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Asus Zenfone 2 review: RAMbunctious

Initially presented at CES 2015, the Asus Zenfone 2 – the world’s first smartphone to ship with a 64-bit processor and 4 GB of RAM, was a bit of a showstopper. But perhaps the most spectacular part of the Zenfone 2 isn’t its specs sheet, but its price: the ''lighter'' version of the Zenfone 2, with 2 GB of RAM and 16 GB of internal storage, starts at just 199 USD, with US pricing for the 4 GB version to be announced at an event in New York City on May 18. Check out our Asus Zenfone 2 review (the 4 GB of RAM version - model ZE551ML) for more details.



  • Incredibly low price
  • 4 GB of RAM, 64-bit CPU
  • Customizable ZenUI
  • Pixel Master low-light technology
  • Premium looks and build quality
  • Dual-SIM and microSD card slots
  • Fast charging battery: 60% in 40 mins.


  • Capacitive buttons (non-illuminated)
  • Generally mid-range specs
  • Display is not so bright outdoors

ASUS Zenfone 2 release date and price

The Zenfone 2 release date was May 19, 2015. The Asus Zenfone 2 price is 199 USD for the 16 GB/2 GB RAM/720p/1.8 GHz version. The ''flagship'' version, with 64 GB/4 GB RAM/1,080p/2.3 GHz is an incredibly low 299 USD. See the ''Where to buy'' section at the bottom of this reveiew for more details.

ASUS Zenfone 2 design and build quality

Considering the very low price of the Zenfone 2 (at this point we know that you can pick up a 4 GB Zenfone 2 on Amazon and eBay for between 325 - 399 USD for the 32 GB and 64 GB models respectively, giving you an idea of what the final US price will be), you might be forgiven for thinking that it would look, well, cheap. But you couldn’t be more wrong.

The Zenfone 2 sits very nicely alongside the LG G3 and HTC One (M8) in the looks stakes, and they are still two of the best looking phones around. In terms of size, it's pretty close to the LG G4.

asus zenfone 2 back
The Asus Zenfone 2 styling is like a mix of the HTC One (M8) and LG G3. / © ANDROIDPIT

The Zenfone 2 has a curved ''brushed aluminum'' plastic back plate that aids with grip thanks to the slightly textured surface. The phone sits very nicely in the hand and has centered volume buttons on the back like the G3, along with a camera sensor, dual-LED flash and speaker grill at the bottom.

The power button sits up top in the center, which is admittedly a little awkward, much like it is on the HTC One M8. While everything looks great, the plastic is a litttle creaky and despite having a removable back panel, the battery is non-removable.

asus zenfone 2 headphone jack
The Asus Zenfone 2 styling is like a mix of the HTC One (M8) and LG G3. / © ANDROIDPIT

On the front you’ve got the unfortunate addition of capacitive buttons, which are not illuminated, making them a little hard to see in some circumstances (like at night). These buttons are, like the HTC One M8, positioned in a black band underneath a otherwise nice and big 5.5-inch screen.

The side bezels are a little chunky, but the overall screen real estate on the Zenfone 2 is an impressive 72%. The build quality of the Zenfone 2 is truly impressive considering the price at which it is being offered and you’ve got black, gold, gray, red and white color options.

asus zenfone 2 front camera
The Zenfone 2 has a Full HD IPS display that hits 400 nits of brightness. / © ANDROIDPIT

ASUS Zenfone 2 display

The Zenfone 2 has a nice bright 5.5-inch IPS LCD display with Full HD resolution and 403 pixels per inch. An anti-fingerprint coating on the Corning Gorilla Glass 3 reduces friction by 30% making for a super-smooth touchscreen experience and of course it reduces fingerprints too.

The display can bump up to 400 nits and it looks great with good contrast and saturation and very impressive viewing angles. The screen is actually one of the high points of the ZenFone 2. Sure, it's ''only'' Full HD (1,920 x 1,080 pixels), but it's really quite good.

asus zenfone 2 screen
The Zenfone 2 is running Android 5.0 Lollipop and ZenUI on a nice Full HD 5.5-inch screen. / © ANDROIDPIT

On the downside, the display picks up a lot of reflections and glare, which may be due to the anti-fingerprint coating. This fact, combined with the brightness, make it quite hard to see outside on a bright day. That ear piece just above the screen is also a dust magnet and will soon be full of pocket lint and fluff.

zenfone 2 test
Outside though, the Zenfone 2 struggles in sunlight with brightness and reflections. / © ANDROIDPIT

ASUS Zenfone 2 software

The Zenfone 2 doesn’t slack off in the software department either, running Android 5.0 and a completely reworked ZenUI which is completely customizable from top to bottom, providing a native custom look without the need for additional customization tools and apps.

The interface may not be to everyone’s liking (I’m looking at you, icons), but the Quick Settings menu and notifications shade are a blend of stock Lollipop and the new-look TouchWiz, but with a more subdued color palette.

AndroidPIT Asus Zenfone 2 ZenUI 1
I'm not a fan of the icons but everything about ZenUI is customizable. / © ANDROIDPIT

On initial setup, you've got Lollipop's Tap & Go feature for transferring the contents of your old phone to your Zenfone 2, but then you've also got Asus' Data Transfer which does basically the same thing. This can be a little confusing but two options are better than none.

You can also score 100 GB of free Google Drive cloud storage when you first sign up. I'm not sure how I feel about Trend Micro being pre-loaded though.

AndroidPIT Asus Zenfone 2 camera 2
The Zenfone 2 has a full auto mode in the camera app with Pixel Master technology for low light shooting. / © ANDROIDPIT

One of the best software features of the Zenfone 2 is the impressive Pixel Master technology in the camera: offering up to 400% more brightness in low light situations. This feature was originally demoed to  me at CES by taking a photo of a butterfly inside a completely black box and actually being able to see it clearly where even the Galaxy Note 4 struggled to make out anything at all (to be fair, the Note 4 didn’t have a low-light setting enabled though). 

As per usual, when you swipe a finger down on the home screen, you'll get access to your notifications. But if you swipe a finger up, you'll see the ''Manage Home'' menu. It's kind of a like an additional command panel, where you have access to auto-grouping of apps into folders, quick access to settings, icon packs, wallpapers, home screens, themes and so on.

AndroidPIT Asus Zenfone 2 ZenUI 2
ZenUI brings Lollipop notifications and a TouchWiz-esque look to the Quick Settings. / © ANDROIDPIT

There are some other nifty software features in the ZenMotion settings: Touch Gesture and Motion Gesture. Motion Gesture is simply a ''shake to take a screenshot'' function with a reminder feature. Touch Gesture is more useful and features some classics like double tap to wake, app launch gestures (whereby you draw a letter on screen to quickly launch a pre-selected app) and double tap to sleep.

AndroidPIT Asus Zenfone 2 ZenUI 3
There are some good pre-loaded apps and multi-tasking is a breeze. © ANDROIDPIT

There is also a whole host of Asus apps for various things you'd probably have other preferences for already: messaging, gallery, note taking, file manager and email, but there are a few, like Do It Later for reminders and the weather app which are really quite good.

The AudioWizard is also great: it gives you rapid access to cycle between different audio modes like movie mode, speech, gaming and more. The Zenfone 2 comes with Kids Mode, for more secure loaning of your device and password-protected web access, as well as an FM radio (at least the European version does). 

asus zenfone 2 home button
The Asus Zenfone 2 is great for multitasking, even if it falls down a little on raw processing power. / © ANDROIDPIT

ASUS Zenfone 2 performance

As the world’s first smartphone equipped with 4 GB of RAM and a 64-bit chip (a quad-core Intel Atom clocked at 2.3 GHz), the Zenfone 2 specs are pretty impressive on paper. In practice too, the presence of this hardware package makes short work of all but the most demanding processes, although the processor is nowehre near as powerful as many other high-end chips. Multitasking, however, is a breeze and the overall responsiveness is very quick and fluid.

The addition of Android 5.0 Lollipop adds to the fluidity of the experience and I can only say I am impressed and can confirm that it is very hard to slow this phone down, no matter what you throw at it. Even serious sessions of hi-res gaming (with five 3D games at a time) and endless app switching are easy work for the Zenfone 2. If slow-down under stress has always bothered you in the past, the Zenfone 2 will make you happy.

The Zenfone 2 features a range of hardware options: two versions with 2 GB of RAM and a quad-core Atom chipset clocked at 1.8 GHz, one with a 1080p display and another with a 720p display, and the big one (that we are reviewing here): with 4 GB of RAM, 1080p display and the 2.3 GHz CPU.

androidpit france copyright asus zenfone 2 ze551ml benchmark antutu geekbench 3 images 00
The benchmarking results of the Zenfone 2 are not top-notch, but the general experience of the phone is. / © ANDROIDPIT

There are 16, 32 and 64 GB storage capacities on offer along with microSD expansion. You even get 5 GB of lifetime web storage with Asus and the 100 GB Google Drive storage we mentioned earlier. The Zenfone 2 is a Cat. 4 LTE device with data speeds of 150 Mbps.

We benchmarked the Zenfone 2 to see if those figures matched up with our real-world experience. In AnTuTu, the Zenfone 2 scored just over 47,000 (for comparison, the Galaxy S6 tops 67,000) - a little surprising considering how well it handles multi-tasking, but not so surprising when you consider the relative weakness of the Intel chip compared to the S6's Exynos 7420.

In Geekbench 3, the Zenfone 2 scored pretty poorly too, with a single-core score of 912 and multi-core score of 2945. Again, compared to the Galaxy S6, which scored 1500 and 5100 respectively, you can see where the Zenfone 2 starts to fall down when it is compared with devices that cost three times as much. The takeaway here is multitasking good, raw power not so good.

asus zenfone 2 headphones
Throwing on some headphones and getting busy with serious gaming is what the Zenfone 2 does best. / © ANDROIDPIT

When it comes to graphics, the PowerVR G6430 provides quite competitive performance, with between 153.6 to 230.4 gigaflops (floating point operations per second). By comparison the Adreno 418 in the LG G4 hits 155.5 gigaflops and the Galaxy S6 (with the Mali-T760MP8 GPU) going up to 320 gigaflops.

Of course, performance is not all about the numbers. As you can tell by our commentary above, the graphics and multitasking performance of the Zenfone 2 far surpasses it's raw processing power. As always, take numbers with a grain of salt and try the device out for yourself to see what you think of its performance strengths and weaknesses.

asus zenfone 2 speaker back
Don't be fooled by that big speaker grill, the speaker is actually only on the left side. / © ANDROIDPIT

ASUS Zenfone 2 audio

Despite that nice big speaker grill on the back of the Zenfone 2, if you pull the back cover off you'll quickly see that the speaker itself is quite small and located on the left hand side only. Having said that the audio quality on the Zenfone 2 is pretty impressive. For a phone at this price point you really can't ask for me and to be honest, you're unlikely to find a better speaker on a phone at this price point.

The microphone and speaker for calling are good in both directions. Call quality on the Zenfone 2 speaker is crisp and clear and the same is true when receiving a call from the Zenfone 2 (although it's hard to measure the microphone quality without being entirely dependant on the speaker quality of the phone receiving the call). Audio recordings produce solid results though, which reinforces the experience when receiving calls from the Zenfone 2.

asus zenfone 2 camera flash colume buttons
The Zenfone 2 has a very acceptable 13 MP camera with an aperture of f/2.0. © ANDROIDPIT

ASUS Zenfone 2 camera

As mentioned above, the Zenfone 2 camera features Pixel Master technology, which promises excellent low light performance. The fast shutter speed of the 13 MP camera certainly held to produce good shots in low light which you can see below.

Both the main camera and 5 MP front-facing camera have a f/2.0 aperture and there's a two-tone flash for more natural looking selfies. Pixel Master brings low-light improvements, Backlight (HDR) mode and a manual mode which is very nice to see on such a cheap device.

It goes without saying that the Zenfone 2 camera is not in the same league as the cameras found on the LG G4 or Galaxy S6, but for a phone that only costs half as much or a third of the price as those devices, the Zenfone 2 holds up very well. The 5 MP front-facing camera is also surprisingly good and provides excellent quality selfies and video calling images.

asus zenfone 2 back sd battery sim
The removable cover of the Zenfone 2 reveals a microSD card slot and dual-SIM options but no removable battery. © ANDROIDPIT

ASUS Zenfone 2 battery

The Zenfone 2 has a 3,000 mAh fast-charging battery that is non-removable. With the hardware optimizations of a 64-bit chip and Full HD display, you can expect all day battery life to be no problem. If you're conservative with your usage it's not impossible to hit two days' worth of battery life, but we found one day to be a much more realistic figure.

Fast-charging makes things easier too, so you can load up to 60 percent of the battery's capacity within just 40 minutes. While this doesn't solve the larger battery issue facing the Android world, fast charging is a pretty great stop-gap and it's great that the Zenfone 2 includes it.

asus zenfone 2 front box
For the price, the Zenfone 2 is pretty unbeatable. © ANDROIDPIT

ASUS Zenfone 2 technical specifications

    • Type:
    • Phone
    • Model:
    • ZE551ML
    • Manufacturer:
    • Asus
    • Dimensions:
    • 152.5 x 77.2 x 10.9 mm (ZE551ML, ZE550ML)
      148.1 x 71.5 x 10.9 mm (ZE500CL)
    • Weight:
    • 170 g (ZE551ML, ZE550ML)
      155 g (ZE500CL)
    • Battery size:
    • 3000 mAh (ZE551ML, ZE550ML)
      2500 mAh (ZE500CL)
    • Screen size:
    • 5.5 in (ZE551ML, ZE550ML)
      5 in (ZE500CL)
    • Display technology:
    • LCD
    • Screen:
    • 1920 x 1080 pixels (0 ppi) (ZE551ML)
      1280 x 720 pixels (0 ppi) (ZE500CL, ZE550ML)
    • Front camera:
    • 5 megapixels (ZE551ML, ZE550ML)
      2 megapixels (ZE500CL)
    • Rear camera:
    • 13 megapixels (ZE551ML, ZE550ML)
      8 megapixels (ZE500CL)
    • Flashlight:
    • Dual-LED
    • Android version:
    • 5.0 - Lollipop
    • RAM:
    • 4 GB (ZE551ML)
      2 GB (ZE500CL, ZE550ML)
    • Internal storage:
    • 32 GB (ZE551ML)
      16 GB (ZE500CL, ZE551ML)
      128 GB (ZE550ML)
    • Removable storage:
    • microSD
    • Chipset:
    • Intel Atom
    • Number of cores:
    • 4
    • Max. clock speed:
    • 2.3 GHz (ZE551ML)
      1.6 GHz (ZE500CL)
      1.8 GHz (ZE550ML)
    • Connectivity:
    • HSPA, LTE, NFC, Dual-SIM , Bluetooth 4.0

Final verdict

Asus has really outdone itself here: it has managed to produce a premium-looking device in the same design class as the HTC One (M8) and the LG G3 at the same time as putting the world’s first 64-bit chip in combination with 4 GB of RAM.

But the real feather in the cap is the price, which is incredibly low. Sure, the rest of the specs sheet of the Zenfone 2 may not be quite as impressive as some of the other flagships we've seen this year, but again: look at that price. For a phone this cheap you’re not going to find anything comparable (until the OnePlus Two appears perhaps).

With impressive devices like the Zenfone 2 and the always-low Asus pricing structure, the company is making great inroads. To sum up the Zenfone 2 you've got a great-looking device with a solid camera and battery, fun and customizable interface and serious multitasking and graphics capabilities. The raw processing power may not be up there with high-end flagships, but for the price the Zenfone 2 is pretty unbeatable. 


Write new comment:
  • What? I got 63440 score in antutu and the best part is that I bought it on a sale for 190 dollars

  • The chip used in the ZF2 (Intel Atom Z3580/Z3560) is just as near as many high end chips. It beats some other chips like the Snapdragon 801, Exynos 7578 and the Apple A7

  • Kris, hi. I was wondering, is it generally true that smartphone batteries will, after a year or two, start to lose the ability to hold charge to the point of making a battery replacement a necessity? If true and it applies to the ZF2, how long do you think the built-in battery in said phone will fare after appx' 3 years of daily use/recharging? Would it need replacing?

    I'm very uneasy about the battery in the ZF2 only lasting (less than) 3 years as I am particularly unable to afford a new phone as frequently as that; batteries on the other hand, are (generally speaking ) not a problem.

    My current phone, (a Star Note 9770), the first battery only lasted about 18mths, I'm on the second battery now. I fear the prospect of having to buy a new PHONE when the battery in the ZF2 starts to become less able to hold its charge.

    I have heard that replacement batteries for the ZF2 CAN (currently, late Sept' 2015) be bought from stores in the far east, but only for trade, not consumer; I'd hope there would be batteries available to consumers like myself, (in the UK), to replace a dying/dead one in the Asus beast; what do you think?

    Please advise. Thank you.

    • Considering the price of other phones, I doubt affordability should even be an issue. That said, I have an ASUS Zenfone 6, and I got the Zenfone 2 six months after, both phones batteries have not shown any degradation. The battery on the Zenfone 2 can be removed by simply unscrewing the 12 screws on the protective plate with a small Phillips screwdriver. The actual battery can be purchased on eBay, if in fact something happens to it. Also note, the device comes with a one year manufacturer's warranty. So you should be worry-free for a year. Hope that answers your question.

    • Hey man, I currently own Zenfone 2 ZE551ML 4GB RAM 2.3Ghz 32GB. And I'm like you I keep my phone for kinda long time because I can't afford replacing a phone every 1-2 years like most people in US and UK do (I'm not from Neither but still). That is true that batteries REDUCE charge after few years but I really doubt it will completely die in 3 years it will drain quicker but it will charge and when it does I'm sure there will be replacement batteries in fact there already are but they are not very cheap. And plus Zenfone 2 is not very hard to disassemble like Sony, Apple and other most phones. I always search parts and stuff like that on Ebay but search well because there are a lot of scammers there. Check for ratings and feedback. Hope this helped mate.
      P.S You said you have Star Note 9770 I have to heard Star brand anywhere it must be a Chinese cheap manufacturer please stay away from phone like that. Buy from a know brand. Asus, Sony, Samsung, Apple, HTC, Microsoft...

  • How would this compare to the Asus Zenfone 2 in terms of overall responsiveness, battery life, and the camera? I have the 4GB version.

    • For me, battery life is pretty much average but it is a software issue. ASUS is working on a fix so probably when marshmallow comes out on the ZF2, battery life will be better. Responsiveness is great and camera is good for the most part.

  • "the processor is nowehre near as powerful as many other high-end chips."

    Nowhere Near? Tell us about all the "many" high-end chips that are faster! The Intel Atom Z3580 is faster than the Apple A8 and the snapdragon 810, without the overheating issues. Nowhere Near, Indeed...

  • plck74 May 19, 2015 Link to comment

    can review on battery and 3d games? let us know once done. lol

  • tej das May 18, 2015 Link to comment

    well to tell you the truth, the battery backup on zenfone sucks. I'm using Zenphone 5 and battery drains at about 1% every 3 minute. Same is the condition with zenfone 2 as a friend of mine owns one

    • If you go to the battery section in the settings menu on the ZF2, you will see that the thing that's draining the battery is AndroidOS. It is a software problem so Asus is working on a fix.

  • This phone has higher specs than the iphone 6, the galaxy s5 and the lg g3 and you call it mid range? I think that this is a high end phone.

  • At last, a phone manufacturer that doesn't feel compelled to cram a 2k screen on a smartphone. After owning the LG G3, it will be a very long time before I buy another Android handset with a 2k screen. Personally, I prefer performance over ridiculously high PPIs. Will be buying this phone the moment it's available in the UK. Nice work Asus.

    • Don't let the bad performance on the G3 due to its high resolution display keep you from buying others with them, the Galaxy Note 4 and Galaxy S6 I have run beautifully especially the S6 which I've seen no performance issues with at all, I mean not a single single issue. LG has gone the way that Samsung use to just cramming as much crap as they can into their experience and performance suffers like we use to see from TouchWiz, IT'Z Samsung has really dialed it back with the fluff and it's got the second best running device now with the S6 just behind the HTC M8/M9 experience which performs as good as it gets.

  • CJ Brown Jan 19, 2015 Link to comment

    Nice Device
    Proof that brand name co's need to think about the price a competitor is offering because that is now the 'game changer' (won't pay $700 for a Samsung, will pay $300 for this Zenfone) :)

  • OK the cons are a bit weird. Midrange with 4GB RAM? And capacitive buttons are not really a con, more of a personal preference.

  • I'm liking what I'm seeing and hope I can purchase this device upon release!

  • PC0 Jan 9, 2015 Link to comment

    "The presence of this hardware package should make short change of all but the most demanding processes." I think the expression you were looking for was "make short work of."

    • Ha, thanks! It had been a long day.

      • Long enough perhaps that it isn't the only error you made?

        "On the front you’ve got the unfortunate addition of capacitive buttons, hosted in a black band like the HTC One (M8) which I’m personally not a fan of, but you’ve got a nice big 5.5-inch screen regardless."

        The M8 doesn't have capacitive off-screen buttons like this device does. The M7 did/does. The M8 has standard on-screen software buttons. They're only in a black bar some of the time when on screen and sometimes on a transparent bar or a lightly tinted bar, exactly as Google intended. It's an easy enough mistake to make if you haven't actually used an M8.

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