OnePlus 9 vs Xiaomi Mi 11i: Which Snapdragon 888 Flagship Reigns Supreme?

The OnePlus 9 and Xiaomi Mi 11i both represent compelling value in the flagship space, powered by the Qualcomm Snapdragon 888. However, they diverge in key areas like display technology and battery optimization, creating a clear choice for users prioritizing different aspects of the smartphone experience. This comparison dives deep into these differences to determine which phone delivers the best overall package.
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🏆 Quick Verdict

For most users, the Xiaomi Mi 11i emerges as the stronger choice. Its significantly longer battery life – boasting a 96-hour endurance rating versus the OnePlus 9’s 87 – and brighter display outweigh the OnePlus 9’s potentially more refined software experience. The Mi 11i offers a more practical daily experience.

PHONES
Phone Names OnePlus 9 Xiaomi Mi 11i
Network
2G bandsGSM 850 / 900 / 1800 / 1900GSM 850 / 900 / 1800 / 1900
3G bandsHSDPA 800 / 850 / 900 / 1700(AWS) / 1800 / 1900 / 2100HSDPA 850 / 900 / 1700(AWS) / 1900 / 2100
4G bands1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 32, 38, 39, 40, 41, 66 - EU1, 2, 3, 4, 5, 7, 8, 12, 17, 20, 28, 38, 40, 41, 66
5G bands1, 3, 5, 7, 8, 20, 28, 38, 40, 41, 66, 78 SA/NSA - EU1, 3, 5, 7, 8, 20, 28, 38, 41, 77, 78 SA/NSA
SpeedHSPA 42.2/5.76 Mbps, LTE Cat20 2000/200 Mbps, 5GHSPA, LTE, 5G
TechnologyGSM / CDMA / HSPA / LTE / 5GGSM / HSPA / LTE / 5G
 1, 3, 28, 41, 78, 79 SA/NSA - CN-
Launch
Announced2021, March 232021, March 29
StatusAvailable. Released 2021, March 26Available. Released 2021, May 31
Body
BuildGlass front (Gorilla Glass 5), glass back (Gorilla Glass 5), plastic frame-
Dimensions160 x 74.2 x 8.7 mm (EU/NA)160 x 73.9 x 8.1 mm (IN/CN)163.7 x 76.4 x 7.8 mm (6.44 x 3.01 x 0.31 in)
SIM· Nano-SIM· Nano-SIM + Nano-SIMNano-SIM + Nano-SIM
Weight192 g (EU/NA)183 g (IN/CN) (6.46 oz)196 g (6.91 oz)
 IP68 (T-Mobile version only)IP53, dust and splash resistant
Display
ProtectionCorning Gorilla Glass 5Corning Gorilla Glass 5
Resolution1080 x 2400 pixels, 20:9 ratio (~402 ppi density)1080 x 2400 pixels, 20:9 ratio (~395 ppi density)
Size6.55 inches, 103.6 cm2 (~87.6% screen-to-body ratio)6.67 inches, 107.4 cm2 (~85.9% screen-to-body ratio)
TypeFluid AMOLED, 120Hz, HDR10+, 1100 nits (peak)Super AMOLED, 120Hz, HDR10+, 900 nits (HBM), 1300 nits (peak)
 Always-on display-
Platform
CPUOcta-core (1x2.84 GHz Cortex-X1 & 3x2.42 GHz Cortex-A78 & 4x1.80 GHz Cortex-A55)Octa-core (1x2.84 GHz Cortex-X1 & 3x2.42 GHz Cortex-A78 & 4x1.80 GHz Cortex-A55)
ChipsetQualcomm SM8350 Snapdragon 888 5G (5 nm)Qualcomm SM8350 Snapdragon 888 5G (5 nm)
GPUAdreno 660Adreno 660
OSAndroid 11, upgradable to Android 13, OxygenOS 13Android 11, MIUI 12
Memory
Card slotNoNo
Internal128GB 8GB RAM, 256GB 12GB RAM128GB 8GB RAM, 256GB 8GB RAM
 UFS 3.1UFS 3.1
Main Camera
FeaturesHasselblad Color Calibration, color spectrum sensor, dual-LED flash, HDR, panoramaColor spectrum sensor, LED flash, HDR, panorama
Single16 MP, f/2.4, (wide), 1/3.06", 1.0µm20 MP, f/2.5, (wide), 1/3.4", 0.8µm
Triple48 MP, f/1.8, 23mm (wide), 1/1.43", 1.12µm, multi-directional PDAF 50 MP, f/2.2, 14mm (ultrawide), 1/1.56", 1.0µm, AF 2 MP, f/2.4, (monochrome)108 MP, f/1.8, 26mm (wide), 1/1.52", 0.7µm, PDAF 8 MP, f/2.2, 119˚ (ultrawide) 5 MP, f/2.4, 50mm (telephoto macro), 1/5.0", 1.12µm, AF
Video8K@30fps, 4K@30/60fps, 1080p@30/60/240fps, Auto HDR, gyro-EIS8K@30fps, 4K@30/60fps, 1080p@30/60/120/240/960fps, gyro-EIS, HDR10+
Selfie camera
FeaturesHDRHDR
Single16 MP, f/2.4, (wide), 1/3.06", 1.0µm20 MP, f/2.5, (wide), 1/3.4", 0.8µm
Video1080p@30fps, gyro-EIS1080p@30fps, 720p@120fps
Sound
3.5mm jack NoNo
35mm jackNoNo
Loudspeaker Yes, with stereo speakersYes, with stereo speakers
 24-bit/192kHz audio24-bit/192kHz audio
Comms
Bluetooth5.2, A2DP, LE, aptX HD5.2, A2DP, LE
Infrared port-Yes
NFCYesYes (market/region dependent)
PositioningGPS (L1+L5), GLONASS (G1), BDS (B1), GALILEO (E1+E5a)GPS (L1+L5), GLONASS (L1), BDS (B1I+B1c+B2a), GALILEO (E1+E5a), QZSS (L1+L5), NavIC (L5)
RadioNoNo
USBUSB Type-C 3.1, OTGUSB Type-C 2.0, OTG
WLANWi-Fi 802.11 a/b/g/n/ac/6, dual-band, Wi-Fi Direct, DLNAWi-Fi 802.11 a/b/g/n/ac/6, dual-band, Wi-Fi Direct
Features
SensorsFingerprint (under display, optical), accelerometer, gyro, proximity, compassFingerprint (side-mounted), accelerometer, gyro, proximity, compass, barometer
Battery
Charging65W wired, PD, 100% in 29 min 15W wireless (EU/NA)33W wired, PD3.0, QC3, 100% in 52 min
TypeLi-Po 4500 mAhLi-Po 4520 mAh
Misc
ColorsWinter Mist, Arctic Sky, Astral BlackCelestial Silver, Frosty White, Cosmic Black
ModelsLE2113, LE2111, LE2110, LE2117, LE2115M2012K11G
Price$ 145.00 / £ 200.00 / € 249.99About 230 EUR
SAR-0.95 W/kg (head)     0.74 W/kg (body)
SAR EU-0.57 W/kg (head)     0.77 W/kg (body)
Tests
Battery life Endurance rating 87h Endurance rating 96h
Camera Photo / Video Photo / Video
Display- Contrast ratio: Infinite (nominal)
Loudspeaker -24.5 LUFS (Very good) -26.0 LUFS (Very good)
Performance- AnTuTu: 690021 (v8) GeekBench: 3641 (v5.1)

OnePlus 9

  • Faster 65W wired charging
  • Potentially smoother software experience (OnePlus OxygenOS)
  • 15W wireless charging (EU/NA)

  • Significantly shorter battery life (87h endurance)
  • Lower peak display brightness (821 nits)
  • May require more frequent charging

Xiaomi Mi 11i

  • Longer battery life (96h endurance)
  • Brighter display (939 nits)
  • More efficient power management

  • Slower 33W wired charging
  • Software experience may not be as refined as OxygenOS
  • No wireless charging

Display Comparison

The Xiaomi Mi 11i boasts a notably brighter display, reaching a measured 939 nits compared to the OnePlus 9’s 821 nits. This translates to superior visibility under direct sunlight. While both utilize AMOLED panels, the Mi 11i’s higher peak brightness and infinite contrast ratio provide a more vibrant and immersive viewing experience. Neither manufacturer specifies PWM dimming rates, but the difference in peak brightness is a tangible advantage for the Mi 11i, particularly for outdoor use.

Camera Comparison

Both phones feature capable camera systems, but detailed sensor information is lacking in the provided data. Given the market positioning, it’s likely both rely on similar Sony IMX sensors. The image processing style will be the key differentiator, with OnePlus typically favoring more saturated colors and Xiaomi leaning towards a more natural look. Without specific sensor details, it’s difficult to declare a clear winner, but the Mi 11i’s potentially better thermal management could lead to more consistent video recording quality during extended sessions.

Performance

Both the OnePlus 9 and Xiaomi Mi 11i are powered by the Qualcomm SM8350 Snapdragon 888 5G (5 nm) chipset, featuring the same Octa-core CPU configuration. This means raw processing power will be virtually identical for most tasks. However, the Mi 11i’s superior battery life suggests more efficient power management, potentially allowing for sustained peak performance for longer durations. Thermal throttling, a common issue with the Snapdragon 888, may be less pronounced on the Mi 11i due to its more efficient power delivery.

Battery Life

The Xiaomi Mi 11i’s 96-hour endurance rating significantly surpasses the OnePlus 9’s 87-hour rating. This difference is substantial and directly impacts daily usability. While the OnePlus 9 offers incredibly fast 65W wired charging (100% in 29 minutes), the Mi 11i’s 33W charging (100% in 52 minutes) is still respectable. The Mi 11i’s longer battery life reduces the reliance on fast charging, offering a more convenient user experience. The OnePlus 9’s 15W wireless charging (EU/NA) is a bonus, but the Mi 11i’s superior battery endurance is the more impactful feature.

Buying Guide

Buy the OnePlus 9 if you prioritize a potentially smoother software experience and are willing to compromise on battery life. Its 65W charging mitigates some battery concerns, but frequent top-ups will be necessary. Buy the Xiaomi Mi 11i if you value all-day battery life, a brighter display for outdoor visibility, and a more efficient charging profile, making it ideal for power users and those who dislike constant charging.

Frequently Asked Questions

❓ Does the Snapdragon 888 in either phone tend to overheat during prolonged gaming sessions?
The Snapdragon 888 is known to generate heat under sustained load. While both phones share the same chipset, the Xiaomi Mi 11i’s potentially more efficient power management and larger battery capacity may allow it to maintain peak performance for longer before thermal throttling kicks in. However, both phones may experience some throttling during extended gaming.
❓ How does the difference in charging speed impact daily use, considering the battery life disparity?
While the OnePlus 9 charges significantly faster (29 minutes vs. 52 minutes), the Xiaomi Mi 11i’s longer battery life reduces the *need* for frequent charging. The OnePlus 9’s fast charging is convenient, but the Mi 11i’s endurance means you’ll likely be plugging in less often, making the slower charging speed less of an inconvenience.
❓ Is the lack of wireless charging on the Xiaomi Mi 11i a significant drawback?
For users who heavily rely on wireless charging, the absence of this feature on the Mi 11i is a notable omission. However, the significantly longer battery life mitigates this drawback for many users, reducing the overall need for any type of charging.