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Xiaomi Redmi K20 vs Samsung Galaxy A51

Here we compared two mid-range smartphones: the 6.39-inch Xiaomi Redmi K20 (with Qualcomm Snapdragon 730) that was released on May 28, 2019, against the Samsung Galaxy A51, which is powered by Exynos 9 Octa 9611 and came out 6 months after. On this page, you will find tests, full specs, strengths, and weaknesses of each of the gadgets.

Key differences

An overview of the main advantages of each smartphone
Reasons to consider the Xiaomi Redmi K20
  • The rear camera has a 2x optical zoom
  • Shows 16% longer battery life (100 vs 86 hours)
  • 11% better performance in AnTuTu Benchmark (215K versus 193K)
  • Faster storage type - UFS 2.1 versus UFS 2.0
  • More energy-efficient CPU – Snapdragon 730
  • 54% faster in single-core GeekBench 5 test: 542 and 352 points
Reasons to consider the Samsung Galaxy A51
  • Expandable storage via MicroSD card up to 512GB
  • More recent OS version: Android 11 versus 10
  • Supports Dolby Atmos sound technology
  • Weighs 19 grams less
  • The phone is 6-months newer
  • The front-facing camera can record video at 4K

Review

Display
Screen quality, color accuracy, brightness
Performance
CPU/GPU performance in apps and games
Battery
Battery life, charging type and speed
Camera
Photo and video recording quality
Connectivity
Networks, ports, data transmission
NanoReview score
Final comparison evaluation

Value for money

You can enter your local price of these phones (in USD or any other currency) and click on the "Calculate" button to see which one has a better value for money.
Price

Tests and specifications

Comparison table of technical specifications and tests
Phone:
vs

Display

Type Super AMOLED Super AMOLED
Size 6.39 inches 6.5 inches
Resolution 1080 x 2340 pixels 1080 x 2400 pixels
Aspect ratio 19.5:9 20:9
PPI 403 ppi 405 ppi
Refresh rate 60 Hz 60 Hz
HDR support Yes, HDR10 No
Screen protection Corning Gorilla Glass 5 Corning Gorilla Glass 3
Screen-to-body ratio 86.1% 87.4%
Display features - Always-On Display - Always-On Display
Display tests
RGB color space - 98.8%
PWM - 242 Hz
Response time - 25 ms
Contrast - ∞ Infinity
Max. Brightness
Redmi K20 +1%
655 nits
648 nits
Sources: NotebookCheck [1]

Design and build

Height 156.7 mm (6.17 inches) 158.5 mm (6.24 inches)
Width 74.3 mm (2.93 inches) 73.6 mm (2.9 inches)
Thickness 8.8 mm (0.35 inches) 7.9 mm (0.31 inches)
Weight 191 gramm (6.74 oz) 172 gramm (6.07 oz)
Waterproof No No
Rear material Glass Plastic
Frame material Metal Plastic
Colors Black, Blue, Red White, Black
Fingerprint scanner Yes, in-display Yes, in-display
Screen-to-body ratio
86.1%
87.4%

Performance

Tests of Xiaomi Redmi K20 and Samsung Galaxy A51 in the benchmarks
SoC
Chipset Qualcomm Snapdragon 730 Samsung Exynos 9 Octa 9611
Max. clock 2200 MHz 2300 MHz
CPU cores 8 (2 + 6) 8 (4 + 4)
Architecture - 6 cores at 1.8 GHz: Kryo 470 Silver (Cortex-A55)
- 2 cores at 2.2 GHz: Kryo 470 Gold (Cortex-A76)
- 4 cores at 1.7 GHz: Cortex-A53
- 4 cores at 2.3 GHz: Cortex-A73
Lithography process 8 nanometers 10 nanometers
Graphics Adreno 618 Mali-G72 MP3
GPU clock 500 MHz 850 MHz
FLOPS ~386 GFLOPS ~259 GFLOPS
Memory
RAM size 6, 8 GB 4, 6 GB
Memory type LPDDR4X LPDDR4X
Memory clock 1866 MHz 1866 MHz
Channels 2 2
Storage
Storage size 64, 128, 256 GB 64, 128 GB
Storage type UFS 2.1 UFS 2.0
Memory card No MicroSD
Memory card max. size - Up to 512 GB

Benchmarks

Geekbench 5 (Single-Core)
Redmi K20 +54%
542
Geekbench 5 (Multi-Core)
Redmi K20 +28%
1664
1299
AnTuTu Benchmark 7
Redmi K20 +96%
223320
113830
AnTuTu Benchmark 8
Redmi K20 +11%
215593
193889

Software

Operating system Android 9.0 (Can be upgraded to Android 10) Android 10 (Can be upgraded to Android 11)
ROM MIUI 12 One UI 3.0
OS size 11.3 GB 23 GB

Battery

Specifications
Capacity 4000 mAh 4000 mAh
Charge power 18 W 15 W
Battery type Li-Po Li-Po
Replaceable No No
Wireless charging No No
Reverse charging No No
Fast charging Yes, Quick Charge 4.0 (50% in 30 min) Yes (40% in 35 min)
Full charging time 1:25 hr 1:50 hr

Battery life tests

Web browsing (Wi-Fi)
11:35 hr
Galaxy A51 +16%
13:21 hr
Watching videos (Player)
Redmi K20 +21%
17:19 hr
14:22 hr
Talk (3G)
Redmi K20 +54%
33:20 hr
21:51 hr

Camera

Specs and camera test of smartphones
Main camera
Matrix 48 megapixels 48 megapixels
Image resolution 8000 x 6000 8000 x 6000
Zoom Optical, 2x Digital
Flash Dual LED LED
Stabilization Digital Digital
8K video recording No No
4K video recording Up to 30FPS Up to 30FPS
1080p video recording Up to 240FPS Up to 30FPS
Slow motion 960 FPS (1080p) 960 FPS (720p)
Angle of widest lens 124° 120°
Lenses 3 (48 MP + 8 MP + 13 MP) 4 (48 MP + 12 MP + 5 MP + 5 MP)
Wide (main) lens - 48 MP
- Aperture: f/1.8
- Focal length: 26 mm
- Pixel size: 0.8 micron
- Sensor: 1/2.25", Sony IMX582 Exmor RS (BSI CMOS)
- Phase autofocus
- 48 MP
- Aperture: f/2.0
- Focal length: 26 mm
- Pixel size: 0.8 micron
- Sensor: 1/2", Samsung S5KGM2 (ISOCELL CMOS)
- Phase autofocus
Telephoto lens - 8 MP
- Aperture: f/2.4
- Focal length: 53 mm
- Pixel size: 1.12 micron
- Sensor: 1/4", Omnivision OV8865 (BSI CMOS)
- Phase autofocus
-
Ultra-wide lens - 13 MP
- Aperture: f/2.4
- Focal length: 12 mm
- Pixel size: 1.12 micron
- Sensor: 1/3.1", Samsung S5K3L6 (ISOCELL CMOS)
- 12 MP
- Aperture: f/2.2
- Focal length: 13 mm
- Pixel size: 1.12 micron
Macro lens - - 5 MP
- Aperture: f/2.4
- Focal length: 40 mm
- Pixel size: 1.12 micron
Depth lens - - 5 MP
- Aperture: f/2.2
- Pixel size: 1.12 micron
- Sensor: 1/5.0" (CMOS)
Camera features - Bokeh mode
- Pro mode
- Bokeh mode
- Pro mode
Selfie camera
Megapixels 20 megapixels 32 megapixels
Image resolution 5184 x 3880 6560 x 4928
Aperture f/2.2 f/2.2
Focal length 18 mm 26 mm
Pixel size 0.8 microns 0.8 microns
Sensor type CMOS ISOCELL CMOS
Sensor size 1/3.4" 1/2.8"
Video resolution 1080p (Full HD) при 30 FPS 2160p (4K) при 30 FPS

Connectivity

Wi-Fi standard Wi-Fi 5 (802.11 b/g/n/ac) Wi-Fi 5 (802.11 b/g/n/ac)
Wi-Fi features - Dual Band
- Wi-Fi Direct
- Wi-Fi Hotspot
- Wi-Fi Display
- Dual Band
- Wi-Fi Direct
- Wi-Fi Hotspot
- Wi-Fi Display
Bluetooth version 5 5
Bluetooth features LE, A2DP PBAP/PAB, PAN, OPP, MAP, HSP, HID, HFP, DIP, AVRCP, A2DP
USB type USB Type-C USB Type-C
USB version 2 2
USB features - Charging
- USB-Storage mode
- USB-Host mode
- OTG
- Charging
- USB-Storage mode
- OTG
GPS GPS, GLONASS, Beidou, Galileo GPS, GLONASS, Beidou, Galileo
NFC* Yes Yes
Infrared port No No
Network
Number of SIM* 2 2
Type of SIM card Nano Nano
Multi SIM mode Standby Standby
eSIM support* No No
Hybrid slot No No
LTE Cat* 15 12
5G support No No

Sound

Speakers Mono Mono
Headphone audio jack Yes Yes
FM radio No Yes
Dolby Atmos No Yes
Speakers test
Max. loudness
81.2 dB
81.7 dB

Other

Category Mid-range Mid-range
Announced May 2019 December 2019
Release date July 2019 December 2019
Launch price ~ 250 USD ~ 250 USD
SAR (head) - 0.596 W/kg
SAR (body) - 1.45 W/kg
Sensors - Proximity sensor
- Gyroscope
- Accelerometer
- Ambient light sensor
- Compass
- Fingerprint
- Proximity sensor
- Gyroscope
- Accelerometer
- Ambient light sensor
- Compass
- Fingerprint
*Disclaimer! NFC, GSM network support, and some other specs can be different depending on the country.

Conclusion

If the performance and battery life are more important to you, then choose the Xiaomi Redmi K20. But if the software, camera, and sound are more of a priority – go for the Samsung Galaxy A51.

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