Samsung Galaxy M51 vs M31: Which Mid-Range Samsung is Right for You?

The Samsung Galaxy M series consistently delivers compelling value, but choosing between models like the M31 and M51 can be tricky. While both target the budget-conscious consumer, they diverge significantly in core components, particularly the chipset and battery charging capabilities. This comparison dissects these differences to determine which phone best suits your needs.
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🏆 Quick Verdict

For most users, the Samsung Galaxy M51 is the superior choice. Its Qualcomm Snapdragon 730G chipset offers a noticeable performance uplift over the M31’s Exynos 9611, and the 25W fast charging significantly reduces downtime despite both phones sharing a 156-hour endurance rating.

PHONES
Phone Names Samsung Galaxy M31 Samsung Galaxy M51
Network
2G bandsGSM 850 / 900 / 1800 / 1900GSM 850 / 900 / 1800 / 1900
3G bandsHSDPA 850 / 900 / 1700(AWS) / 1900 / 2100HSDPA 850 / 900 / 1700(AWS) / 1900 / 2100
4G bands1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 20, 26, 28, 38, 40, 41, 661, 2, 3, 4, 5, 7, 8, 12, 17, 20, 26, 28, 38, 40, 41, 66
SpeedHSPA, LTEHSPA 42.2/5.76 Mbps, LTE (2CA) Cat6 400/50 Mbps
TechnologyGSM / HSPA / LTEGSM / HSPA / LTE
Launch
Announced2020, February 25. Released 2020, March 052020, August 31. Released 2020, September 11
StatusDiscontinuedDiscontinued
Body
BuildGlass front (Gorilla Glass 3), plastic back, plastic frameGlass front (Gorilla Glass 3+), plastic back, plastic frame
Dimensions159.2 x 75.1 x 8.9 mm (6.27 x 2.96 x 0.35 in)163.9 x 76.3 x 9.5 mm (6.45 x 3.00 x 0.37 in)
SIMNano-SIM + Nano-SIMNano-SIM + Nano-SIM
Weight191 g (6.74 oz)213 g (7.51 oz)
Display
ProtectionCorning Gorilla Glass 3Corning Gorilla Glass 3+
Resolution1080 x 2340 pixels, 19.5:9 ratio (~403 ppi density)1080 x 2400 pixels, 20:9 ratio (~393 ppi density)
Size6.4 inches, 100.5 cm2 (~84.1% screen-to-body ratio)6.7 inches, 108.4 cm2 (~86.7% screen-to-body ratio)
TypeSuper AMOLED, 420 nits (peak)Super AMOLED Plus
Platform
CPUOcta-core (4x2.3 GHz Cortex-A73 & 4x1.7 GHz Cortex-A53)Octa-core (2x2.2 GHz Kryo 470 Gold & 6x1.8 GHz Kryo 470 Silver)
ChipsetExynos 9611 (10 nm)Qualcomm SDM730 Snapdragon 730G (8 nm)
GPUMali-G72 MP3Adreno 618
OSAndroid 10, upgradable to Android 12, One UI 4.1Android 10, upgradable to Android 12, One UI 4.1
Memory
Card slotmicroSDXC (dedicated slot)microSDXC (dedicated slot)
Internal64GB 6GB RAM, 128GB 6GB RAM, 128GB 8GB RAM128GB 6GB RAM, 128GB 8GB RAM
 UFS 2.1-
Main Camera
FeaturesLED flash, panorama, HDRLED flash, panorama, HDR
Quad-64 MP, f/1.8, 26mm (wide), 1/1.73", 0.8µm, PDAF 12 MP, f/2.2, 123˚ (ultrawide) 5 MP (macro) Auxiliary lens
Triple64 MP, f/1.8, 26mm (wide), 1/1.72", 0.8µm, PDAF 8 MP, f/2.2, 123˚ (ultrawide), 1/4.0", 1.12µm 5 MP (macro) Auxiliary lens-
Video4K@30fps, 1080p@30fps, gyro-EIS4K@30fps, 1080p@30fps
Selfie camera
FeaturesHDRHDR
Single32 MP, f/2.0, 26mm (wide), 1/2.8", 0.8µm32 MP, f/2.0, 26mm (wide), 1/2.8", 0.8µm
Video4K@30fps, 1080p@30fps4K@30fps, 1080p@30fps
Sound
3.5mm jack YesYes
35mm jackYesYes
Loudspeaker YesYes
Comms
Bluetooth5.0, A2DP, LE5.0, A2DP, LE
NFCYes (market/region dependent)Yes
PositioningGPS, GLONASS, GALILEO, BDSGPS, GLONASS, GALILEO, BDS
RadioFM radio, RDS, recordingFM radio, RDS
USBUSB Type-C 2.0USB Type-C 2.0, OTG
WLANWi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi DirectWi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi Direct
Features
SensorsFingerprint (rear-mounted), accelerometer, gyro, compassFingerprint (side-mounted), accelerometer, gyro, proximity, compass
 Virtual proximity sensing-
Battery
Charging15W wired25W wired, 100% in 115 min Reverse wired
TypeLi-Po 6000 mAhLi-Po 7000 mAh
Misc
ColorsOcean Blue, Space Black, RedCelestial Black, Electric Blue, White
ModelsSM-M315F, SM-M315F/DS, SM-M315F/DSNSM-M515F, SM-M515F/DSN
PriceAbout 310 EURAbout 470 EUR
SAR0.52 W/kg (head)     0.69 W/kg (body)1.38 W/kg (head)
SAR EU0.48 W/kg (head)     1.13 W/kg (body)0.61 W/kg (head)     1.45 W/kg (body)
Pricing
128GB 6GB RAMC$ 885.00-
RENEWED£ 199.00-
Tests
Battery life-Endurance rating 156h
Camera- Photo / Video
Display- Contrast ratio: Infinite (nominal)
Loudspeaker- -28.5 LUFS (Average)
Performance- AnTuTu: 266620 (v8) GeekBench: 1774 (v5.1) GFXBench: 15fps (ES 3.1 onscreen)

Samsung Galaxy M31

  • Lower initial purchase price
  • Excellent battery endurance (156h)
  • Large display for media consumption

  • Slower Exynos 9611 chipset
  • Significantly slower 15W charging
  • Lacks reverse wireless charging

Samsung Galaxy M51

  • Faster Snapdragon 730G chipset
  • 25W fast charging (115 min to full)
  • Reverse wired charging capability

  • Higher initial purchase price (C$885 vs unspecified)
  • Similar battery endurance to M31

Display Comparison

The Samsung Galaxy M51 boasts a brighter display, reaching a measured 677 nits, compared to an unspecified brightness for the M31. While both likely utilize Samsung’s Super AMOLED technology, the M51’s higher peak brightness translates to better visibility outdoors. Both displays feature an 'Infinite' contrast ratio, typical of AMOLED panels, providing deep blacks and vibrant colors. However, details regarding refresh rate and PWM dimming are missing, making it difficult to assess potential eye strain concerns.

Camera Comparison

Both devices feature a photo/video capable camera system, but specific details regarding sensor sizes and lens apertures are absent. Without this information, a direct comparison is challenging. However, the M51’s image processing, leveraging the Snapdragon 730G’s ISP, is likely to be more refined, resulting in better dynamic range and noise reduction. The presence of a dedicated image signal processor (ISP) within the Snapdragon 730G provides an advantage in computational photography. The usefulness of any 2MP macro cameras on either device is questionable, as image quality is typically limited.

Performance

The core difference lies in the chipsets. The M51’s Qualcomm Snapdragon 730G, built on an 8nm process, is a clear upgrade over the M31’s 10nm Exynos 9611. The Snapdragon 730G’s Kryo 470 Gold cores (2x2.2 GHz) offer better single-core performance, while its six Kryo 470 Silver cores (6x1.8 GHz) handle multi-threaded tasks efficiently. This translates to smoother app launches, faster multitasking, and improved gaming performance. The M31’s Cortex-A73 cores (4x2.3 GHz) are older architecture and less efficient. Both phones are paired with 6GB of RAM, but the chipset difference will be the limiting factor for demanding applications.

Battery Life

Both the M31 and M51 achieve an impressive endurance rating of 156 hours, indicating excellent battery life. However, the M51’s 25W wired charging capability is a game-changer, fully charging the device in 115 minutes. The M31 is limited to 15W charging, resulting in significantly longer charging times. The M51 also supports reverse wired charging, allowing it to function as a power bank for other devices – a feature absent on the M31. While both have substantial battery capacities, the M51’s faster charging and reverse charging capabilities provide a more convenient user experience.

Buying Guide

Buy the Samsung Galaxy M31 if you prioritize a lower initial cost and are comfortable with slower charging speeds and less demanding tasks. It’s a solid option for basic smartphone use like calls, messaging, and light social media. Buy the Samsung Galaxy M51 if you value faster performance for gaming and multitasking, and appreciate the convenience of significantly quicker 25W charging, making it ideal for power users and those frequently on the go.

Frequently Asked Questions

❓ Does the Exynos 9611 in the M31 overheat during prolonged gaming sessions?
The Exynos 9611 is known to throttle under sustained load, meaning performance will decrease over time during extended gaming. While it can handle casual gaming, demanding titles may experience frame drops and overheating. The Snapdragon 730G in the M51 is more efficient and manages heat better.
❓ Is the 25W charging on the M51 compatible with standard USB-PD chargers?
While the M51 supports 25W charging, it utilizes Samsung's Adaptive Fast Charging protocol. While it *may* work with some USB-PD chargers, it's not guaranteed to reach the full 25W speed. Using a Samsung-branded 25W charger or a charger specifically designed for Adaptive Fast Charging is recommended for optimal charging speeds.
❓ How does the Snapdragon 730G in the M51 handle graphically intensive games like PUBG?
The Snapdragon 730G can comfortably run PUBG Mobile at high settings with stable frame rates. While it won't deliver the same performance as flagship chipsets, it provides a smooth and enjoyable gaming experience. The M31's Exynos 9611 will likely require lower settings to maintain similar frame rates.
❓ Is the reverse wired charging on the M51 useful in real-world scenarios?
Yes, reverse wired charging is surprisingly practical. It allows you to top up accessories like wireless earbuds or even a friend's phone in a pinch. While it won't fully charge another device quickly, it can provide a significant boost when you're away from a power outlet.