How to connect Xiaomi Body Composition Scale S400 Smartphone: Full Instruction 2026

Introduction: Why Smart Scales Are Needed and How They Work

Xiaomi Body Composition Scale S400 — It's not just a weight-measuring device, it's looking at 13 key parameters of the body, including fat percentage, muscle mass, water level, even bone density, but to access that data, you need to connect the scales properly to your smartphone through an official app.

Many users face problems at the interface stage: the device is not located, the data is not synchronized, or the application gives an error. In this article, we will discuss all the ways of connecting, including solving typical errors, the instructions are relevant for Android and iOS, and also take into account the features of the latest versions of the Mi Fit and Zepp Life applications (formerly Mi Health).

If you have just unpacked the scales or are trying to reconnect them after resetting – this guide will help you avoid common errors and set up the device the first time.

What is included in the kit and how to prepare the scales for connection

Before you start setting up, check the Xiaomi configuration S400. The box should be:

• 📦 The scales themselves with a protective film on the sensors
• 🔋 4 type batteries AAA (Sometimes in a package, sometimes purchased separately)
• 📄 Short instructions in several languages (including Russian)
• 🔑 The key to adjusting the legs (if any)

If you don’t have batteries, buy alkaline (not rechargeable!) with voltage. 1.5V. Cheap salt batteries may not provide stable operation of sensors.

Preparation of the scales for the first inclusion:

1. Remove the protective film from the metal contacts on the platform.
2. Install batteries, observing polarity (the diagram in the compartment indicates the location). + and −).
3. Place the scales on a flat, hard surface (not on the carpet!) The legs should touch the floor with all four points.
4. Press the scales with your foot – the display should appear 0.0 or --.--.

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If the display doesn't turn on, check the contacts of the batteries: sometimes they oxidize during storage. Wipe them with a wipe or an alcohol wipe.

Which app to use: Mi Fit or Zepp Life?

Since 2023, Xiaomi has been gradually replacing Mi Fit with Zepp Life, a new application with advanced analytics. S400. We'll figure out which one is better to choose:

We recommend Zepp Life for users who want detailed body composition analysis, and if you only need basic functions (weight, BMI), Mi Fit is enough.

Download the applications can be by reference:

• 📱 Mi Fit for Android
• 🍎 Mi Fit for iOS
• 📱 Zepp Life for Android
• 🍎 Zepp Life for iOS

Step-by-step: how to connect Xiaomi S400 phone-in

The pairing process takes no more than 5 minutes, if you follow the algorithm, we will analyze the connection through Zepp Life (for Mi Fit, the steps are similar, but with a different interface).

Step 1. Registration of an account

• 📱 Open Zepp Life and click Register.
• 📧 Enter email or phone number (registration by number is available for Russia).
• 🔐 Create a password (minimum 8 characters, with numbers and letters).
• ✉️ Confirm the mail or enter the code from SMS.

Step 2: Adding a device

1. On the main screen, click. + (device-mark).
2. Choose the category Smart scales.
3. Find the Xiaomi Body Composition Scale S400 (If not, choose the other scales).
4. Press Connect.

Step 3: Synchronize over Bluetooth

• 🔵 Turn on Bluetooth on your phone (unless it is automatically enabled).
• 👣 Stand on the scales with bare feet (sensors work through the skin!).
• 📱 Wait until the icon appears on the scale display. BT lettering CONN.
• 🔄 In the app, click Confirm Connection.

Install batteries.|Download Zepp Life/Mi Fit|Turn on Bluetooth|Standing on the scales with bare feet|Stay within radius. 1 yard-->

If the scales are not there, try:

• 🔄 Reboot Bluetooth on your phone (Settings) → Bluetooth → Off./On.).
• 🔋 Remove and insert batteries in the scales.
• 📱 Remove the app cache (phone settings) → Annexes → Zepp Life → Memory. → Clear the cache).

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Xiaomi Libra S400 Only Bluetooth 4.0 supports Bluetooth 4.0+. If your phone is older than 2015, check compatibility in the specs.

User Profile Setting: Why It Matters for Accuracy

Once connected, the scales will show not only weight, but also individual body composition metrics, and you need to fill out the profile correctly in the application, and errors in the data (such as incorrect height or age) will distort the results of the analysis of fat, muscle and water.

How to set up a profile:

1. Open Zepp Life and go to Profile (the human icon at the bottom of the screen).
2. Click Edit and fill out the fields: 📏 Growth (in cm, to within 1 cm). 🎂 Date of birth (age affects fat/muscle norms). ♂/♀ Gender (male/female – norms differ!). 🏃 Activity level (sedentary, moderate, active).

Save the changes.

Critical error: if you specify the sex of “male” instead of “female” (or vice versa), the scales will underestimate / overestimate the percentage of fat by 3-5%, this is due to the different distribution of subcutaneous fat in men and women.

Once you save your profile, stand on the scale again, and the data will be calculated based on your parameters, and the application will also suggest setting goals (for example, weight loss or muscle set) and track progress.

Common Mistakes and How to Fix Them

Even with the right connection, users are facing problems. TOP-5 errors and solutions:

1.The scales are not included or show Lo

Reason: batteries that are discharged or incorrectly installed.

• 🔋 Check the polarity of the batteries (plus to plus!).
• 🔄 Try batteries from another manufacturer (e.g. Duracell or Energizer).
• 🧹 Clean the contacts in the battery compartment with a cotton swab soaked in alcohol.

2.The app doesn't see the scales

Reasons: Bluetooth is disabled, scales are not in pairing mode, interference from other devices.

• 🔵 Make sure Bluetooth is on on the phone and the scales show CONN.
• 📱 Restart the Zepp app Life/Mi Fit.
• 🚫 Disable other Bluetooth devices (earphones, fitness bracelets).
• 🔄 Reboot the phone.

3. Data is not stored or synchronized with delay

Reasons: weak Bluetooth signal, old app cache, account problems.

• 📶 Bring the phone closer to the weights (maximum 1 meter).
• 🗑️ Clear the app cache (Settings) → Annexes → Zepp Life → Memory. → Clear the cache).
• 🔄 Log out of your account and log in again.
• 📲 Update the application to the latest version.

4.The scales show the wrong weight or body composition

Causes: improper profile, wet or dirty feet, uneven surface.

• 🧼 Wash your feet with a dry towel before weighing in.
• 📏 Check height and age in your profile.
• 🏠 Place the scales on a solid, flat surface (not on a carpet!).
• ⚖️ Weigh yourself at the same time (better on an empty stomach in the morning).

5. the application gives an error "Device not supported"

Reason: an outdated version of the application or firmware scales.

• 📲 Update Zepp. Life/Mi Fit in the App Store or Google Play.
• 🔄 Reconnect the scales (remove them from the list of devices and add again).
• 📧 Write in support of Xiaomi with the weight model and the version of the application.

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If the scales show weight but don't send it to the app, try weighing twice in a row. Sometimes the first measurement wakes up the Bluetooth module.

Compatibility with other devices and services

Xiaomi Body Composition Scale S400 You can integrate with other devices and platforms for integrated health monitoring:

1. synchronization with Google Fit and Apple Health

To automatically transfer data to standard health applications:

1. Open Zepp Life. → Profile → Settings → Data management.
2. Choose Google Fit or Apple Health.
3. Log in to your account and allow access.

Weight and other metrics will now be duplicated into standard apps, where they can be read by other fitness services (such as MyFitnessPal or Samsung Health).

2 Connect to the Mi Home Smart Home

Libra S400 They do not support direct integration with the Mi Home, but you can bypass this restriction:

• 🏠 Install Mi Home and log in to the same account as Zepp Life.
• 🔄 Weight data will be available in the Mi Home Health Profile (but without detailed body composition analysis).

3.Export data to Excel or Google Sheets

To analyze the dynamics, you can unload the history of measurements:

1. In Zepp Life, go to Weight. → History.
2. Click Data Export (cog or three dot icon).
3. Select the period (week/month/year) and format (CSV or Excel).
4. The file will be sent to email or saved in Downloads.

Tip: To visualize progress, import data into Google Sheets and build charts with the feature =SPARKLINE().

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Xiaomi Libra S400 They don't have their own memory, all the data is stored in the app. If you delete the account, the measurement history will be lost!

How to Lose Scales to Factory Settings

If the scales start to glittle (incorrect readings, constant connection errors) - reset will help.

Method 1: Software reset via application

1. Open Zepp Life. → pick out the scales S400.
2. Go to Device Settings → Disconnect the device.
3. Confirm removal.
4. Then add the scales again (as with the first connection).

Method 2: Hardware reset (if the scales do not answer)

If the scales are not connected to the phone:

1. Take the batteries out for 30 seconds.
2. Hold the button. SET (If you have one, or press the scales and hold for 10 seconds.
3. Put the batteries back in - the scales will be reset to the factory settings.

After resetting, all data from the scale memory will be deleted, but the history in the application will remain (if the account was not deleted).

FAQ: Answers to Frequent Questions