OnePlus 9 Pro vs Samsung Galaxy S21 Ultra: Which Flagship Reigns Supreme?

The OnePlus 9 Pro and Samsung Galaxy S21 Ultra represent the pinnacle of Android smartphone technology from 2021, but cater to slightly different priorities. While the S21 Ultra aimed for a complete package with a versatile camera system and expansive display, the OnePlus 9 Pro focused on delivering a fast, fluid experience with incredibly rapid charging. Now, with price drops on both, the decision isn't as clear-cut. This comparison dives deep into the specifics to determine which phone offers the best value today.
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🏆 Quick Verdict

For most users, the Samsung Galaxy S21 Ultra 5G emerges as the stronger overall choice. Its significantly longer battery life (114h vs 86h) and brighter display (1023 nits vs 859 nits) provide a more consistently premium experience, even if charging isn't as blazing fast as the OnePlus 9 Pro.

PHONES
Phone Names OnePlus 9 Pro Samsung Galaxy S21 Ultra 5G
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, 13, 14, 18, 19, 20, 25, 26, 28, 30, 38, 39, 40, 41, 46, 48, 66, 71 - SM-G998U1
5G bands1, 3, 5, 7, 8, 20, 28, 38, 40, 41, 66, 78 SA/NSA - EU2, 5, 25, 41, 66, 71, 260, 261 SA/NSA/Sub6/mmWave - SM-G998U1
SpeedHSPA 42.2/5.76 Mbps, LTE Cat20 2000/200 Mbps, 5GHSPA 42.2/5.76 Mbps, LTE (7CA) Cat20 2000/200 Mbps, 5G (5+ Gbps DL)
TechnologyGSM / CDMA / HSPA / LTE / 5GGSM / CDMA / HSPA / EVDO / LTE / 5G
 1, 3, 28, 41, 78, 79 SA/NSA - CN1, 3, 5, 7, 8, 20, 28, 38, 40, 41, 66, 77, 78 SA/NSA/Sub6 - SM-G998B
Launch
Announced2021, March 232021, January 14
StatusAvailable. Released 2021, March 30Available. Released 2021, January 29
Body
BuildGlass front (Gorilla Glass 5), glass back (Gorilla Glass 5), aluminum frameGlass front (Gorilla Glass Victus), glass back (Gorilla Glass Victus), aluminum frame
Dimensions163.2 x 73.6 x 8.7 mm (6.43 x 2.90 x 0.34 in)165.1 x 75.6 x 8.9 mm (6.5 x 2.98 x 0.35 in)
SIM· Nano-SIM· Nano-SIM + Nano-SIM· Nano-SIM + eSIM· Nano-SIM + Nano-SIM + eSIM (max 2 at a time)
Weight197 g (6.95 oz)227 g (Sub6), 229 g (mmWave) (8.01 oz)
 IP68 dust/water resistant (up to 1.5m for 30 min)IP68 dust/water resistant (up to 1.5m for 30 min) Stylus support
Display
ProtectionCorning Gorilla Glass 5Corning Gorilla Glass Victus
Resolution1440 x 3216 pixels, 20:9 ratio (~525 ppi density)1440 x 3200 pixels, 20:9 ratio (~515 ppi density)
Size6.7 inches, 108.4 cm2 (~90.3% screen-to-body ratio)6.8 inches, 112.1 cm2 (~89.8% screen-to-body ratio)
TypeLTPO Fluid2 AMOLED, 1B colors, 120Hz, HDR10+, 1300 nits (peak)Dynamic AMOLED 2X, 120Hz, HDR10+, 1500 nits (peak)
 Always-on displayAlways-on display
Platform
CPUOcta-core (1x2.84 GHz Cortex-X1 & 3x2.42 GHz Cortex-A78 & 4x1.80 GHz Cortex-A55Octa-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-A55) - USA/China
ChipsetQualcomm SM8350 Snapdragon 888 5G (5 nm)Exynos 2100 (5 nm) - InternationalQualcomm SM8350 Snapdragon 888 5G (5 nm) - USA/China
GPUAdreno 660Mali-G78 MP14 - InternationalAdreno 660 - USA/China
OSAndroid 11, upgradable to Android 14, OxygenOS 14Android 11, up to 4 major Android upgrades, One UI 6.1
Memory
Card slotNoNo
Internal128GB 8GB RAM, 256GB 8GB RAM, 256GB 12GB RAM128GB 8GB RAM, 128GB 12GB RAM, 256GB 12GB RAM, 256GB 16GB RAM, 512GB 12GB RAM, 512GB 16GB RAM
 UFS 3.1UFS 3.1
Main Camera
FeaturesLaser AF, color spectrum sensor, Hasselblad Color Calibration, dual-LED flash, HDR, panoramaLaser AF, LED flash, auto-HDR, panorama
Quad48 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)108 MP, f/1.8, 24mm (wide), 1/1.33", 0.8µm, PDAF, OIS 10 MP, f/2.4, 72mm (telephoto), 1/3.24", 1.22µm, dual pixel PDAF, OIS, 3x optical zoom 10 MP, f/4.9, 240mm (periscope telephoto), 1/3.24", 1.22µm, dual pixel PDAF, OIS, 10x optical zoom 12 MP, f/2.2, 13mm (ultrawide), 1/2.55", 1.4µm, dual pixel PDAF, Super Steady video
Single16 MP, f/2.4, (wide), 1/3.06", 1.0µm-
Video8K@30fps, 4K@30/60/120fps, 1080p@30/60/240fps, Auto HDR, gyro-EIS8K@24fps, 4K@30/60fps, 1080p@30/60/120/240fps, HDR10+, stereo sound rec., gyro-EIS
Selfie camera
FeaturesHDRHDR
Single16 MP, f/2.4, (wide), 1/3.06", 1.0µm40 MP, f/2.2, 26mm (wide), 1/2.8", 0.7µm, PDAF
Video1080p@30fps, gyro-EIS4K@30/60fps, 1080p@30fps
Sound
3.5mm jack NoNo
35mm jackNoNo
Loudspeaker Yes, with stereo speakersYes, with stereo speakers
 24-bit/192kHz audio32-bit/384kHz audio Tuned by AKG
Comms
Bluetooth5.2, A2DP, LE, aptX HD5.2, A2DP, LE
NFCYesYes
PositioningGPS (L1+L5), GLONASS (G1), BDS (B1), GALILEO (E1+E5a)GPS, GLONASS, BDS, GALILEO
RadioNoFM radio (Snapdragon model only; market/operator dependent)
USBUSB Type-C 3.1, OTGUSB Type-C 3.2, 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/6e, dual-band, Wi-Fi Direct
Features
SensorsFingerprint (under display, optical), accelerometer, gyro, proximity, compassFingerprint (under display, ultrasonic), accelerometer, gyro, proximity, compass, barometer
 -Samsung DeX, Samsung Wireless DeX (desktop experience support) Bixby natural language commands and dictation Samsung Pay (Visa, MasterCard certified) Ultra Wideband (UWB) support
Battery
Charging65W wired, PD, 100% in 29 min 50W wireless, 100% in 43 min 5W reverse wireless25W wired, PD3.0 15W wireless (Qi) 4.5W reverse wireless
TypeLi-Po 4500 mAhLi-Ion 5000 mAh
Misc
ColorsMorning Mist, Forest Green, Stellar BlackPhantom Black, Phantom Silver, Phantom Titanium, Phantom Navy, Phantom Brown, Navy
ModelsLE2121, LE2125, LE2123, LE2120, LE2127SM-G998B, SM-G998B/DS, SM-G998U, SM-G998U1, SM-G998W, SM-G998N, SM-G9980
Price€ 246.17 / $ 264.95 / £ 287.00$ 240.01 / C$ 353.20 / £ 202.99 / € 264.99
SAR-0.77 W/kg (head)     1.02 W/kg (body)
SAR EU-0.71 W/kg (head)     1.58 W/kg (body)
Pricing
128GB 12GB RAM-$ 384.99
256GB 12GB RAM-$ 998.00
512GB 12GB RAM-$ 1,179.99
RENEWED-$ 459.00
Tests
Battery life Endurance rating 86h Endurance rating 114h
Camera Photo / Video Photo / Video
Display- Contrast ratio: Infinite (nominal)
Loudspeaker -24.1 LUFS (Very good) -25.5 LUFS (Very good)
Performance- AnTuTu: 657150 (v8) GeekBench: 3518 (v5.1) GFXBench: 33fps (ES 3.1 onscreen)

OnePlus 9 Pro

  • Blazing-fast 65W wired charging
  • Smooth and responsive software experience
  • Hasselblad-tuned color science

  • Shorter battery life compared to S21 Ultra
  • Display not as bright as S21 Ultra
  • Less versatile camera system

Samsung Galaxy S21 Ultra 5G

  • Exceptional battery life (114h endurance)
  • Brighter and more vibrant display
  • More versatile camera system with superior zoom

  • Slower charging speeds (25W wired)
  • Exynos variant may exhibit more thermal throttling
  • Software can feel bloated compared to OnePlus

Display Comparison

The Samsung Galaxy S21 Ultra boasts a significantly brighter display, peaking at 1023 nits compared to the OnePlus 9 Pro’s 859 nits. This translates to better visibility outdoors under direct sunlight. While both utilize vibrant AMOLED panels, the S21 Ultra’s ‘Infinite’ contrast ratio suggests deeper blacks and a more immersive viewing experience. Both phones offer smooth scrolling with 120Hz refresh rates, but the S21 Ultra’s adaptive refresh rate technology (LTPO) dynamically adjusts the refresh rate to conserve battery life, a feature absent on the OnePlus 9 Pro.

Camera Comparison

Both phones excel in photography, but approach it differently. While both offer versatile camera systems, the S21 Ultra’s larger main sensor and dual-telephoto lens setup provide greater zoom capabilities and flexibility. The S21 Ultra’s 108MP main sensor captures more detail, while its 10x optical zoom lens allows for significantly closer shots. Both phones are capable of recording high-quality video, but the S21 Ultra’s superior stabilization and dynamic range give it an advantage. The OnePlus 9 Pro’s collaboration with Hasselblad focuses on color science, but the S21 Ultra’s overall camera versatility is more compelling.

Performance

Both the OnePlus 9 Pro and the USA/China variant of the Samsung Galaxy S21 Ultra utilize the Qualcomm Snapdragon 888 5G (5nm). However, international versions of the S21 Ultra ship with the Exynos 2100. While both chipsets are comparable, the Snapdragon 888 generally exhibits slightly better sustained performance and thermal management. The S21 Ultra’s CPU features a marginally higher clock speed on its prime core (2.9 GHz vs 2.84 GHz), but this difference is unlikely to be noticeable in everyday use. Both phones feature 12GB of RAM, ensuring smooth multitasking. The real-world performance difference will likely be minimal for most users, but the Snapdragon variant of the S21 Ultra has a slight edge.

Battery Life

The Samsung Galaxy S21 Ultra’s 114-hour endurance rating significantly surpasses the OnePlus 9 Pro’s 86-hour rating. This difference is primarily due to the S21 Ultra’s larger battery capacity and more efficient display technology. While the OnePlus 9 Pro boasts incredibly fast 65W wired charging (0-100% in 29 minutes) and 50W wireless charging (0-100% in 43 minutes), the S21 Ultra’s 25W wired charging is considerably slower. However, the S21 Ultra’s longer battery life often negates the need for such rapid charging.

Buying Guide

Buy the OnePlus 9 Pro if you prioritize incredibly fast charging – reaching 100% in just 29 minutes – and a streamlined software experience. It’s ideal for users who frequently top up their phones and value simplicity. Buy the Samsung Galaxy S21 Ultra 5G if you need all-day battery life, a more versatile camera system, and a brighter, more vibrant display. It’s the better choice for power users, content creators, and those who demand the most from their smartphone.

Frequently Asked Questions

❓ Does the Exynos 2100 chip in the international S21 Ultra overheat during intensive tasks like gaming?
While the Exynos 2100 is a capable chip, it is known to run slightly warmer than the Snapdragon 888, potentially leading to thermal throttling during prolonged gaming sessions. However, Samsung’s software optimizations and the phone’s cooling system mitigate this issue to a degree, and most users won’t experience significant performance drops.
❓ Is the 2MP macro camera on either phone actually useful for taking detailed close-up shots?
Generally, the 2MP macro cameras on both phones are limited by their low resolution and lack of optical image stabilization. While they can capture close-up shots, the image quality is often subpar compared to using the main sensor with digital zoom. They are more of a marketing feature than a genuinely useful tool.
❓ Can the Samsung Galaxy S21 Ultra consistently maintain 60fps in demanding games like PUBG Mobile at maximum settings?
Yes, the Snapdragon 888 variant of the S21 Ultra can consistently maintain 60fps in PUBG Mobile at maximum settings. The Exynos variant may experience occasional frame drops, but overall performance remains smooth and playable. Both phones offer excellent gaming performance.
❓ How does the OnePlus 9 Pro's Warp Charge 65T compare to other fast charging technologies?
Warp Charge 65T is among the fastest wired charging technologies available, reaching 100% in just 29 minutes. It's significantly faster than the S21 Ultra's 25W charging and comparable to other ultra-fast charging solutions like Xiaomi's 67W or 120W charging. The OnePlus 9 Pro also supports 50W wireless charging, which is also faster than the S21 Ultra's 15W wireless charging.