Asus Zenfone 9 Review: A better small phone than the iPhone 13 Mini

Asus’ Zenfone series wasn’t always small. Just a couple of years ago, the Zenfone 7 and Zenfone 7 Pro came with the usual 6.7-inch screen that were and still are a dime a dozen in the Android space. But starting with last year’s Zenfone 8, Asus pivoted direction with one mandate: the phone must be small. The engineers and designers had hard numbers to aim for, in fact: the width of the device must be less than 70mm. The number, Asus reps say, is because it’s about the furthest the average human thumb can reach across horizontally. Asus succeeded in that goal, and the Zenfone 8 was a very easy one-hand phone, and perhaps due to utter lack of competition, it was named the best small Android phone by just about every tech publication.

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But other than being small, the Zenfone 8 didn’t have any other remarkable features. It ran on the same chip as every other Android flagship, had mediocre cameras, and perhaps most damningly, it had one of the plainest and most generic designs I’ve ever seen.

All that changes with the Zenfone 9: it’s got a visually striking design that looks and feels great, an improved main camera supported by a miniature gimbal stabilization system, a brand new Snapdragon flagship chip that may be making its debut in North America, and yes, Asus still managed to keep the phone small. With a starting price of $699, the Zenfone 9 is a no-brainer recommendation for not just people looking for a small phone, but those looking for a great value flagship.

And by the way, notice I didn’t take the easy way out and say the Zenfone 9 is for those looking for a “small Android phone.” No, I think this is the best small phone, period. Apple has probably already axed its Mini line, but if it were still making Mini iPhones, it should take some notes from Asus.

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Asus Zenfone 9: Pricing and Availability

The Asus Zenfone 9 will go on sale in many parts of the world, including the US, Canada, UK, Singapore, Hong Kong, and Taiwan soon. In the US, the Zenfone 9 has a suggested retail price of $699 for the base 8GB/128GB model, while that same model starts at €799 in Europe.

Asus Zenfone 9

Asus Zenfone 9

The Asus Zenfone 9 is a small phone that packs a powerful flagship chip and a gimbal camera system that works.

$649 at Amazon

Asus Zenfone 9: Specifications

Specification

Asus Zenfone 9

Build

• IP68 dust and water resistance
• Polycarbonate back
• Gorilla Glass Victus front

Dimensions & Weight

• 146.5 x 68.1 x 9.1 mm
• 169g

Display

• 5.9-inch Samsung AMOLED
• 120Hz
• 1080 x 2400
• 800 nits peak brightness

SoC

Qualcomm Snapdragon 8 Plus Gen 1

RAM & Storage

• 8GB LPDDR5 RAM + 256GB UFS 3.1 storage
• 8GB + 256GB
• 16GB + 256GB

Battery & Charging

• 4,300mAh
• 30W wired fast charging support

Security

Side-mounted fingerprint scanner

Rear Camera(s)

• Primary: 50MP Sony IMX766, f/1.9, supported by gimbal system
• Ultra-wide: 12MP IMX363, f/2.2

Front Camera(s)

12MP IMX663

Port(s)

USB Type-C

Audio

• Stereo speakers

Connectivity

• Dual 5G
• 4G LTE
• Wi-Fi 6
• Bluetooth 5.2
  • BLE Audio support
  • Snapdragon sound support
  • AAC/LDAC/LHDC/aptX Adaptive
• Multi-functional NFC

Software

ZenUI based on Android 12

Other Features

• Headphone jack
• 30W charger included

About this review: Asus provided my colleague Adam Conway and I with a Zenfone 9 each for testing. This review was written after nearly two weeks of testing the phone. Asus did not have any input in this review.

Asus Zenfone 9: Hardware and Design

• 5.9-inch screen makes for a very easy-to-use one-hand phone, yet it’s not too small like an iPhone 13 Mini screen
• A major aesthetic improvement over the Zenfone 8
• Really, really good battery life for a small phone

One complaint I often hear from phone fans is that mobile brands save the best hardware features for large phones, leaving the smaller phones in a lower tier. Well, Asus engineers made a good point during a recent media briefing: making a small flagship in 2022 is much more difficult than a decade ago because top mobile components have drastically increased in size. According to Asus, the Qualcomm Snapdragon 8 Plus Gen 1 chip powering the Zenfone 9 is 10% larger in size than last year’s Snapdragon 888; the Zenfone 9’s improved camera system is 40% larger than the Zenfone 8’s cameras; and the Zenfone 9’s battery and thermal system are also much larger than last year.

Despite that, Asus still managed to keep the Zenfone 9’s overall footprint roughly the same (and the weight exactly the same) as the Zenfone 8. Measuring 146.5 x 68.1 x 9.1 mm and weighing 169g, the Zenfone 9 is still a very small phone by 2022 standards. My thumb can indeed reach the other side of the screen easily, though it still needs to stretch a bit to reach the top corners. But that’s totally a non-issue, because Android’s UI, plus Asus’ software fine-tuning, means I never have to reach the very top of the screen to do anything. There’s no annoying “swipe from upper right corner” action that the iPhones make me do a dozen times a day. I’ll talk more about this later in the software section, but it’s absolutely baffling to me how one-hand unfriendly some other phone UIs are.

Asus engineers said two things helped them keep the Zenfone 9 the same size as the 8 despite having larger components: switching to a polycarbonate (aka plastic) back plate that is lighter than the glass back used last year, and the Zenfone 9 uses a boxier form instead of the curved, tapered sides and corners of last year. This effectively frees up enough space for Asus to cram components in without increasing the height and width of the phone.

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It’s small, not tiny, and that’s great news

In the big phone vs small phone debate, I am always in camp big phone. Sure, small phones are easier to hold and shove into pockets, but we live in an age when many (most?) of us stare at our phone screens more than any other screen. And whether it’s reading a press release, watching a TikTok video, or even framing a photo, content looks way better on an iPhone 13 Pro Max than on an iPhone 13 Mini. I will sacrifice a bit of hand comfort and pocket space for a more immersive screen that doesn’t require me to squint.

The Asus Zenfone 9 is small, the iPhone 13 Mini is tiny.

The Asus Zenfone 9’s 5.9-inch screen is about the perfect small phone size in 2022 — anything smaller is just too small

The Asus Zenfone 9’s 5.9-inch screen is about as small as I’m willing to go. Anything smaller, like the iPhone 13 Mini’s 5.4-inch display, just feels too cramped for modern apps, particularly social media, which are all about beautiful visuals. I think the Zenfone 9’s overall shape is about the perfect “small phone” size in 2022.

A plastic back that’s actually good

I am a fan of this polycarbonate back plate, which has a sandstone-like, grippy texture. The back side is entirely clean in three of four quadrants, with the upper left corner housing two large camera lenses and some text and odd arrow markings. I’m usually not a fan of random text and markings on phones, but they’re small enough here that I’m fine with it, and I like the strikingly large, symmetrical double camera rings. Unfortunately, my review unit is in perhaps the dullest color (black), but it’s still a major aesthetic improvement over last year’s bland, blah slab. I’d say my black model Zenfone 9 looks good, but the blue and red versions look great.

The aluminum chassis has flat sides but is not as hard-angled as an iPhone 12 or 13, the edges are slightly chamfered, so the corners do not dig into my palm. The metal railings house several interesting parts. The first is a touch-sensitive panel on the right side, right underneath the power button that doubles as a fingerprint scanner. This panel allows you to assign app launches or actions to a swipe. The second cool bit is the existence of a 3.5mm headphone jack. Personally, I have moved onto Bluetooth earphones long ago, but there are people out there who still lament the loss of this port, so Asus has them covered. Finally — and this last bit is just a superficial flourish — but the SIM tray cover curves along with the phone’s corner. It’s a nice little design touch that takes a bit more engineering work than most other SIM tray covers.

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Display

Technically speaking, going by spec sheet numbers, the Zenfone 9’s 5.9-inch 120Hz OLED panel isn’t at the level of other high-end flagship screens. The Zenfone 9 screen is not an LTPO panel, for example, so you must choose between 60Hz, 90Hz, or 120Hz refresh rate (or let the phone switch for you automatically); the resolution of 1080 x 2400 packs fewer pixels than WQHD+ screens, and the maximum brightness of 800 nits doesn’t get as bright as the Galaxy S22 Ultra or iPhone 13 Pro screen.

But you know what, this doesn’t really matter to 99% of people, including myself. Maybe XDA’s resident display expert Dylan Raga may say otherwise, but I don’t think most people can look at this panel and say “oh yeah this isn’t as great as the Galaxy S22 Ultra panel.” The screen is sharp enough, the colors pop enough, and the only time I found the maximum brightness lacking is when I’m out under harsh open sunlight. We must also remember the Zenfone 9 costs 30-40% cheaper than all the other phones I just mentioned. This screen is perfectly good for what it is.

SoC, memory, and other hardware bits

The Asus Zenfone 9 is powered by the Qualcomm Snapdragon 8 Plus Gen 1, making for one of the first phones to reach North America with this chipset. I’ve already tested a couple of devices with this chip, and the main takeaway is that it has noticeably better energy efficiency. This, coupled with the relatively larger 4,300 mAh battery makes for surprisingly good battery life for a small phone. In fact, the Zenfone 9 may have the best battery life of any small phone I’ve used in the last few years. Phones like the iPhone 13 Mini and Pixel 4a never could last a full day out for me, the Zenfone 9 can sometimes do it. I’ll elaborate on battery life more in the performance section. The battery can be charged at a maximum of 30W speeds (charger included) but there is no wireless charging.

The Zenfone 9 starts with 8GB LPDDR5 RAM and 128GB of UFS 3.1 storage, with the next option up doubling storage to 256GB. The highest model doubles the RAM too to 16GB. The lack of an in-between 12GB option is a bit odd. My review unit is the highest 16GB version, and performance has been fast and smooth. But I think the 8GB RAM model should perform just fine.

Other hardware bits range from good to great: there’s IP68 water-and-dust resistance; stereo speakers that sound good for a small phone (but definitely lacking in the oomph that a larger phone can pump out); and a decent haptic engine.

Asus Zenfone 9: Cameras

• 50MP main camera supported by a miniature gimbal system does indeed produce more stable videos
• Colors can be too contrasty at times
• The ultra-wide camera is just okay

The Zenfone 9’s dual-lens camera system comprises of a 50MP f/1.9 main (wide) camera and a 12MP ultra-wide camera. The main shooter uses a Sony IMX766 sensor, a widely used and proven sensor with a 1/1.57-inch image sensor. While the 1/1.57-inch is not going to impress a spoiled reviewer like me (because I’ve been using 1-inch sensors lately), it’s still a major size increase over last year’s Zenfone 8 or the iPhone 13 Mini’s image sensor.

But more interestingly, the main camera is supported by a miniature three-axis gimbal stabilization system that keeps the lens in a floating state. If you move the phone around, you can actually see the lens shift. This technology is not new, Vivo has been using it in its flagship phone for years, but this is the first time North American consumers will have access to this technology.

You can see the camera lens shift around as you move the phone.

Just like Vivo’s gimbal system, don’t expect Asus’ gimbal to perform miracles. It’s not going to entirely remove shakes and bobs the way a large size gimbal can do for real cameras. But this miniature gimbal does help stabilize more so than a typical OIS system. An Asus rep says the gimbal allows for an additional three-degree of movement in the the X- and Y-axis (the up and down movement), plus compensate for a bit of “yaw movement,” which is when the phone is wobbling left to right while facing the same direction. Traditional OIS systems do not compensate for yaw movements. I’ll let video samples do the talking, the below video clips show the Zenfone 9 stabilizing a yaw movement shake, followed by a bunch of handheld video samples shot in various lighting conditions, including on a rocky Hong Kong tram.

A few takeaways from the video samples, the gimbal does offset some of the shakes that came from jerking the phone’s yaw movement back and forth, and it does help produce incredibly smooth panning shots even when I was holding the phone with one hand. But walk and talk footage will still exhibit that up-and-down bobbing movement, particularly when I was climbing stairs. Night videos will also exhibit more micro-jitters than daytime footage. Overall, I am very happy with the video footage, and considering the phone is so small and lightweight, I think it will be one of my go-to travel cameras.

In fact, Asus thought of this and has designed a case attached to a retractable string that can then be clipped onto a backpack strap or a chest strap. The idea is the Asus Zenfone 9 can be an action camera that adventurers can leave strapped to their chest at all times. I didn’t get the chance to try this case accessory, but I definitely plan on getting one to use for my personal travel vlogs.

Still Photos

It’s unusual for me to focus on the video performance of a camera before still photos, but I did so here because the gimbal stabilization is unique, and the Zenfone 9’s cameras can produce photos of inconsistent quality. Sometimes, when the lighting is right and my hand is still enough, photos from the main camera can look great, with vibrant colors, excellent sharpness, and a bit of real bokeh.

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But the shutter is a bit slow even during the day, and so at night when phones tend to dial down the shutter speed and resort to night mode, I have to keep perfectly still, or else shots will appear blurry. I took the Zenfone 9 for a night out with friends and snapped over 100 photos, and probably 25 of them had blurry subjects. Asus’ color science is also overly contrasty, particularly the reds.

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I want to make this clear: I am nitpicking here because I’m used to testing the absolute top flagship camera phones. And if I actually consider the Zenfone 9’s significantly lower price tag, then the cameras are fine. If I compare the Asus Zenfone 9 camera against something like an iPhone 13 Mini, Asus’ cameras absolutely hold up.

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The ultra-wide and selfie cameras can be evaluated the same way — it’s absolutely fine in a vacuum, or in this price range, but naturally loses to more expensive flagship phones. Ultra-wides look great during the day, but in lower light scenes, the photos start showing a lot of noise and a significant drop in sharpness. The selfie camera also suffers from the slow shutter of the main camera — if I shoot in low light conditions the subjects must stay still for well over a second and a half, or else someone’s face will be blurry.

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I have added full-resolution images in the Flickr album below for those who may want to pixel peep for themselves. Ultimately, the Zenfone 9’s camera system is solid in photography and very good at videography. At the risk of beating a dead horse — at this $699 price, Asus has more than delivered. The only realistic complaint Asus should look into is fine-tuning color science and the shutter speed during the day. Otherwise, it’d be unrealistic to demand a larger image sensor or a real zoom lens.

Asus Zenfone 9: Software

• Has almost every shortcut gesture I can think of
• UI design is very one-hand friendly — even if the screen was bigger
• Fast performance

The Zenfone 9 runs Android 12 with Asus’ ZenUI on top, and I’m a big fan. ZenUI looks simple and clean like vanilla Android, but it’s jam-packed with customization options that offer shortcuts to pull off smartphone tasks. For example, the capacitive touch bar mentioned earlier can be customized to perform different actions when swiped. The power button too, can be assigned specific tasks when long pressed or double pressed.

Almost every third-party shortcut gesture I can think of, like double tap to lock screen, three-finger swipe down to grab a screenshot, or draw a shape on a sleeping screen to control music playback, are all here. There’s a one-hand mode (even though you will almost never need it with this phone), and there’s the ability to make back swipe gestures less or more sensitive. There’s the ability to double tap on the back of the phone to trigger an action. It’s quite overwhelming the number of things you can do and customize here.

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One-handed-ability

Considering the screen is just 5.9-inches, the Zenfone 9 is obviously an easy one-hand phone, but I think ZenUI is so well optimized to account for one-hand usage that even if the screen was something like 6.3-inches, it’d still be very easy to use one-handed.

Apps in a folder, for example, open in the bottom half of the screen so they can be easily reached by thumb. It’s such a logical type of design element that somehow most phone brands do not offer us. Apple’s iOS, for example, opens a folder smack dab in the middle of the screen, which is fine on the iPhone 13 Mini, but imagine this on an iPhone 13 Pro Max.

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And therein lies one of my biggest gripes with the whole iPhone Mini experience: Apple had to make the phone overly small just to compensate for the fact that iOS is not one-hand friendly.

Apple had to make the phone overly small just to compensate for the fact that iOS is not one-hand friendly

On an Android phone, even if I’m using a 6.7-inch screen, I can just place all my most used apps at bottom of the home screen for easy thumb reach. That can’t be done on an iPhone, where apps must sit in top-down, left-to-right order. So either I fill my home screen entirely with apps (which I don’t like doing because I find that clunky) or deal with the fact that apps are higher up on the screen than desired. Look at the photo I snapped a year ago below, of an iPhone 12 Pro Max and an LG Wing — which phone seems easier to use with one hand?

iPhone fans think phone screens must drop to iPhone SE or iPhone Mini petite sizes to be easily used with one hand. That’s not the case. The Zenfone 9’s 5.9-inch screen is easier to operate one-handed than even the Mini’s 5.4-inch screen and makes the 6.1-inch iPhone 13 screen feel unwieldy.

Asus Zenfone 9: Performance and battery life

• Snapdragon 8 Plus Gen 1 is very battery efficient
• One of the smoothest phones we’ve ever tested

This section was written by my colleague and XDA Senior Technical Editor, Adam Conway.

The Asus Zenfone 9 is one of the first smartphones to hit the shelves with Qualcomm’s all-new Snapdragon 8 Plus Gen 1, and it’s likely going to be the first to reach the United States. While this is a “Plus” variant of the chipset, we’ve observed when testing the Asus ROG Phone 6 Pro that this particular chipset represents more of a year-on-year improvement than just a mid-cycle refresh.

The Snapdragon 8 Plus Gen 1 features an improved Qualcomm Kryo CPU, with a Cortex-X2 prime core clocked at 3.2Ghz, three Cortex A710 performance cores clocked at 2.8GHz, and four Cortex A510 efficiency cores clocked at 2.0GHz. Qualcomm claims that the upgraded CPU is 10 percent faster than the one on the Snapdragon 8 Gen 1 and offers 30 percent better CPU power efficiency. We made similar findings in our testing of the Snapdragon 8 Plus Gen 1 reference device that Asus previously shared with us.

CPU Throttling Test

CPU Throttling Test is a freely available app on the Google Play Store, and it repeats a simple multithreaded test in C for as short as 15 minutes. We increased the length of time to 30 minutes. The app charts the score over time so you can see when the phone starts throttling. The score is measured in GIPS — or billion operations per second. It’s essentially a test that can measure the sustained performance of a chipset. The phone gets extremely hot when I run this test, almost burning my hand to the touch, but I’ve never experienced that in any other scenario on this device.

The Asus Zenfone 9 throttles pretty heavily after a while, but that’s because of how hot it gets. Because it’s a smaller device, there’s less surface for heat dissipation.

UI Stutter/Jank test

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To quantify how well the Asus Zenfone 9 can maintain 120 FPS in real-world scenarios, we ran a modified version of Google’s open-source JankBench benchmark. This benchmark simulates a handful of common tasks you’ll see in everyday apps, including scrolling through a ListView with text, scrolling through a ListView with images, scrolling through a grid view with a shadow effect, scrolling through a low-hitrate text render view, scrolling through a high-hitrate text render view, inputting and editing text with the keyboard, repeating overdraws with cards, and uploading bitmaps. Our script records the draw time for each frame during the test, eventually plotting all the frames and their draw times in a plot along with several horizontal lines representing the target frame draw times for the four common display refresh rates (60Hz, 90Hz, 120Hz, and 144Hz).

The results demonstrate just how smooth the Asus Zenfone 9 is when it comes to overall usage. Pretty much all actions are capable of maintaining a consistent 120 FPS, which will be reflected in the overall usage of the phone. From these results alone, the Asus Zenfone 9 is one of the smoothest smartphones we’ve ever tested in terms of general usage.

Battery life and charging

The Asus Zenfone 9 packs a 4,300 mAh battery, which is about right for a small phone. The smaller display coupled with the more efficient chipset ensure long-lasting battery life, though, and I’ve been able to get as much as eight hours of screen on time on a single charge. Typically it’s between six and seven hours, though.

I know that from Ben’s experience, his battery life hasn’t been quite as good, though he also mentions that he takes a lot of photos and shoots a lot of video. This will put any phone’s battery under stress, and it’s still a phone that Ben says will give him five to six hours of screen on time. The phone lasts him a 12 to 13-hour work day, which is more than any other small phone could do in his experience.

As for me, this phone has some of the best battery life of this generation of smartphones. The screenshot above is from a full day of usage of the phone, where I spent most of the day out and about. This is the best battery life that I’ve had in a long time on a phone.

To be honest, nearly every Snapdragon 8 Gen 1 device has given me subpar battery life, whereas the Snapdragon 8 Plus Gen 1 is looking to be an absolute success. Asus likely has some level of software optimization going on here that contributes to some of it, but it’s clear as well that this chipset is just a lot more efficient than the regular Snapdragon 8 Gen 1.

The only issue that I’ve faced with battery life and charging is an inconsistent charging time — oh, and absent wireless charging. The charging time though in particular has been awful, as at times with the official charger supplied in the box it has taken well over an hour to charge, and more like an hour and a half. I’ve also used the 65W charger that came with the Asus ROG Phone 6 Pro and I got the same results, so I’m unsure of what the cause is. Nevertheless, with such great battery life you’ll only really need to charge this device once a day anyway.

Asus Zenfone 9: Should you buy it?

You should buy the Asus Zenfone 9 if:

• You want a phone that can be used easily with one hand.
• You shoot a lot of vlogs and want better stabilization.
• You want a near-flagship phone without paying four-digit prices.

You should not buy the Asus Zenfone 9 if:

• You want a camera that always performs well day or night.
• You enjoy taking zoom photos.
• You have bad eyesight and often struggle with smaller text, and hence, could better use a bigger phone.

The Asus Zenfone 9 is, simply put, the best small phone today. But even if the size thing doesn’t matter, the Zenfone 9 is an absolutely great value, particularly in the North American space. To get a Snapdragon 8 Plus Gen 1, a gimbal camera system that really works, a vibrant display, in a well-designed package that’s easy to hold, for just $699? Absolute no-brainer recommendation for most people.

I’m glad Asus had the foresight to pivot the Zenfone series to a smaller form factor to differentiate itself from the sea of smartphones because as much as I enjoy how every 2022 flagship is a good performer, I am starting to feel a bit of boredom as they all look and feel the same. The Zenfone 9 is a breath of fresh air.

Asus Zenfone 9

Asus Zenfone 9

The Asus Zenfone 9 is a small phone that packs a powerful flagship chip and a gimbal camera system that works.

$649 at Amazon