There's a second model the ZenFone 4 Max. The Max refers to a huge 5000mAh battery, not a larger screen. You can see the full specs of both phones below.
How much does the Asus ZenFone 4 cost?
What are the ZenFone 4's specs?
Here are the key specs in a handy table, so you can compare the two models.
|ZenFone 4||ZenFone 4 Max|
|Operating system||Android 7.1.1 Nougat||Android 7.1.1 Nougat|
|Available colours||Moonlight White, Midnight Black||Deepsea Black, Rose Pink|
|Display||5.5in (1920x1080, 401ppi) IPS||5.5in (1280x720,) IPS|
|Processor||Snapdragon 630, octacore at 2.2GHz||Snapdragon 430, octacore up to 1.4GHz|
|GPU||Adreno 508||Adreno 505|
|Storage||64GB + microSD up to 2TB||32/64GB + microSD up to 2TB|
|Primary cameras||12Mp f/1.8 OIS + 8Mp (120° wide-angle)||13Mp f/2.0 + 8Mp (120° wide-angle)|
|Front camera||8Mp f/2.0||8Mp f/2.0|
|Video recording||2160p at 30fps EIS, 1080p at 60fps||1080p at 30fps|
|LTE||Cat 12||Cat 4 (150Mb/s)|
|SIM||Dual nano-SIM (second slot shared with microSD)||Dual nano-SIM (plus microSD slot)|
|Fingerprint scanner||Yes, front||No|
|Audio||Stereo speakers + Hi-res audio support||Mono speaker|
|Battery||3300mAh, non-removable||5000mAh, non-removable|
|Charge / Sync||USB-C||micro USB|
|Dimensions||75.2x155.4 x7.5mm||76.9 x 154 x 8.9 mm|
It's clear that the ZenFone 4 bears more than a passing resemblance to the 5.5in iPhone, and it even shares the same 1920x1080 resolution.
Like the iPhone 7 Plus and 8 Plus - and many new phones - there's a dual-camera setup at the rear.
Unlike the majority, though, Asus has gone for a 12Mp main camera and a secondary 8Mp sensor with a wide-angle lens.
The former uses Sony's flagship IMX362 sensor and it focuses using dual pixel phase-detection autofocus (PDAF). Asus says at 0.03 seconds, it's the world's fastest.
The camera also benefits from optical stabilisation on four axis which allows long(ish) exposures of 1/4 sec.
and image processing is handled by a Qualcomm Spectra 160 chip.
The wide-angle camera isn't ultra-wide like LG's recent phones, but it has a 120° field of view which lets you fit a fair bit more in the frame without introducing too much distortion.
There's plenty of flagship-level components including Cat 12 LTE, Bluetooth 5, 802.11ac Wi-Fi, and you get extras missing from the 'Max' version such as USB-C, hi-res audio, stereo speakers, a fingerprint sensor and NFC.
Asus keeps the price down by sticking with a full HD screen rather than quad HD, and there's no waterproofing.
ZenFone 4 Max
Similar in name and design, but very different inside, the Max is intended to offer huge battery life for those on a tighter budget that don't care so much about having the best cameras and fastest processor.
The ZenFone 4 Max can act as a power bank and charge other devices thanks to the included OTG USB cable.
It has a similar dual camera setup to its pricier stablemate, but although the 13Mp main camera has extra resolution, it doesn't have optical stabilisation.