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Samsung Galaxy M31s review: Undercutting the Galaxy A51, and how


Last updated: September 20th, 2021 at 15:08 UTC+02:00

Samsung’s Galaxy M lineup of phones is constantly changing and improving, more so than any other smartphone lineup in the company’s repertoire. And it makes sense: The M series was designed to take on Samsung’s Chinese rivals in India’s budget segment, and like those Chinese rivals, the Korean giant has to keep iterating and bringing out new phones to stay relevant.

The latest phone Samsung has to offer in the M series is the Galaxy M31s, which is the costliest phone in the lineup yet. But it also has a couple of attractive new features to justify the higher price, such as an Infinity-O display and 25W super fast charging, and that’s in addition to everything that made the Galaxy M31’s spec sheet so good, like a 64MP quad-camera setup and a 6,000 mAh battery.

In fact, the Galaxy M31s makes the Galaxy A51 wholly unnecessary in the Indian market, and it also makes phones like the Galaxy A21s look horribly overpriced. But do the upgraded features over the Galaxy M31 make for a better user experience, one that you won’t regret spending for? Let’s dive right into this Galaxy M31s review to find the answer.

Before I begin, I should point out that this review is only going to focus on what’s new and different on the Galaxy M31s. For everything else, such as performance and camera quality, don’t forget to check out our Galaxy M31 review.

Design and display

Galaxy M31s review

The Galaxy M31s has the same ‘glasstic’ construction as its siblings, but Samsung has opted for a gradient finish at the back this time around to make the phone stand out. The Mirage Black version we received for review looks great, and thanks to the heft that you expect from phones with 6,000 mAh batteries, the plastic doesn’t feel cheap in the hand. The M31s basically uses the same build materials as and looks similar to A series phones like the Galaxy A51, which isn’t a bad thing unless you want all your phones to have glass on the back.

Also similar between the Galaxy M31s and A51 is the 6.5-inch Infinity-O Super AMOLED display. Except for the position of the front camera notch, not much has changed in practical terms. You still get an amazing viewing experience thanks to the deep blacks, vivid colors, and wide viewing angles, along with somewhat higher maximum brightness from what I could notice. However, the bezels are still pretty big, especially at the bottom, and hopefully that’s something Samsung will tackle with future entries in its budget and lower mid-range lineups.

Galaxy M31s review

In addition to the Infinity-O display, a side-mounted fingerprint sensor has also made its way to the M series for the first time. I’m glad Samsung didn’t put an in-display fingerprint scanner on the M31s, as those are nowhere near as fast, accurate, and reliable as physical scanners. And with the fingerprint reader mounted in the power button, it’s more convenient to use than rear-facing fingerprint sensors. This is the perfect implementation in my books, and you’ll feel the same if you decide to purchase this phone.


Galaxy M31s review

While the M31s has a newer 64MP main camera sensor than the M31, I didn’t really see any meaningful difference in picture quality, so I’m going to suggest looking at our M31 review to find out what you can expect from photos you shoot on this phone. However, there are two features that separate the M31s from the pack, and that’s Single Take mode and a full-fledged Pro mode

Single Take is a One UI 2.1 feature and so it should make its way to the Galaxy M31 and Galaxy M21 with the Android 11 update, but right now, it’s only available on the M31s and, in my opinion, the most thoughtful camera mode Samsung has conceived in recent memory. When you press the shutter button in Single Take mode, the camera takes a series of photos and videos, including photos with various filters and boomerang and hyperlapse videos.

It’s great for situations where you don’t want to choose between taking a photo and shooting a video, like a birthday celebration or when your pet is doing something cute. Surprisingly, the M31s is very quick at processing all the photos and videos it shoots in Single Take mode. I had expected that process to be slower because of the weaker processor, but it’s almost as quick as it is on Samsung’s flagship phones.

As far as Pro mode is concerned, the Galaxy M31s lets you control the camera’s shutter speed, which is something Samsung has only just started offering on its affordable phones. Basically, you can now take matters into your own hands if the automatic shooting mode doesn’t work for you. Having a full-fledged Pro mode is particularly useful for low-light shots. Night mode is great for automatically getting higher-quality nighttime photos, but by controlling the shutter speed and ISO values of the camera, you can get even better results.

Below is a side-by-side comparison of a scene I captured in Night mode (slide right) and by using Pro mode (slide left). I had to keep the phone down on a surface to make sure there’s no blur in the Pro mode photo, but I managed to get a picture with a little more light and a little less noise by using custom shutter speed and ISO values. It’s also worth noting that Night mode cuts off part of the frame, so that’s another reason to try Pro mode at nighttime so you can capture the full scene.


For ultra-wide photos, the M31s has a 12MP camera, which is the highest-resolution ultra-wide camera of any M series phone yet. The 12MP sensor enables slightly higher detail in ultra-wide shots compared to the 8MP sensor Samsung used previously, at least when you zoom in. However, the depth, macro, and selfie cameras remain the same as those on the M31, so once again I would suggest checking our review of that phone if you want all the details and some camera samples.

Battery life, charging

Galaxy M31s review

Battery life on the M31s is as amazing as it was on the M31 (nearly two days with light use and a full day with heavy use), but faster charging makes a world of difference. You no longer need to wait almost two hours and a half for the phone to attain full charge. That happens in a little less than 100 minutes now, and an hour of charging can comfortably get you through the entire workday thanks to the large battery capacity. In case you’re wondering, yes, you do get a 25W charger in the box.


The M31s runs Android 10 with One UI 2.1 out of the box. Well, it’s the Core version of One UI 2.1 so you miss out on some features, but the important ones, such as Quick Share and Music Share, are present, in addition to everything you get on the M31. Quick Share lets you quickly share files over Wi-Fi with other Galaxy phones running One UI 2.1, while Music Share enables your friends and family to play music on a Bluetooth audio device that’s connected to your phone, without having to connect to that Bluetooth device themselves.

Unfortunately, you still don’t get to use Samsung Pay despite paying a higher price tag, nor do you get Samsung Pay Mini. Samsung has also not removed the pesky notification that asks you to check out and install a few third-party apps – even if you don’t install any, you have to go through the process of viewing them before the notification goes away. Yes, it’s a good way for Samsung to make up for the tighter profit margins on its M series phones, but it’s not ideal at the M31s’ asking price.


I don’t understand what Samsung is doing in India right now. It’s got the Galaxy A series and the Galaxy M series competing with each other, and in every situation, it’s the latter that comes out on top. With the Galaxy M31s, Samsung is making the Galaxy A21s (review), Galaxy A31 (review), and Galaxy A51 (review) obsolete for Indian customers, at least if you want to get the most bang for buck.

The Galaxy M31 was already a fantastic value-for-money proposition, and the M31s makes things even better by offering support for 25W super fast charging to go along with the big battery, a versatile camera setup with the neat Single Take mode, and a side-mounted fingerprint scanner. The Infinity-O Super AMOLED display is also excellent, and while the camera quality tends to be not-so-great at night, you can now get around that by using the full-fledged Pro mode.

In short, if you have the budget, you can’t go wrong with the Galaxy M31s. Go buy it.


Galaxy M31s

What we like

  • Excellent Super AMOLED display
  • Good-looking design
  • Fantastic battery life, 25W super fast charging
  • Cameras perform well in daylight, 4K video recording support
  • Single Take and full-fledged Pro mode are useful additions to the camera app
  • Good performance in games and most day-to-day tasks
  • 128GB of expandable storage as standard

What we don't

  • Some stutter and lag in general navigation
  • Cameras don’t do great in low-light conditions
  • Barebones software package, no screen recorder, Samsung Pay, or Bixby
  • A faster processor would have been nice at this price point
Review Galaxy M31s
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