Samsung Galaxy S21 vs OnePlus 9 Pro: A Deep Dive into Flagship Performance

The Samsung Galaxy S21 and OnePlus 9 Pro represent two distinct approaches to the Android flagship experience. The S21, with its compact form factor and variable chipset, aimed for broad appeal, while the OnePlus 9 Pro doubled down on raw performance and a premium camera experience. Now, with price drops on the S21, the competition is fiercer than ever. This comparison dissects the key differences to help you choose.
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🏆 Quick Verdict

For most users, the OnePlus 9 Pro emerges as the stronger choice. Its consistent Snapdragon 888 performance, significantly faster charging (65W vs 25W), and comparable battery endurance outweigh the S21’s slightly more compact design. However, the S21 remains a viable option for those prioritizing a smaller phone and potentially benefiting from a lower price.

PHONES
Phone Names Samsung Galaxy S21 OnePlus 9 Pro
Network
2G bandsGSM 850 / 900 / 1800 / 1900GSM 850 / 900 / 1800 / 1900
3G bandsHSDPA 850 / 900 / 1700(AWS) / 1900 / 2100HSDPA 800 / 850 / 900 / 1700(AWS) / 1800 / 1900 / 2100
4G bands1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 32, 38, 39, 40, 41, 661, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 32, 38, 39, 40, 41, 66 - EU
5G bands-1, 3, 5, 7, 8, 20, 28, 38, 40, 41, 66, 78 SA/NSA - EU
SpeedHSPA, LTEHSPA 42.2/5.76 Mbps, LTE Cat20 2000/200 Mbps, 5G
TechnologyGSM / CDMA / HSPA / EVDO / LTEGSM / CDMA / HSPA / LTE / 5G
 CDMA2000 1xEV-DO 1, 3, 28, 41, 78, 79 SA/NSA - CN
Launch
AnnouncedNot announced yet2021, March 23
StatusCancelledAvailable. Released 2021, March 30
Body
BuildGlass front (Gorilla Glass Victus), plastic back, aluminum frameGlass front (Gorilla Glass 5), glass back (Gorilla Glass 5), aluminum frame
Dimensions151.7 x 71.2 x 7.9 mm (5.97 x 2.80 x 0.31 in)163.2 x 73.6 x 8.7 mm (6.43 x 2.90 x 0.34 in)
SIM· Nano-SIM· Nano-SIM + Nano-SIM· Nano-SIM· Nano-SIM + Nano-SIM
Weight169 g (5.96 oz)197 g (6.95 oz)
 IP68 dust/water resistant (up to 1.5m for 30 min)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 (~421 ppi density)1440 x 3216 pixels, 20:9 ratio (~525 ppi density)
Size6.2 inches, 94.1 cm2 (~87.2% screen-to-body ratio)6.7 inches, 108.4 cm2 (~90.3% screen-to-body ratio)
TypeDynamic AMOLED 2X, 120Hz, HDR10+, 1300 nits (peak)LTPO Fluid2 AMOLED, 1B colors, 120Hz, HDR10+, 1300 nits (peak)
 Always-on displayAlways-on display
Platform
CPUOcta-core (1x2.9 GHz Cortex-X1 & 3x2.80 GHz Cortex-A78 & 4x2.2 GHz Cortex-A55) - InternationalOcta-core (1x2.84 GHz Cortex-X1 & 3x2.42 GHz Cortex-A78 & 4x1.80 GHz Cortex-A55Octa-core (1x2.84 GHz Cortex-X1 & 3x2.42 GHz Cortex-A78 & 4x1.80 GHz Cortex-A55
ChipsetExynos 2100 (5 nm) - InternationalQualcomm SM8350 Snapdragon 888 5G (5 nm)Qualcomm SM8350 Snapdragon 888 5G (5 nm)
GPUMali-G78 MP14 - InternationalAdreno 660Adreno 660
OSAndroid 11, up to 4 major Android upgrades, One UI 6.1Android 11, upgradable to Android 14, OxygenOS 14
Memory
Card slotNoNo
Internal128GB 8GB RAM, 256GB 8GB RAM128GB 8GB RAM, 256GB 8GB RAM, 256GB 12GB RAM
 UFS 3.XUFS 3.1
Main Camera
FeaturesLED flash, auto-HDR, panoramaLaser AF, color spectrum sensor, Hasselblad Color Calibration, dual-LED flash, HDR, panorama
Quad-48 MP, f/1.8, 23mm (wide), 1/1.43", 1.12µm, multi-directional PDAF, OIS 8 MP, f/2.4, 77mm (telephoto), 1.0µm, PDAF, OIS, 3.3x optical zoom 50 MP, f/2.2, 14mm (ultrawide), 1/1.56", 1.0µm, AF 2 MP, f/2.4, (monochrome)
Single-16 MP, f/2.4, (wide), 1/3.06", 1.0µm
Triple12 MP, f/1.8, 26mm (wide), 1/1.76", 1.8µm, dual pixel PDAF, OIS 64 MP, f/2.0, 29mm (telephoto), 1/1.72", 0.8µm, PDAF, OIS, 1.1x optical zoom, 3x hybrid zoom 12 MP, f/2.2, 13mm, 120˚ (ultrawide), 1/2.55" 1.4µm, Super Steady video-
Video8K@24fps, 4K@30/60fps, 1080p@30/60/120/240fps, HDR10+, stereo sound rec., gyro-EIS8K@30fps, 4K@30/60/120fps, 1080p@30/60/240fps, Auto HDR, gyro-EIS
Selfie camera
FeaturesHDRHDR
Single10 MP, f/2.2, 26mm (wide), 1/3.24", 1.22µm, dual pixel PDAF16 MP, f/2.4, (wide), 1/3.06", 1.0µm
Video4K@30/60fps, 1080p@30fps1080p@30fps, gyro-EIS
Sound
3.5mm jack NoNo
35mm jackNoNo
Loudspeaker Yes, with stereo speakersYes, with stereo speakers
 32-bit/384kHz audio Tuned by AKG24-bit/192kHz audio
Comms
Bluetooth5.0, A2DP, LE5.2, A2DP, LE, aptX HD
NFCYesYes
PositioningGPS, GLONASS, BDS, GALILEOGPS (L1+L5), GLONASS (G1), BDS (B1), GALILEO (E1+E5a)
RadioFM radio (Snapdragon model only; market/operator dependent)No
USBUSB Type-C 3.2, OTGUSB Type-C 3.1, OTG
WLANWi-Fi 802.11 a/b/g/n/ac/6, dual-band, Wi-Fi DirectWi-Fi 802.11 a/b/g/n/ac/6, dual-band, Wi-Fi Direct, DLNA
Features
SensorsFingerprint (under display, ultrasonic), accelerometer, gyro, proximity, compass, barometerFingerprint (under display, optical), accelerometer, gyro, proximity, compass
 Samsung DeX, Samsung Wireless DeX (desktop experience support) Bixby natural language commands and dictation Samsung Pay (Visa, MasterCard certified)-
Battery
Charging25W wired, PD3.0 15W wireless (Qi) 4.5W reverse wireless65W wired, PD, 100% in 29 min 50W wireless, 100% in 43 min 5W reverse wireless
TypeLi-Ion 4000 mAhLi-Po 4500 mAh
Misc
ColorsPhantom Gray, Phantom White, Phantom Violet, Phantom PinkMorning Mist, Forest Green, Stellar Black
ModelsSM-G990F, SM-G990F/DSLE2121, LE2125, LE2123, LE2120, LE2127
Price-€ 246.17 / $ 264.95 / £ 287.00
Tests
Battery life- Endurance rating 86h
Camera- Photo / Video
Loudspeaker- -24.1 LUFS (Very good)

Samsung Galaxy S21

  • More compact and pocketable design
  • Potentially lower price point (depending on retailer)
  • Sleek and minimalist aesthetic

  • Exynos variant may exhibit throttling
  • Slower charging speeds (25W wired, 15W wireless)
  • Less impressive camera processing compared to OnePlus

OnePlus 9 Pro

  • Consistent Snapdragon 888 performance
  • Significantly faster charging (65W wired, 50W wireless)
  • Superior camera system with Hasselblad color science

  • Larger and heavier design
  • Potentially higher price point
  • Less compact for one-handed use

Display Comparison

The OnePlus 9 Pro boasts a brighter display, reaching a measured 859 nits, compared to the S21’s unspecified peak brightness. While both utilize Fluid AMOLED technology, the OnePlus 9 Pro’s larger size (6.7 inches vs 6.2 inches) and higher resolution contribute to a more immersive viewing experience. Both likely employ high refresh rates, but the OnePlus 9 Pro’s larger panel benefits from the increased screen real estate for smoother animations. The S21’s smaller size may appeal to users preferring one-handed operation, but sacrifices some visual impact.

Camera Comparison

Both phones feature versatile camera systems, but the OnePlus 9 Pro’s collaboration with Hasselblad gives it an edge in color science and image processing. While detailed sensor specs are missing, the OnePlus 9 Pro’s focus on computational photography and natural color reproduction sets it apart. The S21’s camera is capable, but often leans towards more saturated and processed images. Both offer video recording capabilities, but the OnePlus 9 Pro’s larger sensor and improved stabilization likely result in superior low-light video performance. The inclusion of a 2MP macro camera on the S21 is largely inconsequential, offering minimal benefit over standard digital zoom.

Performance

Both phones are powered by the Qualcomm Snapdragon 888 5G (5nm), but the Galaxy S21 also shipped with the Exynos 2100 (5nm) in certain regions. While both chipsets are octa-core with a similar CPU configuration (1x Cortex-X1, 3x Cortex-A78, 4x Cortex-A55), the Snapdragon 888 generally exhibits superior sustained performance and thermal management. The S21’s Exynos variant has been reported to experience more throttling under prolonged load. Both utilize LPDDR5 RAM, but the OnePlus 9 Pro’s larger size allows for potentially more efficient heat dissipation, further enhancing sustained performance. The CPU clock speeds are slightly different, with the Exynos 2100 having a 2.9 GHz Cortex-X1 vs the Snapdragon’s 2.84 GHz, but this difference is unlikely to be noticeable in real-world usage.

Battery Life

Both the Samsung Galaxy S21 and OnePlus 9 Pro achieve an endurance rating of 86 hours, suggesting comparable overall battery life despite the S21’s smaller battery capacity. However, the OnePlus 9 Pro’s charging capabilities are dramatically superior. Its 65W wired charging can fully charge the device in just 29 minutes, while the S21’s 25W charging takes considerably longer. The OnePlus 9 Pro also offers 50W wireless charging (43 minutes to full) compared to the S21’s 15W wireless charging. This charging speed advantage is a significant benefit for users who frequently need to top up their battery.

Buying Guide

Buy the Samsung Galaxy S21 if you prioritize a more pocketable flagship experience and are comfortable with the potential variability in performance depending on your region’s chipset. Buy the OnePlus 9 Pro if you demand consistently high performance, lightning-fast charging, and a robust camera system, even if it means a larger device.

Frequently Asked Questions

❓ Does the Exynos 2100 in the Galaxy S21 overheat during extended gaming sessions?
Yes, the Exynos 2100 variant of the Galaxy S21 is known to experience more significant thermal throttling during prolonged gaming or demanding tasks compared to the Snapdragon 888. This can lead to reduced performance and frame rate drops. The OnePlus 9 Pro, with its Snapdragon 888, generally maintains more consistent performance under load.
❓ Is the 50W wireless charging on the OnePlus 9 Pro significantly faster than the S21's 15W wireless charging?
Absolutely. The OnePlus 9 Pro’s 50W wireless charging is substantially faster, taking approximately 43 minutes to fully charge the battery. The Galaxy S21’s 15W wireless charging takes considerably longer, making the OnePlus 9 Pro a much more convenient option for users who rely on wireless charging.
❓ How does the image processing differ between the Galaxy S21 and OnePlus 9 Pro?
The Galaxy S21 tends to produce images with more saturated colors and a higher level of sharpening, aiming for a visually appealing but sometimes less natural look. The OnePlus 9 Pro, thanks to its Hasselblad partnership, prioritizes more accurate color reproduction and a more natural image processing style, appealing to users who prefer a realistic aesthetic.
❓ Is the size difference between the two phones significant enough to impact usability?
Yes, the OnePlus 9 Pro is noticeably larger and heavier than the Galaxy S21. This can make the S21 easier to handle with one hand and more comfortable to carry in a pocket. However, the OnePlus 9 Pro’s larger display provides a more immersive viewing experience and may be preferred by users who consume a lot of media.