How the pedometer works in the fitness bracelet Xiaomi Mi Band 4: technologies, errors and secrets of accuracy

Why does the Mi Band 4 pedometer show different numbers?

Have you ever compared the pedometer data on the Xiaomi Mi Band 4 to other devices or applications and noticed discrepancies? Maybe the bracelet overstates the number of steps when you're driving in a vehicle, or vice versa, it "loses" some activity while walking. These errors are not accidental: they depend on the principles of the built-in sensors, the algorithms for processing data and even on how you wear the bracelet.

In this article, we'll go into detail about how the Mi Band 4 pedometer captures movement, what technology is responsible for it, and why it can be different from reality, how it distinguishes walking from driving, why it sometimes resets steps, and what to do to make the data as accurate as possible, and compare the accuracy of the Mi Band 4 with other popular fitness trackers.

If you want to not just trust the numbers on the screen, but understand where they come from, this guide is for you, and let's start with the most important thing, the bracelet stuffing, which is responsible for counting the steps.

What sensors are responsible for counting the steps in the Mi Band 4?

The pedometer is based on a triaxial accelerometer, a microchip that detects the bracelet’s acceleration in three planes: X (left-right), Y (back-to-back) and Z (up-down), and the Mi Band 4 uses an accelerometer model ADI ADXL362 from Analog Devices, which consumes minimal energy, but is able to capture even minor hand movements.

Aside from the accelerometer, the bracelet has a gyroscope, but it is used mainly to detect gestures (like raising your hand to see the time) rather than counting steps. However, gyro data can indirectly influence the algorithms for filtering false positives, such as when you wave your hand but don’t walk.

Here's how it works in practice:

• 📊 The accelerometer records the rhythmic vibrations of the hand with frequency ~1-2 Hz (typical step frequency when walking).
• 🔄 The processing algorithm analyzes the amplitude and frequency of these fluctuations, sifting out random movements.
• 🧠 Microcontroller (Dialog chip) DA14680) Converts raw data to steps using pre-loaded motion profiles.

Interestingly, the Mi Band 4 doesn't use GPS to count steps -- this module is missing from the bracelet -- instead, it relies solely on motion sensor data, which explains some of the errors, for example, if you're walking at a straight line, the algorithm can add extra steps because it doesn't see the trajectory change.

Data processing algorithms: how the bracelet distinguishes walking from random movements

The raw data from the accelerometer is just a set of numbers showing acceleration at different points in time, and to convert it into meaningful activity metrics, the Mi Band 4 uses several layers of algorithms:

1. Noise filtering: The device ignores high-frequency vibrations (e.g. hand tremors when writing) and movements with atypical amplitude (e.g. sudden swings).
2. The algorithm looks for the repetitive cycles of movement that characterize the step: first, the hand moves forward, then backward, with peak acceleration in the middle.
3. Adaptive calibration: The bracelet learns to match the user's walking style: if you often walk with a bag in one hand, it will adjust the sensitivity over time.
4. Contextual analysis: Additional factors are taken into account: time of day (at night, steps are considered stricter), heart rate (if your heart rate is elevated, you are more likely to actually move).

One of the key features of the Mi Band 4 is that it dynamically changes the sensitivity threshold, for example, if you sit for a long time and then stand up abruptly, the first few steps may not count, the algorithm will perceive them as random movement, and vice versa: if you walk exactly 10 minutes, the bracelet will "understand" that this is a purposeful activity, and will record the steps more accurately.

But there is a downside to this approach: the bracelet can mistakenly count steps when driving on rough roads or when working with a vibrating tool (such as a drill), which is because the accelerometer detects vibrations similar to the rhythm of walking.

Pedometer accuracy: comparison with other fitness trackers

Independent tests show that the Xiaomi Mi Band 4 has an average step error of ±5-10% for normal walking, compared to the Apple Watch Series 5, which is about ±3-7%, while budget models without a brand can reach ±20%.

The Mi Band 4’s main advantage is its price-to-function ratio, which is inferior to the flagship smartwatch in exactness, but for most users, the 5-10% difference is not critical, and the margin of error can be reduced by following a few simple rules.

⚠️ Note: If you wear a bracelet on a non-dominant hand (for example, on the right hand, if you are left-handed), the accuracy of step counting may fall on the head. 10-15%. This is because the movements of the leading hand are more rhythmic and predictable for algorithms.

How to increase the accuracy of the pedometer: 7 practical tips

Mi Band 4 is not perfect, and you can improve its accuracy by following these guidelines:

It's especially important to set up a profile in the Mi Fit app correctly, for example, if you put an incorrect growth, the algorithm will not correctly calculate the length of the step, which will lead to an overstatement or an understatement of the distance, to update the data:

1. Open the Mi Fit app.
2. Go to Profile → Device Settings → Personal Information.
3. Indicate current height, weight and date of birth.
4. Save the changes and wait for the synchronization with the bracelet.

Another useful life hack: if you're a sportsman (running, cycling, swimming), use special training regimes in the bracelet, in which case the step-counting algorithms adapt to a particular activity, for example, when choosing a "bicycle" mode, the bracelet will ignore the rhythmic hand movements that it could count for steps.

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If you notice that the bracelet is constantly overstating steps, try turning off the auto-activity function in the Mi Fit settings. This will reduce the number of false positives, but will require manual training.

Common Pedometer Mistakes and How to Avoid Them

Even with the right setup, the Mi Band 4 can be wrong. Here are the most common problems and solutions:

• 🚗 The reason is that the vibrations of the steering wheel are like the movements of the hand when walking. Solution: remove the bracelet or switch it to flight mode during the trip.
• 🛏️ The reason for this is that if you turn or tremble (for example, from the cold), the accelerometer may work. Solution: activate the "Do Not Disturb" mode for the night.
• 🏃 The reason is that when you run fast, the algorithm can lose some of the steps. Solution: Use the Running mode on the bracelet to calculate more accurately.
• 💻 Steps count when you're working on a computer, and the reason is that you're moving your mouse or typing on your keyboard creates vibrations, so you can either hold the bracelet tighter or you can take it off while you're working.

One of the most insidious mistakes is to reset your data after you update your firmware. If you update your bracelet through Mi Fit, make sure that:

1. The battery level is not lower than 50%.
2. The bracelet is located next to the smartphone (distance is not more than 1 meter).
3. You do not interrupt the update process (this may result in the loss of all data for the last month).

⚠️ Note: If after updating the firmware pedometer began to work incorrectly (for example, shows 2 times more steps), reset the bracelet settings to the factory. → Additionally. → Reset.

Technical Limitations: Why a Pedometer Will Never Be Perfect

Despite the tricks of Xiaomi’s engineers, the physical limitations of the accelerometers make it impossible to count 100% of the steps accurately.

• 📏 Individual stride length: The bracelet uses averages (e.g, 0.7 m for men and 0.6 m for women), but the actual length of the step may vary by 10-20%.
• 🔋 Energy saving: To extend battery life, Mi Band 4 reduces the frequency of sensors to 10-20 Hz (for comparison: professional trackers use it) 50-100 Hz).
• 🧭 Absence GPS. Without location data, the bracelet cannot adjust the steps based on distance traveled (for example, if you walk in a circle).
• 🤖 Simplified algorithms: Budget devices don’t use neural networks to analyze movements, like Apple’s flagship models or Garmin’s.

Fun fact: if you walk on an escalator, the Mi Band 4 will count it as activity, when you don't actually make an effort. More expensive trackers (like the Garmin Vivosmart 4) can tell passive from active motion by analyzing heart rate and acceleration.

For most users, however, the Mi Band 4 is accurate enough — especially if you use it not for professional training, but to motivate movement — to understand the limitations of the device and not expect lab accuracy.

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The Mi Band 4 is optimized for everyday use, not professional sports, and has a margin of error of ±10% offset by low price, long operating time and convenience.

FAQ: answers to frequent questions about the Mi Band 4 pedometer