ASUS Zenfone 12 Ultra vs Xiaomi 15

ASUS Zenfone 12 Ultra

The 6.78-inch Samsung E6 AMOLED panel delivers 2,500 nits peak brightness with LTPO adaptive 1-120Hz (144Hz for gaming). Vivid colors and excellent outdoor readability are let down by FHD+ resolution at a price where competitors offer QHD+, and poor minimum brightness.

• 2,500 nits peak brightness with LTPO 1-120Hz and 144Hz gaming mode — vivid and responsive
• Same display panel as the Zenfone 11 Ultra — no improvement whatsoever year-over-year
• Only FHD+ resolution at EUR 1,099 — competitors offer QHD+ at this price tier

Xiaomi 15

The 6.36-inch 1.5K LTPO OLED is sharp, vibrant, and incredibly bright at 3,200 nits peak (tested up to 3,593 nits HDR). Ultra-narrow 1.38mm bezels and high-frequency PWM dimming above 3,000Hz round out an excellent display package, though OLED smear at lower brightness is a noted concern.

• Peak brightness tested at 3,593 nits in HDR — among the brightest compact phone displays available
• Ultra-narrow 1.38mm bezels with excellent color accuracy in Original Color PRO profile
• OLED smear visible at lower brightness levels (0-70% range) — a recurring user complaint

ASUS Zenfone 12 Ultra

Snapdragon 8 Elite delivers class-leading performance — described as "the fastest phone I used in 2025" by Android Central. The clean, near-stock Android 15 experience with no bloatware makes it one of the most fluid Android phones available. On-device Meta Llama 3 AI processing is private but slow.

• "The fastest phone I used in 2025" — Snapdragon 8 Elite with the best-tuned software on Android
• Clean near-stock Android 15 with zero bloatware — extremely fluid and well-optimized
• On-device Meta Llama 3 AI is privacy-friendly but slow — often faster to just do the task manually
• Aggressive thermal throttling under sustained loads — GPU benchmark scores lower than expected

Xiaomi 15

The Snapdragon 8 Elite with 12GB RAM delivers flagship-tier performance that's smooth and snappy for everyday use, gaming, and multitasking. However, the compact body struggles to dissipate heat under sustained loads, causing notable thermal throttling during extended gaming sessions.

• Snapdragon 8 Elite scores ~2,990 single-core and ~9,114 multi-core on Geekbench 6 — genuinely fast
• Thermal throttling is a real issue — fails to complete 3DMark GPU stress tests and gets uncomfortably hot
• CPU throttles to 72-77% of peak under sustained load — compact chassis limits cooling capacity

ASUS Zenfone 12 Ultra

The standout is the 6-axis Hybrid Gimbal Stabilizer 4.0 which delivers uniquely impressive video stabilization — a 66% improvement over the predecessor. The 50MP main camera is solid in good light, but HDR processing produces visible ghosting artifacts, dynamic range suffers with crushed shadows and clipped highlights, and the overall camera system doesn't compete at this price tier.

• 6-axis Hybrid Gimbal Stabilizer is uniquely excellent for video — best-in-class stabilization
• HDR processing leaves visible ghosting artifacts in photos — a shocking flaw for a 2025 flagship
• Dynamic range issues: shadows frequently crushed, highlights clipped, colors washed out and cold
• "Better than midrange but not flagship level" — not competitive with Galaxy S25 Ultra or Pixel 9 Pro

Xiaomi 15

The triple 50MP Leica system shines with its main sensor and improved 2.6x telephoto, earning a DxOMark score of 146. Leica color profiles produce natural, pleasing images with excellent dynamic range. The ultrawide camera is the clear weakness, with noticeably more noise in low light and no autofocus.

• 50MP main Leica Summilux camera delivers excellent photo quality with natural colors and strong dynamic range
• 2.6x optical telephoto is a meaningful upgrade over the Xiaomi 14 — sharp and versatile
• Ultrawide camera is the weakest link — subpar quality, no autofocus, noticeably more noise in low light
• DxOMark camera score of 146 — good but not class-leading among 2025 flagships

ASUS Zenfone 12 Ultra

The 5,500mAh dual-cell battery delivers excellent all-day endurance that approaches two days for lighter users. 65W wired charging goes from 0-77% in 30 minutes, and Qi 1.3 wireless charging is included. Battery specs are unchanged from the Zenfone 11 Ultra.

• 5,500mAh battery delivers excellent all-day endurance — close to two days for light users
• 65W wired charging reaches 77% in 30 minutes with Qi 1.3 wireless charging support
• Same battery specs as Zenfone 11 Ultra — 65W charging falls behind competitors offering 100W+

Xiaomi 15

A standout category for the Xiaomi 15. The 5,400mAh silicon-carbon battery is a huge upgrade from the Xiaomi 14's 4,610mAh, delivering 16+ hours of active use in GSMArena's tests and consistently 7-8 hours of screen-on time. 90W wired charging goes from 0-100% in about 50 minutes.

• GSMArena Active Use Score of 16:28 hours — excellent endurance for a compact flagship
• 5,400mAh silicon-carbon battery is a massive upgrade from the Xiaomi 14's 4,610mAh — real-world 7-8 hours SOT
• 90W wired charging does 0-100% in about 50 minutes; 50W wireless charging also supported

ASUS Zenfone 12 Ultra

The cleanest Android experience available on a non-Pixel phone, with near-stock Android 15 and zero bloatware. On-device AI via Meta Llama 3 is a privacy-forward approach. But ASUS's devastating update policy — only 2 Android updates and 5 years of security patches — is the phone's single biggest failure at EUR 1,099.

• Cleanest near-stock Android experience on a non-Pixel phone — zero bloatware, extremely fluid
• Only 2 Android OS updates is universally condemned — worst update policy among 2025 flagships
• AI features described as "overkill" and "a lesson in short-term thinking" — often slower than manual alternatives

Xiaomi 15

HyperOS 2 based on Android 15 is fast and fluid with snappy animations and useful AI features. Xiaomi promises 4 major OS updates and 5-6 years of security patches. However, bloatware remains a persistent concern with 193+ removable packages identified, and some system apps contain advertisements.

• HyperOS 2 is fast, fluid, and full of character — one of the more polished Android skins in 2025
• 4 major OS updates + 5-6 years of security patches — competitive but behind Samsung's 7-year commitment
• Significant bloatware with 193+ identifiable packages — some system apps contain advertisements