Phone Comparisons: ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra

AH ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra comparison 1

Both ASUS and Samsung released really compelling flagships this year, though they’re quite different in comparison. In this article, we’ll compare those two phones, the ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra. Saying that these two phones are not similar is an understatement, that’s for sure. The main difference is immediately noticeable, as they both look different, and are different in regards to the size.

In this article, we’ll compare the two phones across a number of categories, as per usual. We’ll start things off by comparing their specifications, and will then move to the design, display, performance, and several other categories. These two phones do differ quite a bit in all of these aspects, and even in their price tag. The ZenFone 8 is a considerably more affordable phone, and that’s definitely something to note.


ASUS ZenFone 8Samsung Galaxy S21 Ultra
Screen size5.9-inch fullHD+ Super AMOLED flat display (120Hz refresh rate)6.8-inch WQHD+ Dynamic AMOLED 2X display (120Hz adaptive refresh rate)
Screen resolution2400 x 10803200 x 1440
SoCQualcomm Snapdragon 888Qualcomm Snapdragon 888 / Samsung Exynos 2100
Storage128GB/256GB (UFS 3.1); non-expandable128GB/256GB, non-expandable (expandable in some countries)
Rear cameras64MP (f/1.8 aperture, 0.8um pixel size, 26mm lens, PDAF, OIS)
12MP (ultra-wide, f/2.2 aperture, 112-degree FoV, 14mm lens, 1.4um pixel size, dual pixel PDAF)
108MP (f/1.8 aperture, OIS, 0.8um pixel size. Produces 12MP images with 2.4um pixel size)
12MP (ultrawide, Dual Pixel AF, 120-degree FoV, f/2.2 aperture, 1.4um pixel size)
10MP (telephoto, Dual Pixel AF, OIS, f/2.4 aperture, 1.22um pixel size, optical zoom 3x)
10MP (telephoto, Dual Pixel AF, OIS, f/4.9 aperture, 1.22um pixel size, 10x optical zoom, 100x Space Zoom)
Front cameras12MP (f/2.5 aperture, 28mm lens, 1.22um pixel size, dual pixel PDAF)40MP (f/2.2 aperture, 80-degree FoV, 0.7um pixel size, PDAF)
Battery4,000mAh, non-removable, 30W wired charging, reverse wired charging5,000mAh, non-removable, fast battery charging (USB PD 3.0), Fast Wireless Charging 2.0, Wireless PowerShare
Dimensions148 x 68.5 x 8.9mm165 x 75.6 x 8.9 mm
Weight169 grams229 grams
Connectivity5G, LTE, NFC, Bluetooth 5.2, Wi-Fi, USB Type-C5G, LTE, NFC, Bluetooth 5.2, Wi-Fi, USB Type-C
SecurityIn-display fingerprint scanner (optical)In-display fingerprint scanner (ultrasonic)
OSAndroid 11
ZenUI 8
Android 11
One UI 3.0
Price€599 / €669 / €799$1,199.99

ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra: Design

Both of these phones are made out of metal and glass, but they both look different, and feel different in the hand. The ZenFone 8 is considered to be a compact smartphone, while the Galaxy S21 Ultra is the complete opposite of that. The ZenFone 8 is a lot shorter, and narrower than the Galaxy S21 Ultra. The two phones are equally thick, though, not counting their camera bumps. The Galaxy S21 Ultra is thicker if you take that into consideration.


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The Galaxy S21 Ultra is also a lot heavier. It weighs 227 grams compared to 169 grams of the ZenFone 8. Both phones have a display camera hole, though it’s placed in a different spot. Bezels are thin on both, while the ZenFone 8 has a flat display, unlike the Galaxy S21 Ultra, which sports a curved panel. Their rear cameras are located in the top-left corner, but those setups look a lot different. The ZenFone 8 includes two cameras there, while the Galaxy S21 Ultra has four.

The ZenFone 8 can be used with one hand rather comfortably, while that’s not the case with the Galaxy S21 Ultra, not at all. That device is not only too heavy for something like that, but it’s also too big. That’s what most people seem to prefer, though, but it’s worth noting that the S21 Ultra is a two-hand phone. Both devices are very slippery, and both are really well-built. They do feel like premium phones. The Galaxy S21 Ultra looks more premium, though, the ZenFone 8’s design is a bit understated. These two phones aim at completely different types of consumers, so the first thing you need to decide whether you want a compact, or a huge phone. From there you can compare other design aspects.


ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra: Display

The ASUS ZenFone 8 features a 5.9-inch fullHD+ (2400 x 1080) Super AMOLED display. That display offers a 120Hz refresh rate, and gets quite bright at 1,100 nits peak brightness. It does support HDR10+ content, and it’s a flat panel. The ZenFone 8’s display is protected by the Gorilla Glass Victus, the latest display protection Corning has to offer. This display is not small, and yet it’s considerably smaller than what the Galaxy S21 Ultra has to offer.

The Galaxy S21 Ultra sports a 6.8-inch QHD+ (3200 x 1440) Dynamic AMOLED 2X display. That is a 120Hz display with an adaptive refresh rate, in other words, we’re looking at an LTPO panel here. That display is curved, and it does support HDR10+ content. It also gets quite bright at 1,500 nits peak brightness, it’s actually one of the best, if not the best QHD+ panel in the market. It is also protected by the Gorilla Glass Victus, just like the ZenFone 8’s display.

Both devices have really good displays, but the Galaxy S21 Ultra’s does have an advantage. It has a more modern display with an adaptive refresh rate, which also gets quite a bit brighter. It’s also sharper than the ZenFone 8’s. That difference in sharpness is not something you’ll notice, though, well, at least the vast majority of you won’t. The ZenFone 8’s display is more than sharp enough. Both panels have really good viewing angles, and punchy colors, while blacks are deep, as you’d expect out of OLED displays.


ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra: Performance

Spoiler alert! In regards to general performance, both of these devices are fantastic. That’s not exactly surprising considering the specs that are included here. Both phones are fueled by the Snapdragon 888 SoC (the European and Indian variants of the Galaxy S21 Ultra come with an Exynos SoC, though), and include modern RAM and flash storage modules. They also come with the latest version of Android available, with proprietary skins from two OEMs.

When it comes to regular tasks, such as opening / closing apps, multitasking, taking pictures and videos… they’re both excellent, to say the least. They do the job fast, and with included animations, everything looks quite nice as well. Even when it comes to some more demanding tasks such as video processing, or something of the sort, they’re both excelling. The Snapdragon 888 really does come to shine on both phones.

Now, some of you are probably wondering about gaming. Well, you’ll be glad to know that they’re great in that regard as well. The ZenFone 8 even comes with some software from ASUS’ ROG Phone series. Both phones perform great, no matter what game you play on them. They can handle the most graphically intensive titles from the Play Store, without a problem. That is to be expected out of flagship phones, and these two certainly deliver. We did not notice any notable slowdowns in performance, not at all.


ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra: Battery

The ASUS ZenFone 8 comes with a 4,000mAh battery, while the Galaxy S21 Ultra has a 5,000mAh battery pack. The ZenFone 8 does have a lower-res display, and a smaller panel at that. Both phones offer really good battery life, though the Galaxy S21 Ultra has an edge in this regard. The Galaxy S21 Ultra will definitely run longer before it runs out of juice, in comparison with the ZenFone 8.

The Galaxy S21 Ultra was able to cross the 7-hour mark in our testing, a number of times. Your numbers will be different, of course, depending on your usage. Do note that we’re not really gamers, so that is not taken into account. In most cases, though, it was able to get to around 6.5 hours of screen on time. The ZenFone 8 operated around the 5.5-6 hours of screen on time mark. That is more than respectable for a device of its caliber and size.

Those numbers were not constant, of course. They changed from one day to the next, depending on our usage. You may get considerably different numbers in general. If you’re a gamer, do expect those numbers to be considerably lower, nothing drains battery like gaming, especially if you’re playing graphically intensive tasks. One thing is for sure, though, both phones offer really good battery life.


Both of them also support fast charging. The ASUS ZenFone 8 offers 30W fast wired charging, along with reverse charging. The Galaxy S21 Ultra, on the other hand, supports 25W fast wired charging, 15W wireless charging, and 5W reverse wireless charging. So, the ZenFone 8 offers faster charging in general, but it doesn’t offer wireless charging at all. So, if that’s something you need, the Galaxy S21 Ultra is the only option.

ASUS ZenFone 8 vs Samsung Galaxy S21 Ultra: Cameras

The ZenFone 8 has three cameras overall, two on the back, one on the front. The Galaxy S21 Ultra sports four cameras on the back, and one on the front. Both phones are really compelling in the camera department. Before we get down to details, it’s worth noting that the ZenFone 8 is a major improvement over the ZenFone 7 series. It has the same main sensor as the ZenFone 7, but the difference when it comes to actual performance is staggering.

Samsung Galaxy S21 Ultra AH 11


Both phones perform great in good lighting. Both of them capture really sharp images, with really good dynamic range, and colors. Those images also end up being plenty sharp. The images from the Galaxy S21 Ultra do tend to be a bit more saturated, and they do look more pleasant in a way. Their ultrawide cameras also do a great job, and the Galaxy S21 Ultra can also capture objects that are far away thanks to its periscope camera.

When the light goes away, you’d be surprised how well the ZenFone 8 can keep up the pace with the Galaxy S21 Ultra. The phone’s camera system allows for plenty of light to enter the scene, and it does a good job balancing images. You can get a lot of detail in such scenes. We would say that the Galaxy S21 Ultra does pull ahead a bit, but the ZenFone 8 is not far behind. You can even capture great-looking moon shots with the Galaxy S21 Ultra.


In regards to audio, both phones have a lot to offer. Both of these devices come with stereo speakers, which are really good. The ZenFone 8 can compete in regards to speaker performance despite its size. ASUS really did a great job with its speakers. The Galaxy S21 Ultra’s audio is tuned by AKG. Both provide excellent, deep sound, with almost no distortion. The sound output from their speakers is also quite loud, but not tinny, not at all.


The ASUS ZenFone 8 even has a 3.5mm headphone jack, if you’d like to plug in a pair of headphones. If you plug in a good pair of headphones, you’ll get really good sound output in return. In the case of the Galaxy S21 Ultra, you can opt for a dongle, Type-C earphones, or Bluetooth. Regardless of the way you connect your headphones, the Galaxy S21 Ultra will provide really good sound as well. They’re both really compelling when it comes to audio.