragon 8 Elite provides excellent burst performance.
• Paired with up to 16GB RAM and UFS 4.0, load times are fast, app switching is seamless and gaming performance is rock solid.
• The most demanding titles held a steady frame rate with no lag and no overheating, impressive given the slim 8.9mm body.
• It carries thermal controls (limit CPU boost, dim brightness, disable 5G when hot) so you can tune sustained performance outdoors.
• Its gaming result was slightly better than the 11 Ultra despite the overall battery regression.

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.

ASUS Zenfone 12 Ultra

Strong real-world endurance from the 5,500mAh cell with fast 65W charging — though lab testing shows a regression versus the 11 Ultra.

• The 5,500mAh battery delivered an easy 10–11 hours of screen-on time across a mix of socials, YouTube and light gaming.
• 65W wired charging takes it 0–100% in roughly 39–45 minutes, with 15W wireless and 10W reverse wired charging.
• GSMArena's testing showed a regression — the 11 Ultra hit ~17h14m of battery life versus ~14h11m for the 12 Ultra.
• It carries an IP68 rating and a large 5,500mAh cell — strong stamina credentials for the class.
• One tester reported no wireless charging on their unit, though most sources confirm 15W wireless is supported.

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.