Choosing a fitness tracker often becomes a difficult dilemma, especially when it comes to popular models from Xiaomi. At first glance, the Mi Band 4 and Mi Band 6 devices seem very similar: the same capsule form factor, similar strap design and an identical set of basic sports modes. However, on closer examination, it becomes clear that in the two years between the release of these gadgets, the company’s engineers made drastic changes in the “stuffing” and user experience.
Many users are still wondering whether it makes sense to overpay for a newer model or whether the budget four is still relevant in today’s world. The answer lies not only in the specifications, but also in how you plan to use the device. While some people only care about counting steps and notifications, others are critically needing advanced health monitoring features and a better display.
In this article, we will explore the key differences that affect everyday use, including screens, sensor accuracy, software and operating system compatibility, and understanding these nuances will help you make an informed purchase decision without overpaying for unnecessary features or saving on important functionality.
Design and design features of the buildings
Visually, the difference between the models is only noticeable when directly comparing side-by-side.The Xiaomi Mi Band 4 has retained the classic elongated capsule shape that has become the standard for the lineup.The body is made of matte plastic that collects little to no fingerprints, but tends to scratch quickly when used actively.
The Mi Band 6 has a redesigned, larger screen that takes up almost 70 percent of the front panel, and the tracker's dimensions have become a little wider, requiring engineers to redesign the straps, and now the mounts are deeper, and the straps themselves have become wider at the junction with the body.
⚠️ Note: The Mi Band 4 straps don't physically fit the Mi Band 6 and vice versa. The mount design has been changed, so when buying additional accessories, be sure to pay attention to compatibility with a particular model.
The weight of the devices is almost identical, about 20 grams without a strap. However, because of the increased screen area, the sixth version feels a little more massive on the hand. This is especially noticeable in thin winter sleeves or when wearing a shirt cuff. The plastic in the new model has become more glossy, which gives the device a premium look, but makes it more vulnerable to micro scratches.
Display comparison: AMOLED vs AMOLED
Both devices feature AMOLED-type matrices, which provide deep black and high contrast. However, the Mi Band 6 offers a much larger diagonal - 1.56 inches versus 0.95 inches from its predecessor. Resolution has also increased from 120×240 pixels to 152×486 pixels, making fonts clearer and images more detailed.
The brightness of the screen in the new model is higher, which allows you to comfortably read information even in direct sunlight. In the Mi Band 4 in the sun, you sometimes had to close the text with your palm to make out the readings. In addition, the sixth version introduced an automatic brightness control feature, which was lacking in the fourth.
- 📏 Screen area: Increased by 50% compared to the previous generation.
- 🛡️ Protection: Mi Band 6 uses glass 2.5D scratch-resistant oleophobic coating.
- 🎨 Dials: New model supports more complex and animated dials thanks to screen power.
An important aspect is the presence of Always-On Display in the Mi Band 6. This feature allows you to see the time and date without lifting your wrist. In the Mi Band 4, the screen is completely extinguished to save energy, and it requires a characteristic brush movement to view the time. For many users, having AOD becomes a decisive factor in choosing.
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Using Always-On Display significantly reduces battery life. If you want maximum duration of operation without recharging, it is better to adjust the activation of the screen only by raising your hand.
Health Sensors and Measurement Accuracy
The most significant changes have been in the sensory base of the devices. The Mi Band 4 is equipped with an optical heart rate sensor PPG, which is good at measuring heart rate at rest, but with sudden changes in load or high-intensity training, it can be delayed or give out errors.
The Mi Band 6 has an updated 6-axis accelerometer and gyroscope, and an improved optical sensor algorithm, but the main innovation has been the introduction of the oxygen saturation sensor (SpO2), a critical feature, especially in the post-pandemic period, that allows you to track blood oxygenation levels 24/7 or on demand.
The new model’s pulse accuracy is also better, thanks to the tighter skin-locking sensors and improved algorithmic signal processing. GPS-To record the route of a jog or a bike walk, both trackers require a connection to a smartphone.
| Characteristics | Xiaomi Mi Band 4 | Xiaomi Mi Band 6 |
|---|---|---|
| Pulse sensor | PPG (2nd generation) | PPG (improved) |
| SpO2 measurement | No. | There is. |
| Sleep monitoring | Basic | Expanded (REM-phase) |
| Stress. | No. | There is. |
The Mi Band 6 software also includes stress monitoring and more detailed sleep phase analysis, including the use of a new system of sleep. REM-The fourth version is able to distinguish between deep and light sleep, which gives a less complete picture of the body's recovery during the night.
Sports regimes and training functionality
The number of supported sports modes in the Mi Band 6 has grown to 30, while in the Mi Band 4 there are only 6 basic.If previously the user had to choose between "Running", "Bicycle" and "Swimming", now available specialized modes for yoga, elliptical trainer, rowing, rope and even dancing.
The interface became more informative during training, and the big screen of the sixth model puts more real-time data on the current heart rate, pace, distance traveled and calories burned. In the Mi Band 4, information had to be swiped, which is uncomfortable to do on the run.
- 🏊 Waterproof: Both devices have a rating of 5 ATM, This allows you to swim in the pool at a depth of 50 meters.
- 🏃 Automatic Detection: Mi Band 6 better recognizes the beginning of activity, suggesting to start the tracker when walking fast.
- 📊 Analytics: The Mi Fitness app (formerly Zepp Life) has more graphs and metrics available for the new model.
For professional athletes, none of the models will be suitable due to the lack of built-in GPS and limited load metrics. However, for fitness enthusiasts and supporters of healthy lifestyles, the Mi Band 6 is more than enough. The fourth version will be suitable for those who are exclusively engaged in running or walking and do not need specific modes.
Hidden sporting functions
Autonomy and charging process
The increase in screen size and the emergence of new sensors naturally affected the battery capacity, but not proportionally. The Mi Band 4 has a 135 mAh battery, while the Mi Band 6 has 125 mAh. It would seem that the new model should live less, but the optimization of the processor and screen allowed to maintain decent performance.
Under standard use (notifications, periodic pulse measurements, wrist lifting), the Mi Band 4 can live up to 20 days. the Mi Band 6 can run for about 14 days in similar conditions. If you include continuous heart rate monitoring, SpO2 and Always-On Display, the running time will be reduced to 5-7 days for both models, but for the sixth version it will be a more intense scenario.
The charging process has remained unchanged: the capsule must be removed from the strap and installed in a special charging dock, which is not the most convenient solution compared to the magnetic contacts on the rear panel, which appear in more expensive models of other brands.
⚠️ Warning: When you install the capsule in the charger, make sure the contacts fit tightly. In the Mi Band 6, because of the glossy surface, the capsule can slide, which will cause charging interruptions.
☑️ Check before buying a used tracker
Software and ecosystem
Both trackers work in conjunction with the Zepp Life app (formerly Mi Fit), although the Mi Band 6 is also fully compatible with the new Mi Fitness app. The fourth version of the app’s interface looks outdated, with fewer widgets and less flexible settings.
Compatibility with operating systems is wide: Android 5.0+ and iOS 10.0+ are supported. However, iPhone owners may face limitations: the inability to respond to messages (only view) and the lack of some widgets. On Android, the functionality is disclosed as fully as possible, including the ability to install custom dials through third-party applications.
The Mi Band 6 has more than 30 interface languages, including full-fledged Cyrillic without squares in some system messages, which was sometimes found in early firmware of the fourth model, and improved Bluetooth connectivity stability, and communication breaks became less common.
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Mi Band 6 offers a more modern software platform with support for new applications and widgets, which extends the relevance of the device in the market.