Asus Zenfone 8 vs OnePlus 9RT 5G: A Deep Dive into Compact Power and Rapid Charging

The Asus Zenfone 8 and OnePlus 9RT 5G represent distinct approaches to the flagship smartphone experience. The Zenfone 8 prioritizes a genuinely compact form factor without compromising on core performance, while the 9RT focuses on delivering a smooth, fast experience with an emphasis on rapid charging. Both leverage the Snapdragon 888, but their implementations and surrounding features create a compelling contrast for discerning Android users.
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🏆 Quick Verdict

For the average user prioritizing portability and a balanced experience, the Asus Zenfone 8 emerges as the winner. Its compact size is a significant differentiator, and its 88-hour endurance rating, despite a slower charging speed, offers reliable all-day battery life. The OnePlus 9RT excels in charging speed, but doesn't offer a compelling advantage elsewhere.

PHONES
Phone Names Asus Zenfone 8 OnePlus 9RT 5G
Network
2G bandsGSM 850 / 900 / 1800 / 1900GSM 850 / 900 / 1800 / 1900
3G bandsHSDPA 800 / 850 / 900 / 1700(AWS) / 1900 / 2100HSDPA 800 / 850 / 900 / 1700(AWS) / 1800 / 1900 / 2100
4G bands1, 2, 3, 4, 5, 7, 8, 12, 17, 18, 19, 20, 26, 28, 34, 38, 39, 40, 41, 42 - International1, 2, 3, 4, 5, 7, 8, 12, 17, 18, 19, 20, 26, 28, 34, 38, 39, 40, 41 - Global
5G bands1, 2, 3, 5, 7, 8, 12, 20, 28, 38, 77, 78 SA/NSA - International1, 3, 5, 8, 28, 40, 41, 78 SA/NSA - Global
SpeedHSPA 42.2/5.76 Mbps, LTE (5CA) Cat20 2000/150 Mbps, 5GHSPA 42.2/5.76 Mbps, LTE Cat18 1200/200 Mbps, 5G
TechnologyGSM / HSPA / LTE / 5GGSM / CDMA / HSPA / EVDO / LTE / 5G
 1, 2, 3, 5, 7, 8, 12, 20, 25, 38, 40, 66, 71, 77, 78 SA/NSA - USACDMA2000 1xEV-DO
Launch
Announced2021, May 122021, October 13
StatusAvailable. Released 2021, May 13Available. Released 2021, October 19
Body
BuildGlass front (Gorilla Glass Victus), glass back (Gorilla Glass 3), aluminum frameGlass front (Gorilla Glass 5), glass back (Gorilla Glass 5), aluminum frame
Dimensions148 x 68.5 x 8.9 mm (5.83 x 2.70 x 0.35 in)162.2 x 74.6 x 8.3 mm (6.39 x 2.94 x 0.33 in)
SIMNano-SIM + Nano-SIMNano-SIM + Nano-SIM
Weight169 g (5.96 oz)198.5 g (7.02 oz)
 IP68 dust/water resistant (up to 1.5m for 30 min)-
Display
ProtectionCorning Gorilla Glass VictusCorning Gorilla Glass 5
Resolution1080 x 2400 pixels, 20:9 ratio (~446 ppi density)1080 x 2400 pixels, 20:9 ratio (~397 ppi density)
Size5.9 inches, 84.0 cm2 (~82.9% screen-to-body ratio)6.62 inches, 106.3 cm2 (~87.9% screen-to-body ratio)
TypeSuper AMOLED, 120Hz, HDR10+, 700 nits (HBM), 1100 nits (peak)AMOLED, 120Hz, HDR10+
 Always-on displayAlways-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 13Android 11, upgradable to Android 13, OxygenOS 13
Memory
Card slotNoNo
Internal128GB 6GB RAM, 128GB 8GB RAM, 256GB 8GB RAM, 256GB 12GB RAM, 256GB 16GB RAM128GB 8GB RAM, 256GB 8GB RAM, 256GB 12GB RAM
 UFS 3.1UFS 3.1
Main Camera
Dual64 MP, f/1.8, 26mm (wide), 1/1.73", 0.8µm, PDAF, OIS 12 MP, f/2.2, 112˚, 14mm (ultrawide), 1/2.55", 1.4µm, dual pixel PDAF-
FeaturesLED flash, HDR, panoramaDual-LED flash, HDR, panorama
Quad-50 MP, f/1.8, 24mm (wide), 1/1.56”, 1.0µm, PDAF, OIS 16 MP, f/2.2, 14mm, 123˚ (ultrawide), 1/3.6", 1.0µm 2 MP (macro)
Single-16 MP, f/2.4, (wide), 1/3.06", 1.0µm
Video8K@24fps, 4K@30/60/120fps, 1080p@30/60/240fps, 720p@480fps; gyro-EIS, HDR4K@30/60fps, 1080p@30/60/240fps, Auto HDR, gyro-EIS
Selfie camera
Features-HDR
Single12 MP, f/2.5, 28mm (standard), 1/2.93", 1.22µm, dual pixel PDAF16 MP, f/2.4, (wide), 1/3.06", 1.0µm
Video4K@30fps, 1080p@30/60fps1080p@30fps, gyro-EIS
Sound
3.5mm jack YesNo
35mm jackYesNo
Loudspeaker Yes, with stereo speakersYes, with stereo speakers
 32-bit/384kHz audio-
Comms
Bluetooth5.2, A2DP, LE, aptX HD, aptX Adaptive5.2, A2DP, LE
NFCYesYes
PositioningGPS (L1+L5), GLONASS (L1), BDS (B1I+B1c+B2a), GALILEO (E1+E5a), QZSS (L1+L5), NavIC (L5)GPS (L1+L5), GLONASS (G1), BDS (B1), GALILEO (E1+E5a)
RadioFM radio (market/region dependent)No
USBUSB Type-C 2.0, OTGUSB Type-C 2.0, OTG
WLANWi-Fi 802.11 a/b/g/n/ac/6e, dual-band, Wi-Fi DirectWi-Fi 802.11 a/b/g/n/ac/6, dual-band, Wi-Fi Direct
Features
SensorsFingerprint (under display, optical), accelerometer, gyro, proximity, compassFingerprint (under display, optical), accelerometer, gyro, proximity, compass
Battery
Charging30W wired, PD3.0, 60% in 25 min, 100% in 80 min Reverse wired65W wired, 100% in 29 min
TypeLi-Po 4000 mAhLi-Po 4500 mAh
Misc
ColorsObsidian Black, Horizon SilverHacker Black, Nano Silver, Blue
ModelsZS590KS, ZS590KS-2A007EU, I006DMT2110, MT2111
PriceAbout 290 EURAbout 590 EUR
Tests
Battery life Endurance rating 88h -
Camera Photo / Video-
Display Contrast ratio: Infinite (nominal)-
Loudspeaker -27.9 LUFS (Good) -
Performance AnTuTu: 676001 (v8) | 799738 (v9) GeekBench: 3604 (v5.1) GFXBench: 61fps (ES 3.1 onscreen)-

Asus Zenfone 8

  • Truly compact and pocketable design
  • Excellent 88-hour battery endurance
  • Flagship-level Snapdragon 888 performance

  • Slower 30W charging compared to the 9RT
  • Smaller form factor may lead to thermal throttling

OnePlus 9RT 5G

  • Blazing-fast 65W charging (100% in 29 minutes)
  • Larger display for media consumption
  • Potentially better thermal management due to larger size

  • Larger size compromises one-handed usability
  • Battery endurance not specified, potentially lower than Zenfone 8

Display Comparison

Both the Zenfone 8 and 9RT utilize AMOLED panels, but detailed display specifications beyond the Zenfone 8's 800 nits peak brightness are missing. The Zenfone 8's 'Infinite' contrast ratio suggests a typical AMOLED experience with excellent blacks. The 9RT's display size is larger, impacting one-handed usability. Without refresh rate or resolution data for the 9RT, it's difficult to assess its overall display quality, but the Zenfone 8's compact size and confirmed brightness give it an edge for outdoor visibility.

Camera Comparison

Both phones feature capable camera systems, but detailed sensor information is limited. Both are described as having 'Photo / Video' capabilities. Without specifics on sensor size, aperture, or optical image stabilization (OIS), a direct comparison is difficult. The absence of detail suggests neither phone boasts a groundbreaking camera system. The 9RT's larger size *could* accommodate a larger sensor, but this is speculative. The usefulness of any included macro cameras (often 2MP) is questionable, as image quality is typically low.

Performance

Both devices are powered by the Qualcomm SM8350 Snapdragon 888 5G (5 nm) chipset, featuring an Octa-core CPU configuration (1x2.84 GHz Cortex-X1, 3x2.42 GHz Cortex-A78, 4x1.80 GHz Cortex-A55). This means raw processing power will be nearly identical. However, thermal management is a crucial factor. While both phones share the same chipset, the Zenfone 8's smaller chassis may present greater thermal challenges under sustained load, potentially leading to more aggressive throttling. The 9RT's larger size could offer better passive cooling. RAM configurations are not specified, but both are expected to offer ample RAM for multitasking.

Battery Life

The Zenfone 8 boasts an endurance rating of 88 hours, indicating strong battery life despite not having a massive battery capacity. The OnePlus 9RT 5G significantly differentiates itself with 65W wired charging, achieving a full charge in just 29 minutes. The Zenfone 8 takes 80 minutes to reach 100% with its 30W charging. This charging speed difference is substantial. However, the Zenfone 8's 88-hour endurance suggests efficient power management, potentially offsetting the slower charging for many users. The 9RT's faster charging is ideal for those who frequently need to quickly top up their battery.

Buying Guide

Buy the Asus Zenfone 8 if you need a truly pocketable flagship with excellent performance and don't mind a slightly slower charging experience. It's ideal for one-handed use and users who value a compact design above all else. Buy the OnePlus 9RT 5G if you prioritize the absolute fastest charging speeds and prefer a slightly larger form factor. It's a good choice for power users who frequently top up their battery throughout the day.

Frequently Asked Questions

❓ Will the Snapdragon 888 in the Zenfone 8 overheat during extended gaming sessions?
The Zenfone 8's compact design presents a thermal challenge for the Snapdragon 888. While the chipset is powerful, sustained high loads may lead to throttling to prevent overheating. Expect some performance reduction during prolonged gaming, but the phone should remain usable.
❓ How does the 65W charging on the OnePlus 9RT impact battery health over the long term?
While 65W charging is incredibly fast, it's important to note that consistently using extremely fast charging *can* contribute to slightly faster battery degradation over several years. However, OnePlus implements charging algorithms designed to mitigate this effect, and the convenience of rapid charging often outweighs the minor long-term impact.
❓ Is the Zenfone 8's smaller size a dealbreaker for media consumption?
The Zenfone 8's compact size is its defining feature, but it does mean a smaller display. While perfectly adequate for casual video watching, those who prioritize immersive media experiences may find the 9RT's larger screen more appealing. Consider your typical usage patterns.