Xiaomi MIX 4 Review: Not Only A True Full-Screen Phone

On October 25 in 2016, Xiaomi launched a phone dubbed the Xiaomi Mi MIX, which started a new era of full-screen smartphones. This handset was using three narrow screen borders and the front camera placed on the chin. Many were thinking that this is a concept phone and will never become a final product. But at the same conference, Xiaomi said it is going to pre-order.

Since then, full-screen solutions have emerged one after another. Even when the iPhone X came with a notch design, many were thinking that this was the first full-screen smartphone. But those who have been following news concerning this niche never forgot the founding father of the new design.

After that, the appearance of each generation of MIX almost represents a new trend in the development of full-screen mobile phones. And of course, they not only include the screen, but also various hardware design iterations of the mobile phone from the inside to the outside.

The last attempt – the Xiaomi MIX 3 – disappointed many customers. Of course, it was a true full-screen smartphone. But for this, the phone was using a sliding structure

Anyway, since the MIX 3, this series has fallen into coma. After three years, the manufacturer could bring a new generation powered by a number of innovations including a Camera Under Panel (CUP).

Xiaomi MIX 4 Design

The packaging box of the Xiaomi MIX 4 is not “environmentally friendly” at all. It is much larger than the average mobile phone case, and the content is also very rich, ranging from protective cases to chargers.

The style of the packaging box also uses a classic MIX style.

When taking the phone out from the box, we can see a true full-screen with no openings.

To ensure a sufficient light passing through the screen, the front camera area uses a special diamond arrangement technology. So under a strong light and at a certain angle, you can vaguely see the sensor under the screen. In addition, unlike the square-shaped under-screen area solution previously seen, the under-screen camera module of the Xiaomi MIX 4 is closer to the original “punch” style.

At the top of the screen, you can also see the earpiece with a micro-slit design, which supports external sound and can provide a certain dual-speaker stereo effect.

The edge of the screen uses the latest micro-curved design.

The back camera design of the Mi MIX 4 is similar to the family design of this year’s Mi 11 series. It also uses a rectangular camera module, plus decorative elements of left and right color separation. In addition, the back cover adopts lightweight integrated precision ceramics.

The rear camera module includes a 100MP main sensor, an 8MP 5x telephoto lens and a 13MP wide-angle lens.

A microphone opening is on the upper and lower sides, while the Type-C interface is on the bottom. There is also an infrared module on the top and dual speakers certified by Harman Kardon.

The SIM card slot is also at the bottom.

The 120W charger that comes with the package is not small. The Xiaomi MIX 4 supports a 120W wired charging  as well as a 50W wireless charging. But there is also a faster speed mode, which is the top speed in the current fast charging of mobile phones.

Under-Screen Camera

The under-screen camera changes the shape and arrangement of pixels, but the overall pixel density (PPI) will not be greatly reduced. So when looking at the screen with naked eyes, users won’t see the front camera.

Currently, there are 3-4 under-screen camera smartphones – ZTE Axon 20 /30, Samsung Galaxy Z Fold 3 and the Xiaomi MIX 4. The micro-diamond arrangement adopted by the Xiaomi MIX 4 is the one with the most delicate display effect.

Xiaomi MIX 4

As we all know, OLED screens will cause a certain degree of resolution loss due to the difference in pixel arrangement (compared to native LCD). And because of technical limitations, the current resolution of the under-screen proactive screen can only achieve 1080P.

In addition, in the front camera area, the Xiaomi MIX 4 also uses the same micro-diamond arrangement, but the red pixels are changed into circles, and the overall pixel size is further reduced.

The photo effect of the off-screen front camera is closely related to the light transmittance. Therefore, although the Xiaomi MIX 4 is the best off-screen camera phone, the self-portrait effect may appear slightly worse.


The Xiaomi MIX 4 is the first to come with the Snapdragon 888 Plus processor. Compared with its predecessors, it has mainly two improvements. The frequency of the super large core has been increased to 3.0GHz. In addition, the AI ​​performance has also been greatly improved, and the computing power has soared to 32TOPS, an increase of up to 20%.

Master Lu

Master Lu’s running score was as high as 892,426 points, surpassing 99% of other phones and ranking 4, which shows that the performance of Snapdragon 888 Plus is still quite impressive. With the performance advantage of the super-large core, the Mi MIX 4 can easily be compared with a lot of gaming phones.


In AnTuTu, it scored 819,261, which exceeded 98% of other phones.


The MIX 4 comes with a UFS 3.1 flash storage with a continuous read speed of 1724.1MB/s and a continuous write speed of 741.62 MB/s.


The Snapdragon 888 Plus has a single-core performance of 1125 points and a multi-core performance of 3405 points.

For reference, the Xiaomi Mi 11 Pro has a single-core performance of 1010 and a multi-core performance of 3132 at room temperature. Simply put, the performance increase in the daily environment is about 10%.


The GPU part of the Snapdragon 888 Plus does not have any enhancements. You can compare the heat dissipation of different models according to the GPU running points.

Overall, the GFXbench score of the MIX 4 is even higher than that of the Mi 11 Pro by about 4%. We can see that the heat dissipation design of the MIX 4 is probably better than Mi 11 Pro.

In terms of games, we selected four games for testing. The screen settings are all with the highest picture quality at the highest frame rate. Basically, all games performed very well.

In general, the enhancement of the Snapdragon 880 Plus is limited. Although the super-large core frequency has been enhanced and AI performance has improved, its overall performance is still not much different from the familiar Snapdragon 888.


The Xiaomi MIX 4 features a 100-megapixel main camera. This is the same HMX sensor that Xiaomi has tuned for multiple generations. In addition, there are 12-megapixel free-form wide-angle lens and 5x telephoto lens.

As said, the main sensor can be found on multiple Xiaomi phones. Since the Xiaomi CC9 Pro, this CMOS has been optimized for nearly two years.

Xiaomi MIX 4

Its biggest feature is its extremely high resolution. It can clearly record the details of distant buildings and green plants when taking pictures in the daytime when the light is good.

In low-light environments, HMX focuses on highlighting the texture of night lights and the atmosphere at night. As long as there are bright lights in the picture, the polar night algorithm will not be triggered, and the brightness can be increased violently, which can greatly highlight the tranquility of the night.

For ordinary users, compared to the 24-27 equivalent focal length of the main camera, which requires repeated movement to compose the picture, telephoto does the job more easily.

The MIX 4 uses a free-form surface lens, which can greatly reduce the edge distortion under the wide-angle and improve the image quality of the corners. When actually taking pictures, the wide-angle lens can accommodate more scenes, and the addition of the free-form surface lens greatly reduces the corner distortion.

Battery And Charging

The Xiaomi MIX 4 comes with a 4500mAh battery, which also supports 120W wired charging and 50W wireless charging. And not only fast, it also provides many customization options for charging. For example, you can choose whether to turn on fast charge acceleration. After turning on, the charging speed will be maximized, but the temperature will not be controlled.

When testing the 120W wired charging, from 4% to 100%, it only takes 19 minutes. If the heat dissipation conditions are good, the charging speed will be faster, and it only takes 10 minutes to charge 80% of the power.

Xiaomi MIX 4

The default power of wireless charging is 50W, and it takes 40 minutes to reach 100%. In the phone settings, there is also an option for fast charging. The wireless charging speed will be further improved after it is turned on. The total time is only about 24 minutes.

In terms of battery life, under the +120Hz refresh rate in the balanced mode, the Xiaomi MIX 4 consumes 15% of power in one hour in a comprehensive use scenario of web browsing, video, and games. So we guess it will last for 6.7 hours.


Every time a new MIX is released, there are many surprises, and the MIX 4 is no exception. If you are an old fan who has been waiting for the MIX series to update, then please rest assured that the MIX 4 is definitely a qualified MIX orthodox sequel. It still adheres to the MIX series’ pursuit of the most cutting-edge technology, the best under-screen front camera, Snapdragon 888 Plus, full focal range rear camera, dual-height fast charging, and the persistence of the ceramic back cover.

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