The Xiaomi Mi 9 lineup, launched in 2019, has become one of the company’s most successful smartphone series. Three models — the Mi 9, Mi 9T (also known as the Redmi K20 in China) and Mi 9 SE — offered different approaches to the flagship experience, from compact design to retractable selfie camera. Today, 5 years later, these devices remain relevant in the used market, but their differences often cause confusion. What is the fundamental difference between the models?
In this article, we will make an in-depth comparison of 12 key parameters, from processors and screens to software features and maintainability. You will learn why the Mi 9T became a cult among media enthusiasts, what the Mi 9 SE surprises in 2026, and what hidden problems can await buyers of used versions. And for those who are planning to buy, we have prepared a checklist for the checklist of the device before the deal.
1. Design and Ergonomics: Compact vs Innovation
Externally, all three models belong to the same family, but the design approaches are radically different. Xiaomi Mi 9 and Mi 9 SE use the classic layout with a cutout in the screen ("monobrov"), while the Mi 9T became the first mass-produced smartphone of the brand with a full-screen display thanks to a retractable front camera, which achieved a screen-to-body ratio of 91.9% – a record for 2019.
The dimensions of the models demonstrate different philosophies:
- 📏 Mi 9 SE: 147.5×70.5×7.5 mm, 155 D - the most compact and lightweight, comfortable for one hand
- 📱 Mi 9: 157.5×74.7×7.6 mm, 173 d - "Golden mean" with a premium glass case
- 🖥️ Mi 9T: 156.7×74.3×8.8 mm, 191 d is the most massive because of the retractable mechanism
It is important to note that Mi 9T It has a metal frame, while the Mi 9 and SE It's plastic metal. It affects the sense of touch and strength. 9T There's less backlashes when you press the screen, but it's heavier. SE stand out 3D-Gorilla Glass 5 on the back, which resists scratches better than older models.
⚠️ Attention: Retractable mechanism Mi 9T It has a limited resource of about 300,000 cycles (according to Xiaomi).When buying used, check the smoothness of the camera and the presence of extraneous sounds.
2.Screens: AMOLED vs Super AMOLED and refresh rate
All three models are equipped with AMOLED-matrixes, but with key differences in technology and characteristics. Mi 9 and Mi 9T use Super AMOLED from Samsung with support for HDR10, while Mi 9 SE received a more budget AMOLED from BOE. The difference is noticeable in color reproduction: the SE-version of the colors are cooler out of the box, and the maximum brightness is lower by ~15%.
| Parameter | Mi 9 | Mi 9T | Mi 9 SE |
|---|---|---|---|
| Diagonal | 6.39" | 6.39" | 5.97" |
| Permission | 2340×1080 | 2340×1080 | 2340×1080 |
| Type of matrix | Super AMOLED | Super AMOLED | AMOLED |
| Frequency of update | 60 Hz | 60 Hz | 60 Hz |
| Support for Always-On | Yes. | Yes. | No. |
The key difference is the Mi 9T — No physical fingerprint sensor, instead using an optical scanner under the screen that is slower than the traditional one (the difference in unlock speed). ~0.3 sec. But this model has DC-dimming to reduce screen flickering at low brightness, which is important for eye-sensitive users.
The Mi 9 SE is not only smaller than the older brothers, but also functionally, with no Always-On Display support or automatic color temperature control, but it has the highest ppi (432), thanks to its compact diagonal, which makes the image more detailed.
3.Performance: Snapdragon 730 vs 855 and overheating issues
The differences are most significant here: Xiaomi Mi 9 and Mi 9T use Qualcomm’s flagship Snapdragon 855 chips, while Mi 9 SE received a Snapdragon 712 – top-to-middle processor. The difference in performance is 40-50% in synthetic tests and 20-30% in real tasks (for example, video rendering or high-setting games).
However, there is a nuance: Mi 9T in some regions sold with the Snapdragon 730 (modification of the Mi 9T Pro received 855th). This is important to consider when buying used! Check the model of the processor can be in Settings → About phone → MIUI version, tapping several times on the "CPU core".
- 🎮 For gamers: Mi 9 with Game Turbo 2.0 and liquid cooling system better suited for long sessions
- 📸 For photographers: Mi 9T It has better camera optimization thanks to a separate camera ISP Snapdragon 855
- 💰 Budget option: Mi 9 SE They are able to cope with everyday tasks, but they are slowing down in multitasking.
Critical problem of the Mi 9: the model is prone to overheating under intense loads due to the compact body. Temperature can reach 45-47 ° C in games, which leads to trottling (automatic performance decline). In the Mi 9T, this problem is solved by a more massive body and improved cooling system.
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Before buying a used Mi 9, check the thermal paste condition - its drying worsens cooling. Signs: the phone heats up quickly even on simple tasks.
4.Cameras: basic module vs telephoto vs ultra-wide angle
The camera system is one of the main differences of the models. Xiaomi Mi 9 received a triple module with the main sensor Sony IMX586 48 MP, telephoto 12 MP (2x zoom) and a wide-angle 16 MP. Mi 9T retained the same main camera, but replaced the telephoto with a macro lens 2 MP and added a depth sensor 2 MP for portrait mode. Mi 9 SE cost a dual camera: 48 MP (IMX582) + 8 MP (wide-angle).
The real differences in the shooting:
- 🌃 Night shooting: Mi 9 and Mi 9T The same Night Mode 2.0 algorithm is available, but the Mi 9 is better at handling noise thanks to its telephoto module.
- 🔍 Zoom: Only Mi 9 supports 2x optical zoom; the Mi 9T and SE digitally
- 📸 Selfie: Mi 9T wins thanks to the 20 MP retractable camera with autofocus (Mi 9 and the other two). SE fixed-focus)
The Mi 9 SE uses the Sony IMX582 sensor instead of the IMX586, which gives ~10% worse detail in low light, but this model has a unique feature - shooting video at 960 fps (the older models have a maximum of 240 fps).
⚠️ Attention: Retractable camera Mi 9T It has no protection from dust and moisture, even if it is IP53 (Splash protection) sand ingress can cause the mechanism to fail.
5. Batteries and charging: Capacity vs speed
Here, the lead is clearly behind the Mi 9T with a battery of 4000 mAh – 25% more than the Mi 9 (3300 mAh) and 43% more than the Mi 9 SE (3,070 mAh).
- 🔋 Mi 9T: 7-8 screen-clock
- 🔋 Mi 9: 5-6 screen-clock
- 🔋 Mi 9 SE: 4-5 screen-clock
However, the charging speed of the Mi 9 is out of competition: it supports 27W fast charging (there is an 18W adapter included), while the Mi 9T and SE are limited to 18W. Important: to activate the maximum speed on the Mi 9 requires the original USB-C to USB-C cable - with the usual USB-A speed drops to 15W.
All models support Quick Charge 4+, but only the Mi 9 has wireless charging (20W) making it the only one in the series with Qi charging capability. However, in 2026, finding compatible accessories becomes more difficult as Xiaomi has stopped producing them.
Original power adapter included | Battery capacity ≥80% (checked through ##4636##) | No swelling | Charging up to 100% in ≤2 hours | No spontaneous reboots at low charge-->
6.Software: MIUI and Update Issues
All three models originally came with MIUI 10 based on Android 9 Pie, but the update story has been different:
- 📱 Mi 9 and Mi 9T received MIUI 14 (Android 12) - the latest official update
- 📱 Mi 9 SE stopped MIUI 13 (Android 11)
This means that the Mi 9 SE does not support modern features like Google Discover on the home screen or improved resolution management in Android 12+. Moreover, the lack of security updates after 2023 makes this model vulnerable to new threats.
There’s good news for enthusiasts: all three models support custom firmware (LineageOS, Pixel Experience). However, the Mi 9T has a nuance: due to the retractable camera, some builds may not work properly with the front module. Before firmware, be sure to check compatibility on the XDA Developers forums.
Fun fact: The Mi 9 was sold in China as the Mi 9 Transparent Edition with a transparent rear panel and 12 GB of RAM. These models have a unique bootloader, and their firmware requires special tools.
How to check the version of MIUI and the ability to unlock the bootloader
7 Repairability and common breakdowns
When buying a used device, it is important to consider the cost and complexity of repairs, according to service centers, the most vulnerable elements are:
| Model | Frequent breakdown | Average cost of repair (2026) | Difficulty (1-10) |
|---|---|---|---|
| Mi 9 | Burnout of the motherboard (due to overheating) | 8 000 — 12 000 ₽ | 9 |
| Mi 9T | Breakdown of the retractable chamber mechanism | 5 000 — 7 000 ₽ | 8 |
| Mi 9 SE | Detachment of the touchscreen plume | 3 000 — 4 500 ₽ | 6 |
Key points:
- 🔧 Mi 9: Most often suffers from corrosion of contacts due to moisture entering through the speakers. Check the lower speaker - wheezing or lack of sound may indicate this problem.
- 🔧 Mi 9T: The camera's mechanism is sensitive to impacts. Even after the plume has been replaced, it may require calibration of sensors.
- 🔧 Mi 9 SE: The most maintainable model thanks to its modular design, the screen and battery are replaced without being completely disassembled.
The unique problem with the Mi 9T is that when you change the screen, you often have problems with the black display (the grey veil effect), due to the incompatibility of the original and non-original matrices, the solution is to install a special patch in the service center.
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Before buying used, be sure to check the device for IMEI in settings (Settings → Phone → General Information). Lack of IMEI or status "Null" indicate software lock after the motherboard is repaired.
8 Which smartphone to choose in 2026: expert recommendations
The choice of the model depends on your priorities:
- 🎯 For photography and video: Xiaomi Mi 9 is the best balance of cameras and performance.Optical zoom and wireless charging make it the most versatile.
- 🎬 For multimedia and gaming: Mi 9T — big screen, powerful processor (in Pro version) and great autonomy. Perfect for watching movies and streaming.
- 💼 For everyday tasks: Mi 9 SE — It's compact, it's lightweight, it's cheapest to repair, it's good for those who appreciate the convenience of one hand.
Price segment in the used market (according to Yandex.Market, June 2026):
- 💰 Mi 9 SE: 6 000 — 9 000 ₽ (budget-high)
- 💰 Mi 9: 10 000 — 14 000 ₽ (Optimal Price/Quality Relationship)
- 💰 Mi 9T: 12 000 — 16 000 ₽ (Most expensive because of the retractable camera)
If you are considering buying, look for alternatives:
- 🆕 POCO F3 (2021) with Snapdragon 870 and 120Hz screen can be found at 15,000 – 18,000 ₽
- 🆕 Redmi Note 12 Pro+ (2023) with 200 MP camera and 5000 mAh battery – about 20 000 ₽
However, if you are interested in the Xiaomi ecosystem (compatibility with Mi Band, smart lamps, etc.), then the 9 Series remains a relevant choice thanks to the full support of Mi Home and Xiaomi Cloud.
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When buying a used Xiaomi smartphone, be sure to check the binding of the Mi Account. If the seller has not untied the device from his profile, you will not be able to use Xiaomi services (cloud, themes, updates).