The Redmi 4 Prime redefines what a budget display is these days. A 5-inch FullHD panel with a pixel density of 441ppi in a phone that goes for $130 in its home country? Sure, why not.
The maximum brightness is about average for the Redmi range - on par with the Redmi 3, lower than the Redmi 3 Pro, and higher than the 3S. The Sony Xperia E5 is capable of a few more nits, but overall the Redmi 4 Prime is plenty bright. Maximum brightness is slightly lower in Auto mode.
Blacks aren't spectacularly deep but are still reasonably well contained, making for a contrast ratio well exceeding 1000:1 - above 1100:1, actually. The excellent minimum brightness of 1.2nits ensures comfortable night scrolling sessions.
|Display test||100% brightness|
|Black, cd/m2||White, cd/m2|
Colors are reasonably accurate in Standard/Standard mode (there are separate settings for 'saturation' and 'colors') with an average DeltaE of 4.6 - a step in the right direction from the Redmi 3S (5.5) and Redmi 3 Pro (6.4). Standard Warm takes average DeltaE to 4.4, and that's the most accurate mode overall. The default mode out of the box is Brilliant for saturation and Standard for colors - an average DeltaE is 5.0.
Sunlight legibility isn't great, but the Redmi 4 Prime is still capable of achieving decent contrast - for an LCD, that is.
The Xiaomi Redmi 4 Prime supports 7 LTE bands, much like previous Redmis, and which SIM gets to connect to a 4G network is selected in settings - the second one, if there is any, gets 3G or 2G connectivity. You can even have both registered on 3G networks, when 4G is not available.
The rest of the connectivity features include dual-band Wi-Fi a/b/g/n support and Wi-Fi Direct. There is also support for Bluetooth 4.2, GPS with GLONASS and Beidou, plus an FM radio.
A microUSB 2.0 port handles charging and data connections. Media transfer mode is supported for accessing the phone's built-in memory over a USB connection. The microUSB port also supports USB On-the-go for connecting USB peripherals such as pen drives, keyboards or USB hard drives.
Wireless screen mirroring is available via the Miracast protocol.
The IR blaster is located on the top and coupled with the right software, it can be used to operate almost any remotely controlled home appliance, turning the Xiaomi Redmi 4 Prime into a universal remote. Xiaomi provides its MiRemote app right out of the box.
The Redmi 4 Prime draws power from a 4,100mAh battery - introduced with the original Redmi 3 in January this year, that's been the capacity of 4 other different Redmi Threes, and the 3 Redmi Fours announced so far (we bet there'll be more).
That's a whole lot of juice for a 5-incher, but this one here is the first of the small Redmis with a FullHD display as opposed to 720p. Then again, the Redmi 4 Prime's chipset should be the most efficient one to date, as it's built on a 14nm process. Let's see.
Starting off with talk time, the Redmi 4 Prime will happily last over 29 hours on a 3G call. More impressively, though, it can also do 20 full hours of web browsing over Wi-Fi with the display set to 200nits. Video playback endurance isn't as spectacular, but the phone still averaged about 10 hours on the task.
All that adds up to an endurance rating of 91 hours - not quite a match for the Redmi 3S we last reviewed but an excellent performance nonetheless.
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.