Xiaomi Mi 4s review: Pushing forward

Display

The Xiaomi Mi 4s features a similar 5" Full HD IPS display to the one we saw on the Mi 4c. It has 441ppi for pleasantly sharp screen contents. Xiaomi says both sheets of glass on the Mi 4s are scratch resistant without specifying their brand or maker.

Taking a closer look at the display under our digital microscope reveals a standard RGB arrangement of the sub-pixels that make up the Xiaomi Mi 4s LCD panel.

The maximum display brightness of the Xiaomi Mi 4s (475nits) won't turn any heads, nor will the average contrast ratio of 975:1. The blacks are deep enough for an otherwise pleasant viewing experience.

The minimum display brightness is incredibly low at 0.6nits, which is perfectly suitable for late-night reading in a dark setting.

Regarding color accuracy, the Mi 4s screen is less than stellar with an average deviation (DeltaE) of 5.6, which shows the screen has less than perfectly accurate color rendering. We've seen worse even in flagship devices, so this one sits somewhere in the middle. For a screen to be considered properly calibrated it needs to have a maximum DeltaE of 4 and obviously, the lower the deviation, the better.

The sunlight legibility of the screen is hardly spectacular, but you won't have any problems using the phone outdoors if you avoid direct sunlight.

Sunlight contrast ratio

• Samsung Galaxy S6 edge+
  4.615
• Samsung Galaxy S7 edge
  4.439
• Samsung Galaxy S7
  4.376
• HTC One A9
  4.274
• Samsung Galaxy A3
  4.241
• Samsung Galaxy S6 edge
  4.124
• Samsung Galaxy Note5
  4.09
• Huawei Nexus 6P
  4.019
• OnePlus X
  3.983
• Oppo R7s
  3.964
• Samsung Galaxy A7 (2016)
  3.918
• Samsung Galaxy A5
  3.895
• Samsung Galaxy J7 outdoor
  3.879
• Samsung Galaxy J2 outdoor
  3.873
• Samsung Galaxy A8
  3.859
• Apple iPhone 6
  3.838
• Microsoft Lumia 950XL
  3.837
• Samsung Galaxy A9 (2016)
  3.817
• Motorola Moto X (2014)
  3.816
• Samsung Galaxy A5 (2016)
  3.789
• Apple iPhone 6s
  3.783
• Meizu Pro 5
  3.781
• Vivo X5Pro
  3.706
• Samsung Galaxy A7
  3.679
• BlackBerry Priv
  3.645
• Apple iPhone 6s Plus
  3.53
• Microsoft Lumia 950
  3.512
• Oppo R7 Plus
  3.499
• Samsung Galaxy J7
  3.422
• Meizu MX5
  3.416
• Oppo R7
  3.32
• Xiaomi Mi 5
  3.24
• Samsung Galaxy J2
  3.235
• Motorola Moto X Play
  3.222
• Lenovo Vibe Shot
  3.113
• LG Nexus 5X
  3.092
• Huawei Mate S
  3.073
• Microsoft Lumia 640 XL
  3.065
• Apple iPhone 6 Plus
  3.023
• Samsung Galaxy Note
  2.97
• Huawei Mate 8
  2.949
• HTC One S
  2.901
• Sony Xperia Z5
  2.876
• Microsoft Lumia 550
  2.851
• Sony Xperia Z5 compact
  2.784
• LG V10
  2.744
• Xiaomi Redmi 3
  2.735
• Sony Xperia M5
  2.69
• Xiaomi Mi 4i
  2.641
• Xiaomi Mi 4c
  2.574
• Microsoft Lumia 640
  2.563
• Motorola Moto G 4G
  2.546
• Oppo F1
  2.528
• Sony Xperia Z5 Premium
  2.525
• HTC One
  2.504
• Sony Xperia M4 Aqua
  2.503
• Motorola Moto G
  2.477
• Huawei G8
  2.471
• Sony Xperia Z
  2.462
• Huawei Honor 7
  2.406
• ZUK Z1 by Lenovo
  2.382
• HTC One E9+
  2.305
• Lenovo Vibe K4 Note
  2.254
• Sony Xperia C5 Ultra
  2.253
• Xiaomi Redmi Note 3 (MediaTek)
  2.249
• Sony Xperia C4 Dual
  2.235
• Motorola Moto G (2014)
  2.233
• LG Nexus 5
  2.228
• Huawei P8
  2.196
• Xiaomi Redmi Note 2
  2.166
• HTC One X
  2.158
• LG Aka
  2.145
• Archos 50 Diamond
  2.134
• Xiaomi Redmi Note
  2.119
• Xiaomi Mi 4S
  2.095
• Huawei P8lite
  2.078
• Moto G 3rd gen max manual
  2.026
• Sony Xperia E4g
  1.972
• Meizu m2 note
  1.892
• BlackBerry Leap
  1.892
• HTC Butterfly
  1.873
• ZTE Nubia Z9 mini
  1.759
• Sony Xperia U
  1.758
• Asus Zenfone Selfie
  1.68
• Motorola Moto E (2nd Gen)
  1.675
• ZTE Nubia Z9
  1.659
• Motorola Moto E
  1.545
• Sony Xperia M
  1.473
• Xiaomi Redmi 2
  1.311
• Sony Xperia C
  1.283
• Meizu MX
  1.221

Battery life

Xiaomi has put a 3,260mAh battery inside the Mi 4s, a solid capacity for a 5" device. In our battery test, the Xiaomi Mi 4s scored a 75h rating, which means you can count on a little over three days if you do an hour each of calling, browsing and video playback a day. The phone did well in all three of our individual tests and it had a low battery draw in standby as well.

Opting for using the device with two SIM cards will clip some four hours off the total endurance rating.

That is of course solely based on the two SIMs drawing battery in standby - using an estimated power usage to make our battery results comparable across devices.

Xiaomi is providing a proper fast charger (5V/2A, 9V/1.2A, 12V/1A) in the retail box, which is nice. In our 30-minute charging test, the provided charger was able to charge the battery of the phone from 0% to 32%.

The battery testing procedure is described in detail in case you're interested in the nitty-gritties. You can also check out our complete battery test table, where you can see how all of the smartphones we've tested will compare under your own typical use.

Connectivity

The Xiaomi Mi 4s supports 7 LTE bands (the Europe's most common FDD LTE band 20 800MHz is missing though), and you can tap to an LTE network on either SIM, but the other will default to a GSM band. The Mi 4s also offers quad-band GSM connectivity and tri-band 3G connectivity with HSPA support.

The rest of the wireless connectivity features include dual-band Wi-Fi a/b/g/n/ac support and Wi-Fi Direct. There is also support for Bluetooth 4.1, GPS and GLONASS. Wireless screen mirroring is available via the Miracast protocol.

The IR blaster is located at the top and, coupled with the right software, you can use it to remotely control pretty much any IR controlled home appliance. Xiaomi provides its own MiRemote app, which supports a long list of devices right out of the box.

The Mi 4s is Xiaomi's third device to support USB Type-C - it's the new reversible connector for USB that builds on USB 3.1.

If you'd like to use USB OTG functions on the Mi 4s, you'll have to buy a third-party USB OTG adapter.