Xiaomi MI 9 Specifications, Tests and Review

Design of Xiaomi MI 9 has dimensions of 157.5 mm × 74.67 mm × 7.61 mm and weight of 173 g.

The screen size reaches 6.39" inches. With a large display, phone offers a great experience for watching videos, playing games and reading. The best phones today are 6.5'' or more. They have the advantage of a large display area that allows you to see more content than with conventional display sizes. Owing to OLED technology, the display offers a true representation of colours, especially black. The resulting contrast is significantly higher and colours appear more vivid. OLED technology is now part of most smartphones, while LCD displays are becoming a thing of the past in mobile phones. OLED displays also have lower power consumption compared to LCD technology.

Display Resolution of Xiaomi MI 9 is 2340 x 1080 pixels. A higher display resolution is a prerequisite for a sharper image. The standard for mid-range phones today is a Full HD resolution of 1920 × 1080 px. Cheaper phones, which usually have a smaller diagonal, have an HD resolution of 1280 × 720 px. Smaller resolutions can only be found in older models. Best phones, on the other hand, have a 4K resolution of 3840 x 2160 px. If you want a perfect picture, focus on pixel density in addition to resolution. This number indicates how sharp the image will be. Best phones today have a display fineness of 450 ppi or higher, but the today´s average is around 350-400 ppi. That should be enough for you to enjoy a fine and sharp image. This model has a pixel density of 403 ppi.

The processor type of the Xiaomi MI 9 is Qualcomm Snapdragon 855. The number of processor cores is 8. It is a number of cores that plays an important role in evaluating the performance of phone as it is responsible for computing operations. Smartphones already commonly have a core count of around 4 to 8. Multi-core processors can perform better and reduce the processing time of a request to a minimum, which is reflected in the responsiveness of the phone, e.g. in the speed of opening applications. Xiaomi MI 9 is provided with processor´s frequency of 2.84 GHz. Normally today you will find this value between 1.8 and 2.8 GHz, and the higher the number, the faster the response of the phone. The processor frequency will thus be one of the important parameters if you are looking for a phone capable of managing several requests at once without major problems.

The processor also includes the graphics accelerator Qualcomm ADRENO 640.

The phone is provided with an internal memory of 64 GB. Internal storage capacity is often a key parameter, as it determines how many files, photos, apps and more your phone can store. If you expect to store low thousands of photos, some songs, few movies or games on your phone, then you can easily get by with a medium memory size. Phones with this size of memory also has the advantage of a lower purchase price. If you don't plan to use your phone for 4K video creation and storage, using hundreds of apps etc. then you should feel free to go with this memory size. Fortunately, manufacturers nowadays think of all users and therefore offer phone models with different memory sizes so that everyone can choose what suits them.

Operating memory significantly affects the performance of the entire phone. Xiaomi MI 9 has an operating memory of LPDDR4X SDRAM - 6 GB. Phones with less than 4 GB of RAM are better suited for undemanding users who use phone more for basic needs and some essential applications only. But if you are a heavy user, reach for at least 6 to 8 GB of RAM, which is the standard today, or 12 GB for the really demanding ones.

The rear camera of the Xiaomi MI 9 is equipped with 3 lenses. A larger number of lenses usually results in better quality photo, as each lens is designed differently: usually as a macro lens, telephoto lens or wide-angle lens. Macro lens is used for great close-ups, telephoto lens is designed for capturing objects in the distance as it often has an optical zoom, and wide-angle lens will take great landscape photos where you need a larger field of view. The main lens is designed as Ultra wide-angle lens. A high resolution lens alone does not necessarily mean high quality photos. The main lens in this has a resolution of 48 Megapixel. However, if you are looking for perfect photos, in addition to resolution, don't forget to focus on at other parameters such as lens aperture or pixel size. Pixel size is typically around 0.8-1.8 μm in better mobile phones. The higher the value, the better the quality of the resulting photo should be. In the case of main lens, the pixel size reaches 0.8 μm. Luminance is one of the main factors determining the quality of a photograph. Commonly today, this value ranges between F/1.8 and F/2.2. However, best photomobiles have an aperture of up to F/1.2. Value indicates how much light passes through the sensor and the lower it is, the better the quality of the photos. Main lens here is equipped with F/1.75.

Digital zoom in this case offers zooming up to 10x. Of course, the higher the lens value, the more distant object can be zoomed in. Nonetheless, the disadvantage of digital zoom is that the quality and sharpness of photo deteriorates when using it. Much more important is the optical zoom, which has the advantage of not losing quality and sharpness when zooming in. On this phone, the optical zoom is 2x. If you like to take photos of people and portraits, you'll appreciate the facial recognition feature. The camera automatically detects face and focuses on it.

Second camera
The second lens of rear camera is designed as Telephoto lens. The resolution reaches size of 12 Megapixel. Pixel size in this case is 1 μm. Furthermore, aperture of second lens reaches size of F/2.2.

Third camera
Lens number three represents the Ultra wide-angle lens. The resolution of third lens is then 16 Megapixel. The pixel size that significantly affects quality of photo is 1 μm. Finally, the lens also features a lens aperture of F/2.2.

Front camera
The front camera of phone Xiaomi MI 9 has one lens. This number of lenses is standard on most smartphones nowadays. The resolution of main lens reaches 20 Megapixel. Again, it should be noted that resolution is not the only factor affecting the quality of the front camera photo. The pixel size itself is 0.9 μm. The aperture of main lens is F/2.0.

The facial recognition feature is just a nice cherry on top.

The battery size of Xiaomi MI 9 is 3300 mAh. Nevertheless, battery capacity is not the only factor that affects the phone's battery life. For example - the size of the display, the performance of the processor, the use of data functions and, of course, the intensity of use of phone in general all have a significant impact on battery life. Standard for most smartphones today is a battery capacity of around 4500 to 5000 mAH. Phones with this battery size usually guarantee a phone life of at least 1 day. Older or cheaper smartphone models can then reach battery capacities typically around 2500 mAH and below. With this capacity, you may find that if you use your phone heavily, you may need to recharge your phone during the day. The fast charging function will also please many people. Owing to fast charging, phone charges up to several times faster, which you will appreciate, for example, on the go.

Xiaomi MI 9 supports 4G. 4G connectivity is still common today, although the latest phones already have 5G connectivity. 3G connectivity is now more of a thing of past and can only be found on older models. This model also offers ability to pay by phone with Android Pay.

The NFC function will please all fans of contactless mobile payments. In addition, you can also use function in the context of connectivity, for example, to unlock doors or load menus in restaurants. Bluetooth 5.0 makes it easy to connect your phone to other wireless devices such as headphones, speakers, TV or tablet and more.