Asus Zenfone 9 review: Pint-sized powerhouse

The Asus Zenfone 8 offered a rare proposition: a relatively compact Android flagship at a mid-market price. The Asus Zenfone 9 takes that commendable philosophy and attempts to create something even more memorable and ambitious.

With Android phones gradually getting bigger and bulkier by the year, it’s a breath of fresh air to encounter a phone that’s been designed with one-handed use in mind. Despite this downsizing, the Zenfone 9 is remarkably low on compromise, though it’s there to be found if you look closely.

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Asus Zenfone 9 review: What you need to know

The Asus Zenfone 9’s big selling point is top-notch performance from a compact body. To that end, Asus has managed to cram the very latest Snapdragon 8 Plus Gen 1 chip into a chassis that measures just 147 x 68 x 9.1mm and weighs a mere 169g.

This petite frame is fronted by a 5.9in FHD+ 120Hz AMOLED display, which is downright small by modern Android standards. You also get a dual camera system led by a 50MP Sony IMX766 sensor, with a 6-axis gimbal system keeping shots freakishly steady.

With these specs and dimensions, wrapped up in a broadly familiar squared-off design, Asus is essentially giving us the closest thing yet to an Android-powered iPhone 13.

Asus Zenfone 9 review: Price and competition

As much as I loved my time with the Asus Zenfone 9, and as unique an offering as it is within the Android world, it feels a tad on the expensive side. You’re paying £699 for the 8GB of RAM/128GB storage model, while £749 lets you double both capacities. That’s a £100 premium over last year’s Asus Zenfone 8.

Now consider the main competition. The iPhone 13 Mini offers an even more compact phone with comparable performance, a superior camera, wireless charging and a less compromised design, all for £20 less. Rumour has it the Mini line will soon be retired, but you can bet Apple will continue supporting the iPhone 13 Mini for years to come.

There are far fewer Android phones that offer a similar mixture of performance and compactness. The Sony Xperia 5 III, Xiaomi 12, and Galaxy S22 are generally classed as compact flagships, but all are larger and slower than the Zenfone 9, and all have slightly higher RRPs.

Still, if you’re willing to go a little (okay, a lot) bigger, the Pixel 6 gives you a premium Android experience with wireless charging and a superior camera for £599. So the question is, just how much do you want a compact Android flagship?

Asus Zenfone 9 review: Design and key features

The ultra-dinky Asus Zenfone 9 has a seriously striking new look. It’s another Android phone to adopt the modern flat-sided design pioneered by the iPhone, but Asus has made more of an effort than most to make its phone stand apart.

The Taiwanese manufacturer has adopted a unique high-grip polymer material for the rear of the phone, with a soft yet textured feel that falls somewhere between fake leather and the coarse moulded cardboard that eggs come in. This has the benefit of being extremely grippy, as well as being lighter and more shatter-resistant than glass and extremely resistant to fingerprints.

On that latter front, one of my big worries when I handled the Zenfone 9 for the first time was whether the soft-touch rear would wear badly, especially in my review model’s Moonlight White shade (the other colours being Sunset Red, Midnight Black and Starry Blue). It’s too short a test period to say for sure, but I can say that it has stood up well to almost two weeks of solid usage, which included a heatwave making things particularly sweaty. IP68 certification is another sign that it’s built to last.

Those flat aluminium edges house some interesting details of their own, including an area that extends further where the phone’s responsive power button/fingerprint sensor sits. There’s a similar effect where the 3.5mm headphone jack lies on the top edge. Yes, Asus found space to include such a thing where most larger flagships don’t.

Even the bottom edge houses a quirky detail in the form of a dual-SIM tray that starts to curve into the left hand corner. You’ll also find the second of the Zenfone 9’s stereo speakers on this edge, as well as the USB-C port.

I have only two disappointments with the Asus Zenfone 9’s design, and both lie on the front of the phone. What otherwise feels like a premium device appears to compromise with its non-uniform bezels. The phone’s forehead is thicker than its side bezels, and the chin is even thicker still.

Together with the kind of distractingly reflective hole-punch selfie camera housing that you typically see in cheap phones, the front of the Zenfone 9 doesn’t quite match its chic rear. It makes me wonder what an Asus Zenfone 9 Pro might have looked like.

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Asus Zenfone 9 review: Display

The Asus Zenfone 9 is fronted by the same 5.9in FHD+ (2,400 x 1,080) Samsung AMOLED display as last year’s Zenfone 8. You won’t find any complaints here, as it’s a bright, crisp, colour-accurate screen.

There are four screen colour modes on offer, but only the Normal mode supplies the requisite goods in strict colour accuracy terms. With this mode selected, my colorimeter recorded an excellent average Delta E score of 1.14 when tested against the sRGB colour space.

In this mode, it also recorded a 98.1% sRGB gamut coverage, with a 99.5% sRGB gamut volume. Again, this is strong stuff.

The phone’s manual brightness slider peaked at a respectable 415cd/m² with autobrightness switched off. Asus claims it will hit a more than respectable 1,100cd/m², but this isn’t a brightness I noticed in testing.

Besides its inherent quality, the most notable thing about this display is that it’s a lot more manageable with one hand. There’s that smaller-than-average 5.9in size, of course, but Asus has also implemented some handy hardware and software workarounds.

Swiping down on the power button can bring the notification shade down, while swiping down on the app dock brings the top half of the screen to within reach of your holding thumb. Those who like to walk and text won’t find a better-suited Android phone right now.

Asus Zenfone 9 review: Performance and battery life

One of the most exciting specs with the Asus Zenfone 9 is the presence of a Snapdragon 8 Plus Gen 1 processor. That’s the very latest flagship Qualcomm offering, and the same chip that Asus is using to power its monstrous ROG Phone 6 gaming phone. That results in extremely strong performance, as you might expect.

While Asus has provided its phone with a 230% larger thermal system compared to the Zenfone 8, however, you can’t get around those darned physics. This is a small phone, which means less internal space and more heat.

I found that the Zenfone 9’s aluminium frame got uncomfortably hot when the phone was under high load, such as in the 20-minute 3D Mark Wild Life Extreme test or when downloading a particularly large file. It also throttled performance way back in the later loops of that aforementioned 3D Mark test.

Of course, most people won’t be pushing the Asus Zenfone 9 that hard for extended periods. In more regular benchmark tests, performance proved exemplary, with an average Geekbench 5 multicore score of 4,317 blitzing compact rivals such as the Xiaomi 12 and getting within spitting distance of the iPhone 13 Mini. GPU performance is even hotter (pun unintended), with GFXBench scores that trump every other compact rival to date, including the mighty iPhone.

Practically speaking, the Zenfone 9 doesn’t miss a beat, with smooth navigation and lightning fast app-switching times. It’s every inch the flagship phone in the hand.

Battery life is decent rather than great, but that’s a good thing given the smaller-than-average 4,300mAh cell that’s been packed into that compact body. I was routinely able to get through a full 16-hour day of around four hours of screen-on time with about 30% charge left.

Charging speeds aren’t too impressive given the tiny size of that battery, likely thanks to the provision of a mere 30W HyperCharge adaptor. I was able to get the phone to 44% in 30 minutes, while a full charge took a leisurely 1hr 35mins.

A battery test score of 17hrs 53mins beats the iPhone 13 Mini, but falls an hour or so short of the Xiaomi 12 and several hours short of the Sony Xperia 5 III and the iPhone 13. It’s a predictably OK-but-not-outstanding result.

It’s a shame there’s no wireless charging here, too. Yes, that space-saving explanation is somewhat valid, but again, Apple managed to squeeze such a feature into the iPhone 13 Mini.

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Asus Zenfone 9 review: Cameras

The Asus Zenfone 9 goes with a mercifully simplified dual-camera system. You get a 50MP main and a 12MP ultrawide, with no additional depth or macro sensors cluttering things up.

The main sensor is a Sony IMX 766, which we’ve seen recently in the OnePlus Nord 2T and the Realme 9 Pro Plus, and before that in the flagship Oppo Find X3 Pro. As that suggests, it’s no longer a truly cutting-edge “flagship” sensor, but it’s still capable of scooping up plenty of light and capturing detailed, well-exposed shots.

That’s particularly so with the Zenfone 9’s secret weapon in tow: a 6-axis hybrid gimbal system. This goes beyond your average OIS system in keeping the lens stable, which means that low-light shots in particular are sharper than usual, while videos (8K/24fps or 4K/120fps) are super-steady. Night shots taken with the Zenfone 9 are particularly decent, so long as your subject remains still.

It’s not perfect, however. I picked up some strange visual artefacts when taking landscape shots in dusky conditions, with weird shadows appearing in the sky near flying birds. This applied to both cameras, while in one shot the ultrawide also threw in some weird oblong shapes in the sky for good measure.

The ultrawide is of a much lower order too, with significantly less detail and inferior exposure. The tone isn’t a million miles away from the main sensor, at least, though there’s less depth to the colours.

You won’t find a dedicated telephoto camera here, with Asus again citing space constraints. Thanks to the surfeit of pixels on that main sensor, the cropped-in 2x mode yields acceptable results at a pinch.

Around the front there’s a 12MP selfie camera that acquits itself well, with solid subject isolation and a reasonably natural-looking bokeh effect, doubtless courtesy of autofocus. Exposure is on point, and I appreciated the fact that it didn’t blow out the highlights on my sunny day shooting.

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Asus Zenfone 9 review: Software

The Asus Zenfone 9 runs on Android 12, with the company’s Zen UI layered on top. It’s a mercifully lightweight skin that preserves much of the Google goodness underneath, with a familiar notification shade, menus and app icons.

Google Feed is located to the left of the homescreen, as it should be, and the only duplicate app is for the Gallery. I would prefer there to be no third-party installations at all, but that’s perhaps an unreasonable expectation. At least Netflix, Instagram and Facebook are justifiable inclusions.

Asus is promising two major Android updates, and at least two years of security updates. This doesn’t make it the most future-proof phone out there, but it’s reassuring that it will be supported for the length of a phone conctract nonetheless.

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Asus Zenfone 9 review: Verdict

The Asus Zenfone 9 is one of the most enjoyable-to-use Android phones I’ve reviewed all year. Its new design is fresh and appealing, performance is blistering, and its compact body will come as a sweet relief to anyone who bemoans the ballooning state of modern Android flagships.

Any iPhone users looking to make the switch to Android, meanwhile, will struggle to find a phone that makes the transition any easier. It’s not without its flaws, however, and there’s definite room for improvement.

The Zenfone 9 arguably either needs to be a little cheaper, or it needs a little more refinement for its newly elevated asking price. That design, while sharp from most angles, falls short from the front, and the phone lacks wireless charging. Meanwhile the camera, while mostly solid and impressively steady, isn’t top of its class, and throws up some weird artefacts in low-light shooting.

It’s still a hugely impressive effort, however, and a phone that faces very little competition within its pint-sized flagship niche.