Samsung Galaxy M31 review: Best-in-class battery life

The longest-lasting battery we’ve ever seen, along with an exceptional display, make the M31 a bargain

IT Pro Verdict


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    Phenomenal battery life

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    Great cameras for the price

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    High-quality display


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    Exclusive to Amazon

If there’s one area of smartphone technology that hasn’t improved much in recent years, it’s battery life. Readers with long memories will recall the Lenovo P2 from 2016, which kept going for 29 hours in our video-rundown test – only to be mysteriously pulled from UK shop shelves a few months after release. We haven’t seen anything that comes close since.

Those who value battery life over glitz finally have hope, though. Samsung’s Galaxy M31 packs a gigantic 6,000mAh battery, which is 900mAh bigger than the Lenovo P2’s. And we won’t keep you in suspense: this larger battery meant the Galaxy lasted for 30hrs 20mins in our video-rundown test, beating the P2 by 90 minutes. Translated into real-world terms, that means you should hit two days of use on a single charge – perhaps even three.

What you won’t get is chart-topping speed, with Samsung’s Exynos 9611 chipset in charge. This features a mid-range processor, and it’s helped by a generous 6GB of RAM, but apps don’t leap into action with the same speed as on a top-tier smartphone – for example, Geekbench 5 returned scores of 264 and 1,219 in the single-core and multicore tests, which looks slow compared to the 311 and 1,402 of the £100 Nokia 5.3.

It’s a similar story for graphics, with an average frame rate of 24fps in the GFXBench Manhattan 3 test to the 44fps of Lenovo’s budget Moto 5G Plus. On a more positive note, at least there’s room to install plenty of apps: the 64GB of storage can be expanded by up to 1TB via the microSD slot.

The M31 includes a 6.4in Super AMOLED display with a 1,080 x 2,340 resolution and pin-sharp pixel density of 403ppi. We measured brightness peaking at 568cd/m2 in automatic mode, promising readability in even the sunniest climes, and the phone’s “Natural” colour profile is great if you’re looking for colour accuracy. It covered 99.7% of the sRGB colour space, with a total volume of 104% and an average Delta E of 1.94. Thanks to that AMOLED panel, the contrast is effectively perfect, meaning images have real presence and viewing angles are excellent. In short, this is a brilliant screen for the price.

The AMOLED display also compensates for what, if we’re being charitable, can be described as a “functional” design. The prominent black bezels give the M31 a chunky look that accentuates this phone’s 8.9mm thickness – the obvious drawback to including such a large battery. Nor are we a fan of the review sample’s black plastic rear, although it turned out that our fingerprints loved it. Still, it’s also available in blue and red, which should make such fingerprints less obvious.

One neat piece of design is the positioning of the selfie camera in a semi-circular notch at the top of the screen, and the display itself is protected with a layer of Gorilla Glass. We also like the sensibly positioned oval fingerprint reader on the back of the phone and the 3.5mm headphone jack. Plus the phone supports contactless payments via NFC and can be unlocked via facial recognition. Unfortunately, there’s no official IP-rating for dust or water protection and it doesn’t support wireless charging.

Finally, we come to the four cameras. The main 64-megapixel (f/1.8) unit is joined by an 8-megapixel (f/2.2) ultra-wide lens, 5-megapixel (f/2.4) macro camera and a depth sensor. And they’re excellent for the price. No matter the lighting conditions, the Galaxy M31 captures pictures that are packed with intricate details, along with well-judged exposure and accurate colour rendition. There isn’t much visual noise, even indoors in low light.

The intuitive camera software makes it easy to access shooting modes such as hyper-lapse, 960fps slow-motion recording, night and macro settings, while the Galaxy’s “live focus” portrait mode is as great as ever, allowing you to adjust the level of background blur before or after you capture the image. Video recording is equally impressive: while you’re limited to 30fps, 4K and 1080p footage is crisp and detailed with solid image stabilisation.

There are cheaper, faster phones – such as the Nokia 5.3, for example. However, for £245, you’re buying a smartphone that’s fast enough for most people, with a great screen and an excellent suite of cameras. Couple that with staggering battery life, and the Samsung Galaxy M31 stands alone. It’s only a shame that it’s exclusive to Amazon in the UK.

Samsung Galaxy M31 specifications


Octa-core Samsung Exynos 9611 (4x2.3Ghz, 4x1.7GHz)



Screen size


Screen resolution

2,340 x 1,080

Pixel density


Screen type


Front camera

32MP (f/2.0)

Rear camera

64MP (f/1.8), 8MP (f/2.2) wide, 5MP (f/2.4) macro, 5MP (f/2.2) depth



Dust and water resistance


3.5mm headphone jack


Wireless charging


USB connection type


Storage options


Memory card slot (supplied)








Cellular data


Dual SIM

Yes (dedicated slot)

Dimensions (WDH)

159 x 75 x 8.9mm



Operating system

Android 10 (One UI 2.0)

Battery size