How the fitness bracelet Xiaomi Mi Band 4 counts calories: analysis of algorithms and practical nuances

The Xiaomi Mi Band 4 fitness bracelet has become one of the most popular activity tracking gadgets thanks to its combination of affordable price and wide functionality. One of the key features of the device is counting burned calories, a parameter that excites both beginners and experienced athletes. But how does the bracelet calculate energy costs, how accurate and can it be trusted? In this article, we will examine in detail the Mi Band 4 algorithms, the influence of external factors on accuracy and how to improve measurement results.

Many users experience discrepancies between the bracelet readings and other devices (such as smartphones or professional pulse gauges). To understand why this happens, you need to delve into the technical aspects, from the types of sensors used to the mathematical formulas embedded in the firmware, we will also analyze how individual characteristics of the body (age, weight, gender) affect the final numbers and what to do if the bracelet clearly “lies”.

What sensors are responsible for counting calories in Mi Band 4

The Xiaomi Mi Band 4 is based on a set of three main sensors, the data of which are used to calculate energy consumption:

• 🔴 Optical heart rate sensor (PPG) — It measures the pulse through the skin of the wrist by analyzing changes in blood flow. Heart rate (HR) is a key parameter for most calorie formulas.
• 🏃 accelerometer 3D — It detects acceleration and movement of the hand in three planes (X, Y, Z). Allows you to determine the type of activity (walking, running, sleeping) and its intensity.
• 🌡️ Skin temperature sensor – indirectly involved in algorithm adjustments, especially in determining sleep and stress phases.

It's important to understand that the Mi Band 4 doesn't measure calories directly, but instead it collects raw data from sensors and then applies complex mathematical models to them, like an accelerometer that records the number of steps and the amplitude of movements. PPG-This data is combined with the user’s personal parameters (weight, height, age) embedded in the Mi Fit app and passed through algorithms developed by Xiaomi.

One of the most well-known algorithms used in fitness trackers is the formula. MET (Metabolic Equivalent of Task: It assigns each activity an energy input (e.g., walking 3.5). MET, run - 7 MET), And then it multiplies it by the user's weight and the activity time, but the Mi Band 4 uses its own modification of this formula, which takes into account the pulsemeter data for a more accurate adjustment.

Calorie Calorie Calculus Algorithms: From Steps to Complex Formulas

The calorie counting process in Mi Band 4 can be divided into three stages:

1. Data collection: sensors record pulse, movement, activity/rest time.
2. Activity classification: algorithms determine what the user is doing (walking, running, sleeping, etc.).
3. Calculation of energy consumption: formulas are used taking into account individual parameters.

For walking and running, the bracelet uses a simplified model:

Calories = (number of steps × step length) × activity coefficient × user weight

Where Step length is calculated automatically based on growth (default: growth in cm) × 0.413 for men and × The activity coefficient depends on the pace: for example, when walking at 5 km/h, it is equal to ~3.5 and running 10 km/h — ~8.

For other activities (bicycle, swimming, exercise) the bracelet uses fixed MET-The odds that you can find in the documentation of Xiaomi:

The Mi Band 4 doesn’t automatically recognize all activities — for example, cycling or swimming needs to be manually run through the bracelet menu or the Mi Fit app. If you forgot to do that, the bracelet will count your bike ride as “active walking,” which will lead to low calorie counts.

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To make the bracelet count calories more accurately during exercise, always choose the appropriate mode manually, for example, use the "Running" mode for running, rather than relying on automatic determination.

Why the bracelet is lying: 5 key reasons

Even with the right settings, the Mi Band 4 can show inflated or understated data.

• 📏 Mi Fit: If you have the wrong weight, height or age on your Mi Fit profile, the algorithms will use the wrong ratios, for example, if you are underweight, the bracelet will show fewer calories than you actually burned.
• 💓 Problems with pulse measurement: PPG-The sensor is sensitive to bracelet density, sweating, tattoos, or dark skin, and if the pulse is not correctly recorded, calorie counting will also be inaccurate.
• 🚶 Automatic activity detection: The bracelet may mistook a trip in transport for walking or miss short but intense loads (for example, climbing stairs).
• 🔋 Outdated firmware: newer versions of the software, Xiaomi improves algorithms, for example, after upgrading to firmware 1.0.9.54, the accuracy of walking steps increased by a factor of two. ~15%.
• 🌡️ External conditions: at low temperatures, sensors may work less stable, and at high humidity (for example, in a sauna), the bracelet can count sweating for activity.

According to independent tests (for example, from the channel Techmoan), the error of Mi Band 4 in calorie counting is 15-30% compared to professional devices like Polar. H10 Or Garmin Forerunner, and for walking and running, the accuracy is higher. ~10-15 percent, and for strength training or swimming, lower (up to 40 percent%).

⚠️ Warning: If the bracelet shows abnormally high calorie expenditure (e.g., 1,000)+ Calories per hour of walking, check the density of the strap. Too tight or weak fastening distorts the data. PPG-sensor, which leads to errors in calculations.

How to improve calorie counting accuracy: step-by-step instructions

To minimize errors, follow these guidelines:

Update the bracelet firmware to the latest version|Make sure that your Mi Fit profile shows your current weight, height and age|Wear the bracelet 2-3 cm above the wrist bone (not on the wrist itself)|Enable the option “Improving sleep tracking” in Mi Fit settings»|Start your training regimes manually for non-standard activities-->

Additionally, you can calibrate the bracelet to your parameters:

1. Walk 100 steps while holding a smartphone with the step counter turned on (for example, through Google Fit).
2. Compare the phone and Mi Band 4. If the difference is greater than 10%, adjust the step length in the Mi Fit settings:
3. Go to Profile. → Settings for Mi Band → Step length and enter the value calculated by the formula: New step length = (Real distance / Number of steps by Mi Band) × 100

For the pulsemeter, the correct position of the bracelet is critical:

• 🩹 The strap should sit tightly, but not squeeze your hand (you can stick your finger between the skin and the bracelet).
• 🖐️ The optimal position is on the back of the forearm, not on the wrist, especially when training.
• 🚿 Avoid wearing the bracelet while showering or swimming – water may distort the signal PPG-sensor.

Comparison with other devices: who is more accurate?

To assess the real accuracy of the Mi Band 4, compare it with other popular fitness trackers according to tests from Wareable and the other popular fitness trackers. DC Rainmaker:

As you can see from the table, the Mi Band 4 is exactly ahead of many budget devices, but the main advantage of the bracelet is the price / function ratio. For amateur training, its errors are not critical, but professional athletes are better to consider devices with chest sensors (for example, Polar). H10).

Interestingly, the Mi Band 4 test scored better on running than on strength training, because Xiaomi’s algorithms are optimized for cyclic loads (walking, running, cycling), where it’s easier to analyze rhythmic movements, and for the gym, it’s better to use specialized apps like Strong or Hevy that synchronize with the bracelet.

⚠️ Note: If you use Mi Band 4 to track your sleep, note that the bracelet overstates calories during sleep. REM-REM sleep phases by 20 to 30 percent, which is associated with an increase in heart rate, which algorithms interpret as physical activity.

Mi Band 4 Calorie Counting Myths: Dispelling Misconceptions

There are many myths surrounding fitness trackers, and we'll look at the most common ones in the Mi Band 4:

• 🔋 «The more you sync the bracelet to your smartphone, the more accurate the data is, "" wrong. Synchronization only transfers data to the app, but it doesn't affect the measurements themselves.
• ⚡ «If the bracelet is dead, the calorie data per day is lost" — not exactly. Mi Band 4 stores data for the last 7 days in its memory.
• 💪 «The bracelet counts muscle mass in calorie counting. "" No. Algorithms only work on weight, height, age and gender. People with high muscle percentages (like bodybuilders) will understate energy expenditure.
• 🍽️ «Mi Band 4 can count calories from food, no. The bracelet only counts calories, not calories. It requires specialized applications like MyFitnessPal).

Another common misconception is that the wristband gets used to the user and becomes more accurate over time. In fact, the Mi Band 4 does not use machine learning: its algorithms are static and do not adapt to individual features, but regular firmware updates can improve accuracy due to improvements from Xiaomi.

Some users believe that if the bracelet shows a high resting heart rate, it is "broken."

• Stress or lack of sleep (heart rate really increases).
• Consuming caffeine or energy drinks.
• Incorrect positioning of the bracelet (for example, too high on the forearm).

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The Mi Band 4 is not a medical device, but is an evaluation and cannot be used to diagnose disease or accurately monitor diet.

Alternative ways to track calories: when bracelets aren't enough

If you want a higher accuracy than the Mi Band 4 can provide, consider the following options:

• 🩺 Breast pulsemeters (for example, Polar) H10 Wahoo Tickr – The accuracy of heart rate measurement ±1 beats/min, which gives a calorie error of no more than 5%, and can be synced with the Mi Band 4 via Mi Fit or third-party apps.
• 📱 LiDAR smartphones (like iPhone 12 Pro and later) – some apps (like Strava) use a laser scanner to more accurately track movements.
• 💻 Smart scales with body composition analysis (for example, Xiaomi Mi Body Composition Scale 2) – help to adjust calorie expenditure data based on muscle mass and hydration level.
• 📊 Professional trackers (such as Garmin Fenix 7 or Suunto 9) – use multi-channel sensors and adaptive algorithms, but cost 5-10 times more than the Mi Band 4.

For maximum accuracy, you can combine several devices.

1. Use Mi Band 4 to track your steps and sleep.
2. Connect the chest pulse meter for training.
3. Enter the nutrition data in MyFitnessPal and sync it with Mi Fit.

If you have a budget, you can upgrade your Mi Band 4 firmware and keep track of your profile, and after upgrading to 1.0.9.54, your calorie counting accuracy improved 12 to 18 percent by optimizing your activity recognition algorithms, according to Xiaomi.

FAQ: Frequent questions about calorie counting in the Mi Band 4