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Samsung Galaxy Watch (42mm SM-R815U) vs Xiaomi Amazfit T-Rex

Side by side comparison between Samsung Galaxy Watch vs Xiaomi Amazfit T-Rex smartwatches, differences, pros, cons and full specifications. What's the better?

Compare Xiaomi Amazfit T-Rex X Samsung Galaxy Watch (42mm SM-R815U) 13Points





(Non removable)






(Non removable)

What's the better smartwatch? Samsung Galaxy Watch (42mm SM-R815U)

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!

Galaxy Watch (42mm SM-R815U)} 13 Advantages Samsung Galaxy Watch (42mm SM-R815U) vs Amazfit T-Rex} 6 Advantages Xiaomi Amazfit T-Rex
+1.5GB LPDDR32 times
More RAM memory. Typically more responsive and better for multitasking.
vs512MB LPDDR3
+49 grams (1.72 ounces)18%
vs58 grams (2.03 ounces)
+12.7 millimeters (0.5 inches)6%
vs13.5 millimeters (0.53 inches)
+Stainless steel body, glass frontAdvantage
More resistant material
vsPlastic body, glass front
+Super AMOLEDAdvantage
Super AMOLED display is brighter and more vivid
+424 PPI8%
Crisper display of text, images and videos because it has more pixels per inch (ppi)
vs392 PPI
+1500 apps149 times
More apps available to download and use
vs10 apps
+4G LTEAdvantage
The 4G LTE network is newer and faster
vsNot supported
+(4G LTE) 10 MbpsAdvantage
Faster for surfing the internet and download files
vs(Not supported)
Sensors help you use the device
vsNot supported
Sensors help you use the device
vsNot supported
+802.11 b/g/n [wifi4]Advantage
WiFi 802.11 b/g/n [wifi4] is newer and faster
vsNot supported
NFC allows you to make payments by approach quickly and securely
vsNot supported
4GB (1.5GB available)vs+4GB (2GB available)33%
More internal storage for applications and files
Larger screen
Not supportedvs+CompassAdvantage
Sensors help you use the device
Not supportedvs+SpO2Advantage
Sensors help you use the device
270 mAhvs+390 mAh44%
Battery - higher amperage (mAh) allows more device usage time, but it also depends on the hardware and use
4.2 + A2DPvs+5.0 + A2DP/LEAdvantage
Bluetooth 5.0 + A2DP/LE is newer and faster

15 Common items in both devices
16 million
360x360 pixels
Ambient light sensor
+8 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 Clear highlight

📱 Model features

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
ModelGalaxy Watch (42mm SM-R815U)Amazfit T-Rex
Other model namesGalaxy Watch 42mm (4G LTE) SM-R815UZDAXAR, Samsung GalileoMi Amazfit TRex
Country or region availableUSA
(Global, International)
(Global, International)
Release date8/1/20181/9/2020, Announced: 1/1/2020
Depth12.7 millimeters (0.5 inches)13.5 millimeters (0.53 inches)
Size (width x height)41.9 x 45.7 millimeters (1.65 x 1.8 in)47.47 x 47.47 millimeters (1.87 x 1.87 in)
Weight49 grams (1.72 ounces)58 grams (2.03 ounces)
Build, materialsStainless steel body, glass frontPlastic body, glass front
Protection against water and others5 ATM: 50 meters waterproof.
MIL-STD-810G military certified: salt, dust, humidity, rain, vibration, solar radiation, transport and thermal shock resistant.
5 ATM: 50 meters waterproof

📲 Display

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Display typeSuper AMOLEDAMOLED
Screen size1.2" inches1.3" inches
Screen-to-body ratio~24.3% (screen-to-body ratio)~24.2% (screen-to-body ratio)
Display resolution360x360 pixels (1:1)360x360 pixels
TouchscreenCapacitive MultitouchCapacitive Multitouch
Pixel density (dot pitch)424 PPI392 PPI
Colors16 million16 million
Scratch-resistant glassGorilla Glass DX+Gorilla Glass 3
Refresh ratefeature not registered60Hz
Display featuresNot supportedNot supported

🤖 Operating System

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
System versionTizen 4.0Proprietary OS
Firmware updatefeature not registeredfeature not registered
User Interfacefeature not registeredRTOS

⚙️ Processor

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Chipset64bit: Samsung Exynos 9 Dual 9110 (10nm)32bit
CPUDual-core, 1 processor:
2x 1.15GHz ARM Cortex-A53 (Dual-core)
Single-core, 1 processor:
GPU graphical controllerARM Mali-T720 MP1feature not registered
Performance (benchmark)feature not registeredfeature not registered

💽 Memory and storage

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
RAM memory1.5GB LPDDR3512MB LPDDR3
Internal storage4GB (1.5GB available)
4GB (2GB available)
External storageNot supportedNot supported

📶 Mobile networks

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Dual-SIMNot supportedNot supported
SIM card1 slot (Single-SIM)
e-SIM (Eletronic)
Not supported
Maximum Download / Upload10 Mbpsfeature not registered
Network technology3G, 4Gfeature not registered
Frequency, bands Expand band details Collapse details
GSM MHz bandNot supportedNot supported
Primary 2G networkNot supportedNot supported
Primary 3G networkUMTS 850/1700/1900Not supported
Primary 4G networkLTE (Bands 2,4,5,12,13,25,26,66)Not supported
Primary 5G networkNot supportedNot supported
Primary data networkUMTS, HSDPA, HSUPA, HSPA+, LTENot supported
Secondary 2G networkNot supportedNot supported
Secondary 3G networkNot supportedNot supported
Secondary 4G networkNot supportedNot supported
Secondary data networkNot supportedNot supported

📷 Camera

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Back camera (main camera)Not supportedNot supported
Main camera resolutionNot supportedNot supported
Video recording (primary)Not supportedNot supported
FlashNot supportedNot supported
Focal aperturefeature not registeredfeature not registered
Focal lengthfeature not registeredfeature not registered
Sensor sizefeature not registeredfeature not registered
Pixel sizefeature not registeredfeature not registered
AutofocusNot supportedNot supported
Touch focusNot supportedNot supported
Image stabilizationNot supportedNot supported
ZoomNot supportedNot supported
Face/smile detectionNot supportedNot supported
BSI sensorNot supportedNot supported
HDRNot supportedNot supported
Camera extrasfeature not registeredfeature not registered

📸 Front camera

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Front camera (secondary)Not supportedNot supported
Front camera resolutionNot supportedNot supported
Video recording (secondary)Not supportedNot supported
Front flashNot supportedNot supported
Focal aperturefeature not registeredfeature not registered
Focal lengthfeature not registeredfeature not registered
Sensor sizefeature not registeredfeature not registered
Pixel sizefeature not registeredfeature not registered

🔉 Sound and multimedia

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
LoudspeakerSupportedfeature not registered
Active noise cancellationNot supportedNot supported
RadioNot supportedNot supported
TVNot supportedNot supported
Video formatsMP4feature not registered
Audio formatsMP3, WAV, WMA, OGG, eAAC+feature not registered

🔌 Connectivity

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
USBNot supportedNot supported
Audio outputNot supportedNot supported
TV outputNot supportedNot supported
Bluetooth4.2 + A2DP5.0 + A2DP/LE
WiFi802.11 b/g/n [wifi4] (2.4GHz)Not supported
DLNANot supportedNot supported
NFCSupportedNot supported
Infrared portNot supportedNot supported

🧭 Sensors

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Ambient light sensor
Heart rate
Ambient light sensor
Heart rate
Vibrating alertSupportedSupported

🔋 Battery

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Battery typeLi-Ion: lithium-ion (Non removable)LiPo: li-ion polymer (Non removable)
Battery capacity270 mAh390 mAh
Charger, watts3.5W (5V/0.7A) Wired chargingWired charging
Inductive / wireless chargingQi wireless chargingMagnetic charging (dock)
Talk time autonomyfeature not registered20 hours
Standby72 hours (3 days)480 hours (20 days)

➕ Other features

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
Call controlVoice dialing, Voice recorder, Voice commandsNot supported
MessagingSMS (T9), MMS, E-mail, Push mailSMS (T9), E-mail
Hands-free callingSupportedNot supported
Video callingNot supportedNot supported
RingtonesPolyphonic and customizedfeature not registered
Web browserNot supportedNot supported
AntennaInternal antennafeature not registered
Qwerty physical keyboardNot supportedNot supported
Miscellaneous• Colors: Midnight Black, Rose Gold
• Straps: Black, Grey, Red, Yellow, Purple, Pink, Brown
• Compatible with standard 20mm straps
• Always-on display
• Rotating bezel
• Samsung Pay
• Compatible with Sprint, T-Mobile and Verizon carriers
• Colors: Black, Gray, Camouflage, Army green, Khaki
• Watch band: 22mm
• BioTracker PPG
• 14 sports mode
• AppZepp app
• Compatible with Android 5.0/iOS 10 and above

☢️ Radiation rate

Galaxy Watch (42mm SM-R815U)Amazfit T-Rex
SAR 1.6W/kg (USA, Mexico, etc.)0.961W/kg (head), 1.786W/kg (body)feature not registered
SAR 2W/kg (Europe, UK, etc.)feature not registeredfeature not registered

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