Asus Zenfone 9 review: Small smartphone, big power With the Zenfone 9, Asus presents a “mini flagship” under 6 inches with currently the fastest Qualcomm processor. The test reveals how good the Kraftzwerg is. 4:15 p.m. tech stage

The computer giant from Taiwan has already shown with the Asus Zenfone 8 (test report) that it can build powerful smartphones in a compact format. The Asus Zenfone 9 is a more than worthy successor. The first technical specifications make you sit up and take notice: A Snapdragon 8 Plus Gen 1 promises enormous power, and the magic word “gimbal” also appears on the main camera. In the test, we explain what it’s all about and whether the Zenfone 9 really comes through as a mini flagship.

We show a selection of other compact mobile devices in the top 10 of the mini mobile phones: The best small smartphones . We present even more alternatives and “sub-flagships” in the article Top performance at a fair price: top smartphones up to 750 euros .

The Asus Zenfone 9 is relatively compact for an Android smartphone and also extremely stylish. When you hold the phone in your hand for the first time, you immediately notice the material on the back. This is soft and cushioned, offers so much grip and feels pleasantly organic. The mobile phone’s housing, on the other hand, is surrounded by a solid metal frame. Two concise round openings for the two camera lenses are very noticeable on the back – this is quite reminiscent of Honor and Huawei. The predecessor seemed rather stuffy in comparison .

The dimensions are 146.5mm x 68.1mm x 9.1mm. The Zenfone 9 is relatively light at 169 g. In terms of size and weight, it roughly corresponds to the Samsung Galaxy S22 (test report) or iPhone 13 (guide) . The smartphone is not exactly slim, but it is very compact for an Android device. In terms of size, the Zenfone 9 remains largely true to the 8 model. It is also well protected against water and dust and has an IP68 certification. We show more waterproof cell phones in the top 10: Waterproof smartphones with IP certification .

Compared to the predecessor, everything remains the same on the display: the diagonal measures 5.9 inches with an elongated format of 20:9. The resolution of 2400 x 1080 pixels ensures a sharp image reproduction with 446 ppi (pixels per inch). OLED is again used as the panel, which flickers at up to 120 Hertz. The sampling rate is 240 Hertz.

The image quality is absolutely convincing. Contrasts, colors and viewing angle stability are pronounced. There are also customization options for the color display to choose from. If you want to reduce battery consumption, you can gradually reduce it to 90 or 60 Hertz. Automatic selection of the refresh rate is also possible. Gorilla Glass Victus is also responsible for increased protection against display breakage. At almost 800 cd/m², the brightness is more than high enough to be able to read the display even in sunshine.

Unlike many smartphones from the Far East, the Asus Zenfone 9 only uses two lenses: a main lens and a wide-angle lens. The primary camera uses the Sony IMX766 sensor with 50 megapixels. The camera combines four pixels into one using pixel binning, resulting in photos with around 12.5 megapixels.

The biggest highlight, however, is likely to be the optical image stabilization (OIS) via a gimbal gimbal on six axes. This enables movement corrections at a tilt angle of up to 3 degrees, a conventional OIS usually only manages up to 1 degree. However , this “gimbal” stabilization does not make the Zenfone a real action cam like the Insta360 One X2 (test report) . But video clips hardly shake when the user goes up a flight of stairs. With an active gimbal, however, only resolutions up to Full HD are possible. 4K recordings only succeed with “normal” stabilization.

Photos in daylight are good thanks to the HDR automatic. Colors look natural and contrasts are pronounced. The image details are okay, but could do with more sharpness in the background. Due to the lack of a telephoto lens, only a digital zoom is available, which, beyond double magnification, only leads to pixelation for distant objects. The slight zoom works well for close-ups, proving that macro sensors are unnecessary in smartphones. The depth of field in portrait mode is also successful.

The ultra-wide-angle lens is identical to that of the Zenfone 8 and uses the 12-megapixel Sony IMX363 sensor. In terms of color representation and image dynamics, wide-angle shots hardly differ at all from photos taken with the main lens. Only the edges appear a little more washed out, and the parts of the image in the middle are less pronounced. A 12-megapixel camera is embedded in a punch-hole notch on the front. This ensures decent selfies and a successful bokeh effect.

The Zenfone 9 is powered by the Snapdragon 8 Plus Gen 1 – an improved version of Qualcomm’s new high-end processor. This should bring up to 10 percent more power, but still run more efficiently and thus more energy-efficiently than its predecessor. The production also takes place at TMSC and no longer at Samsung. Our benchmarks confirm the increase in performance: The Zenfone 9 achieves around 16,500 points in PCmark Work 3.0. This is a strong value, but it is on a similar level as the previous model with Snapdragon 888.

3Dmark then gets down to business: Our usual “Wild Life” test, like the iPhone 13 Mini (test report) , only spits out the statement: “busy”. In “Wild Life Extreme”, the Zenfone 9 then achieved an impressive 2800 points. It is even just ahead of the iPhone 13 Mini in the test, which also achieved a strong 2300 points. Both devices use different operating systems, which somewhat limits comparability. The Sony Xperia 1 IV (test report) with the “normal” Snapdragon 8 Gen 1 gets around 2100 points. However, Qualcomm was not able to completely solve one problem: The cell phone gets very warm under load, as in Wild Life Extreme. We don’t notice that as much in everyday use, but it gets hot as soon as the performance limits are reached in games.

As far as the processor is concerned, the Zenfone 9 runs quickly, smoothly and without stuttering and is therefore also an option as a gaming smartphone. The main memory is also generous with 8 GB, there is also the top version with 16 GB RAM. The internal memory is 128 or 256 GB depending on the version. Fast flash memory according to UFS 3.1 is installed. However, it is not possible to expand the memory using a microSD card. A bit disappointing: the Type-C port only works with USB 2.0. And that’s not only a disadvantage on paper with a maximum of 480 Mbit/s, but also in practice, for example when copying a large music collection to a cell phone. At the price, at least USB 3.2 with 5 GBit/s would have been appropriate. Our guide offers more on the subject of USB interfacesUSB-C, Thunderbolt 4 or USB 4: This is what you need to know when buying a USB-C cable . All the more gratifying: there is a simple slot for headphones with a 3.5 mm jack.

As far as wireless connectivity is concerned, everything is up to date: Bluetooth 5.2 with aptX Adaptive, NFC and fast Wi-Fi 6E. The cell phone also uses almost everything in orbit for localization: GPS, Glonass, Beidou, Galileo, QZSS and NavIC. The stereo speakers provide decent sound for games or video clips. The fingerprint sensor is located in the power button and works quickly and reliably. As with the predecessor, you can assign additional functions to the power button, either by double-clicking or by pressing the button longer. Face recognition is also possible, but due to the 2D technology, it is not sufficiently protected against deception with photos or people who look similar. We recommend the combination of PIN and fingerprint.

The operating system is Android 12. Asus’ user interface is strongly based on vanilla Android, but it adds useful features and settings, such as different performance modes and a stylishly animated home screen. The security patch is up-to-date and dates from August 2022 at the time of testing. Asus usually offers its smartphones version and security updates for 2 years. That’s a bit small compared to Samsung or HMD Global. This makes the Zenfone 9 a good candidate for Android 13 (guide) and maybe also the next version.

Small mobile phones often have a catch: the batteries are often rather weak. However, compared to its predecessor, the Zenfone 9 offers a 7 percent higher battery capacity of 4300 mAh. That’s not bad for a small device, even if it can’t compete with the up to 5000 mAh of larger smartphones.

The result of the PCmark battery test is still a positive surprise. We get a simulated runtime of more than 10 hours – even at 120 Hertz. The predecessor didn’t even come close to doing that. This puts the Zenfone 9 in the middle of the range in our tests – and that for a small device with such a powerful CPU. Only the Realme GT Neo 2 (test report) lasted a similarly long time despite the Snapdragon 8 Gen 1 – but with 5000 mAh.

The charger, which works with 30 watts and supports USB-PD 3.0 and Qualcomm Quick Charge 4.0, is anything but a turbo. The smartphone is charged in just under 90 minutes. It cannot charge wirelessly.

The RRP for the Asus Zenfone 9 with 8/128 GB is 799 euros, for the variant with 8/256 GB the manufacturer calls 849 euros, with 16/256 GB it costs 899 euros. Black, white and blue are available as colors. If you order the Zenfone 9 directly from Asus, you get a free Chromebook .Conclusion

The Asus Zenfone is currently one of the most powerful smartphones out there and is extremely compact for an Android smartphone. With the size of an iPhone 13, it still fits well in any trouser pocket. In our opinion, a few features are still missing for a fully-fledged flagship, such as a telephoto lens and a faster USB interface. The equipment still leaves little to be desired, even the battery life is okay despite the power.

The Samsung Galaxy S22 (test report) is similar in size, also fast and equipped with a telephoto lens . However, the battery doesn’t last as long as in the Zenfone. If you are looking for a really compact alternative with a lot of power, you can hardly avoid the much smaller iPhone 13 Mini (test report) . Our top 10 mini cell phones show other space-saving smartphones: The best small smartphones . We also present good alternatives in the article Top performance at a fair price: Top smartphones up to 750 euros .