LG X400 (K121K) vs LG K51S (K510EMW)

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Side by side comparison between LG X400 vs LG K51S phones, differences, pros, cons and full specifications. What's the better?

7/8/2020 11:12 PM, updated: 8/6/2020 1:57 PM

Compare LG K51S X LG X400 (K121K) 06Points

Specifications Compare Models Pictures

5.3"
IPS

720x1280

13
MP

5mp

2GB
RAM

Octa-core

2800
mAh

(Removable)

17Points LG K51S (K510EMW) Compare LG X400 X

Specifications Compare Models Pictures

6.55"
IPS

720x1600

32
MP

13mp

3GB
RAM

Octa-core

4000
mAh

(Non removable)

What's the better phone? LG K51S (K510EMW)

The phonemore's choice is much more technical than personal. Therefore, you shouldn't only consider this. Our goal is to help you, but what's important to us may not be important to you. You decide which one is the best! Comment!

6 Advantages LG X400 (K121K)	vs	17 Advantages LG K51S (K510EMW)
+142 grams (4.97 ounces)37% Lighter	vs	194 grams (6.79 ounces)
+8 millimeters (0.31 inches)3% Thinner	vs	8.26 millimeters (0.33 inches)
+277 PPI3% Crisper display of text, images and videos because it has more pixels per inch (ppi)	vs	268 PPI
+Li-Ion: lithium-ion (Removable)Advantage Removable battery can be replaced easily	vs	LiPo: li-ion polymer (Non removable)
+FM (RDS)Advantage The radio lets you listen to your songs and sports in general	vs	Not supported
+Digital TVAdvantage Watch your favorite TV shows anywhere	vs	Not supported
1.5GHz 64bit Octa-core	vs	+2.3GHz 64bit Octa-core (12nm)80% More powerful processor, you can open your applications faster
2GB LPDDR3	vs	+3GB LPDDR350% More RAM memory. Typically more responsive and better for multitasking.
32GB (22GB available)	vs	+64GB (47GB available)114% More internal storage for applications and files
Until 256GB microSD, microSDXC	vs	+Until 1TB microSD, microSDXC3 times More external storage for files using memory cards
720x1280 pixels	vs	+720x1600 pixels25% Higher resolution screen
5.3"	vs	+6.55"24% Larger screen
(back) 13MP	vs	+(quad camera) 32MP + 5MP + 2MP + 2MP2 times Higher resolution main camera
HDR photo only main camera	vs	+HDR photo on both camerasAdvantage The HDR technology produced photos with more detail in dark areas
f/2.2 (aperture)	vs	+f/1.8 (aperture)22% Diaphragm opening (Aperture) of the camera which has the smallest F number takes photos with better light exposure.
(front) 5MP	vs	+(front) 13MP160% Higher resolution secondary camera to take pictures and selfies
Android 8.0 Oreo	vs	+Android 9.0 PieAdvantage Android 9.0 Pie is newer and safer
2800 mAh	vs	+4000 mAh43% Battery - higher amperage (mAh) allows more device usage time, but it also depends on the hardware and use
1 slot (Single-SIM) (dedicated slot)	vs	+2 slots (Dual-SIM) (dedicated slot)Advantage You can have more mobile carriers/operators on the same device.
Not supported	vs	+DLNAAdvantage With DLNA technology you can access and play media files on TV, tablet or DLNA compatible device.
4.2 + A2DP	vs	+5.0 + A2DP/LEAdvantage Bluetooth 5.0 + A2DP/LE is newer and faster
MicroUSB 2.0, USB OTG On-The-Go	vs	+Type-CAdvantage Reversible connector, you can stick in a USB-C cable any which way; either side is up.
Not supported	vs	+MIL-STD-810G military certifiedAdvantage Protection against water allows you talk to your friends in the rain, for example

24 Common items in both devices

Plastic body, glass front

TFT IPS LCD

16 million

LED flash

Only digital zoom

Autofocus / PDAF: phase detection autofocus

EIS: Digital stabilization

+17 specs and more in the table below

Check the comparison table below for more items that are not evaluated in comparison score above.

Highlight differences

📱 Model features
	LG X400 (K121K)	LG K51S (K510EMW)
Change model		Choose the model
Model	X400 (K121K)	K51S (K510EMW)
Other model names	KT LG X400, LGM-K121K, LGMK121K (Korea Telecom)	LG K51s LM-K510EMW, LMK510EMW (Dual-Sim + NFC)
Country or region available	South Korea	(Europe), (Global, International)
Brand	LG	LG
Release date	2/1/2017	4/1/2020
Depth	8 millimeters (0.31 inches)	8.26 millimeters (0.33 inches)
Size (width x height)	75.29 x 148.7 millimeters (2.96 x 5.85 in)	76.7 x 165.2 millimeters (3.02 x 6.5 in)
Weight	142 grams (4.97 ounces)	194 grams (6.79 ounces)
Build, materials	Plastic body, glass front	Plastic body, glass front
Protection against water and others	Not supported	MIL-STD-810G military certified: salt, dust, humidity, rain, vibration, solar radiation, transport and thermal shock resistant.
📲 Display
	LG X400 (K121K)	LG K51S (K510EMW)
Display type	TFT IPS LCD	TFT IPS LCD
Screen size	5.3" inches	6.55" inches
Screen-to-body ratio	~69.2% (screen-to-body ratio)	~81.7% (screen-to-body ratio)
Display resolution	720x1280 pixels	720x1600 pixels (20:9)
Touchscreen	Capacitive Multitouch	Capacitive Multitouch
Pixel density (dot pitch)	277 PPI	268 PPI
Colors	16 million	16 million
Scratch-resistant glass	Not supported	Not supported
Refresh rate	feature not registered	60Hz
Display features	feature not registered	400nits[typ]
🤖 Operating System
	LG X400 (K121K)	LG K51S (K510EMW)
System version	Android 7.0 Nougat	Android 9.0 Pie
Firmware update	Android 8.0 Oreo	feature not registered
User Interface	feature not registered	feature not registered
⚙️ Processor
	LG X400 (K121K)	LG K51S (K510EMW)
Chipset	64bit: MediaTek MT6750 (28nm)	64bit: MediaTek Helio P35 (MT6765) (12nm)
CPU	Octa-core, 2 processors: 4x 1.5GHz ARM Cortex-A53 (Quad-core) 4x 1GHz ARM Cortex-A53 (Quad-core)	Octa-core, 2 processors: 4x 2.3GHz ARM Cortex-A53 (Quad-core) 4x 1.8GHz ARM Cortex-A53 (Quad-core)
GPU graphical controller	ARM Mali-T860 MP2 520Mhz	PowerVR GE8320 MP2 (680MHz)
Performance (benchmark)	feature not registered	feature not registered
💽 Memory and storage
	LG X400 (K121K)	LG K51S (K510EMW)
RAM memory	2GB LPDDR3	3GB LPDDR3
Internal storage	32GB (22GB available)	64GB (47GB available) eMMC 5.1
External storage	Until 256GB microSD, microSDXC (dedicated slot)	Until 1TB microSD, microSDXC (dedicated slot)
📶 Mobile networks
	LG X400 (K121K)	LG K51S (K510EMW)
Dual-SIM	Not supported	Dual-SIM Standby - Call active on one sim card (dedicated slot)
SIM card	1 slot (Single-SIM) nano-SIM (4FF)	2 slots (Dual-SIM) nano-SIM (4FF)
Maximum Download / Upload	300/50 Mbps	300/50 Mbps
Network technology	2G, 3G, 4G	2G, 3G, 4G
Frequency, bands	Expand band details Collapse details
GSM MHz band	Tri-Band 900/1800/1900	Quad-Band 850/900/1800/1900
Primary 2G network	GSM 900/1800/1900	GSM 850/900/1800/1900
Primary 3G network	UMTS 2100	UMTS 850/900/1900/2100
Primary 4G network	LTE Cat6 850/900/1800/2100/2600 (Bands 1,3,5,7,8) VoLTE	LTE Cat6 (1, 3, 7, 8, 20) TD-LTE (38)
Primary 5G network	Not supported	Not supported
Primary data network	GPRS, EDGE, UMTS, HSDPA, HSUPA, HSPA+, LTE, LTE-A	GPRS, EDGE, UMTS, HSDPA, HSUPA, HSPA+, TD-LTE, LTE, LTE-A
Secondary 2G network	Not supported	GSM 850/900/1800/1900
Secondary 3G network	Not supported	Not supported
Secondary 4G network	Not supported	Not supported
Secondary data network	Not supported	GPRS, EDGE
📷 Camera
	LG X400 (K121K)	LG K51S (K510EMW)
Back camera (main camera)	13 megapixels	(quad camera) 32 megapixels 5MP ultrawide f/2.216mm1.12μm115° 2MP macro f/2.422mm1.75μm88.6° 2MP depth f/2.41.75μm
Main camera resolution	4160x3120 pixels	6528x4896 pixels
Video recording (primary)	Full HD (1920x1080) 30 fps	Full HD (1920x1080) 30 fps
Flash	LED flash	LED flash
Focal aperture	f/2.2 (aperture)	f/1.8 (aperture)
Focal length	feature not registered	24mm lens
Sensor size	1/3" inches	feature not registered
Pixel size	1.12µm pixel	0.8µm pixel
Autofocus	Autofocus	PDAF: phase detection autofocus
Touch focus	Supported	Supported
Image stabilization	EIS: Digital stabilization	EIS: Digital stabilization
Zoom	Only digital zoom	Only digital zoom
Face/smile detection	Face detection, Smile detection	Face detection, Smile detection
BSI sensor	Not supported	Not supported
HDR	HDR photo only main camera	HDR photo on both cameras
Camera extras	feature not registered	feature not registered
📸 Front camera
	LG X400 (K121K)	LG K51S (K510EMW)
Front camera (secondary)	5 megapixels	13 megapixels
Front camera resolution	2560x1920 pixels	4128x3096 pixels
Video recording (secondary)	Full HD (1920x1080)	Full HD (1920x1080)
Front flash	Not supported	Not supported
Focal aperture	f/2.4 (aperture)	f/2.0 (aperture)
Focal length	feature not registered	feature not registered
Sensor size	1/5" inches	feature not registered
Pixel size	1.12µm pixel	feature not registered
🔉 Sound and multimedia
	LG X400 (K121K)	LG K51S (K510EMW)
Loudspeaker	Supported	Supported
Active noise cancellation	2 microphones or more	2 microphones or more
Radio	FM (RDS)	Not supported
TV	Digital TV	Not supported
Video formats	MP4, H.264, H.263, XviD, MKV	MP4, H.265, H.264, H.263, XviD, MKV
Audio formats	MP3, WAV, WMA, eAAC+, FLAC	MP3, WAV, WMA, eAAC+, FLAC
🔌 Connectivity
	LG X400 (K121K)	LG K51S (K510EMW)
USB	MicroUSB 2.0, USB OTG On-The-Go	USB 2.0 Type-C, USB OTG On-The-Go
Audio output	3.5mm jack	3.5mm jack
TV output	Not supported	Not supported
Bluetooth	4.2 + A2DP	5.0 + A2DP/LE
WiFi	802.11 b/g/n [wifi4] (2.4GHz) WiFi Direct, hotspot	802.11 a/b/g/n [wifi4] (2.4GHz, 5GHz) WiFi Direct, hotspot
DLNA	Not supported	Supported
GPS	A-GPS, GeoTagging, GLONASS	A-GPS, GeoTagging
NFC	Supported	Supported
Infrared port	Not supported	Not supported
🧭 Sensors
	LG X400 (K121K)	LG K51S (K510EMW)
Sensors	Accelerometer Ambient light sensor Compass Fingerprint sensor (rear-mounted) Proximity sensor	Accelerometer Ambient light sensor Compass Fingerprint sensor (rear-mounted) Proximity sensor
Vibrating alert	Supported	Supported
🔋 Battery
	LG X400 (K121K)	LG K51S (K510EMW)
Battery type	Li-Ion: lithium-ion (Removable)	LiPo: li-ion polymer (Non removable)
Battery capacity	2800 mAh	4000 mAh
Charger, watts	Wired charging	10W (5V/2A) Wired charging
Inductive / wireless charging	feature not registered	Not supported
Talk time autonomy	9 hours	10.5 hours
Standby	390 hours (16.3 days)	370 hours (15.4 days)
➕ Other features
	LG X400 (K121K)	LG K51S (K510EMW)
Call control	Voice dialing, Voice recorder	Voice dialing, Voice recorder, Voice commands
Messaging	SMS (T9), MMS, E-mail, Push mail	SMS (T9), MMS, E-mail, Push mail
Hands-free calling	Supported	Supported
Video calling	Supported	Supported
Ringtones	Polyphonic and customized	Polyphonic and customized
Web browser	HTML, XHTML, HTML5	HTML, XHTML, HTML5
Antenna	Internal antenna	Internal antenna
Qwerty physical keyboard	Not supported	Not supported
Miscellaneous	• Colors: Black, Gold • 2.5D Arc Glass screen • LG UX 5.0 • Wide-angle 120° front camera • KnockOn, Knock Code • DMB-TV (Korea)	• Colors: Titanium, Blue, Pink/Red • Silicone case included • Google Assistant (dedicated side button) • DTS:X 3D audio
☢️ Radiation rate
	LG X400 (K121K)	LG K51S (K510EMW)
SAR 1.6W/kg (USA, Mexico, etc.)	feature not registered	feature not registered
SAR 2W/kg (Europe, UK, etc.)	feature not registered	feature not registered