How to accurately determine the date of production of the Xiaomi phone: all the ways from the serial number to hidden menus

Buying a Xiaomi smartphone in the secondary market is always fraught with risks: the seller can hide the real age of the device by masking it as “near-new”. The date of production directly affects the residual battery life, the relevance of the hardware platform and even the cost of the gadget. For example, the Redmi Note 10 Pro, released in 2021, by 2026, can lose up to 30% of the battery capacity – which is critical for daily use.

In this article, we will analyze all the official and hidden methods of how to find out the date of production of the Xiaomi phone - from decrypting the serial number to analyzing the factory tags under the battery. You will learn to distinguish fake data from real data (for example, some sellers replace the information in the settings through the engineering menu), and also understand which Xiaomi models encode the date in the data. IMEI, Instructions are valid for all lines: Redmi, POCO, Mi and Black Shark.

1. Method: Decoding of the serial number (S/N)

The serial number (S/N) is a unique device identifier that contains encrypted information about the date of production.

• 📅 Do 2018 year-end: 4-and 5-And the symbols are the week, 6-y - year (e.g., year, 7A9 = 9-I'm a week. 2017 year-end).
• 📅 2018–2020 years: 4-y symbol - year (letter: 8=2018, 9=2019, 0=2020), 5–6-y-week.
• 📅 Since 2021: the format has changed – the date is encrypted in 3-6 characters by algorithm YYWW (year + week-long).

Where to find the serial number:

1. In phone settings: Settings → About phone → General information → Serial number.
2. On the device box (barcode sticker).
3. Under the battery (for models with a removable lid, for example, Redmi 4A).

Important: Some POCO models (e.g., POCO X3 NFC) use an alternative format where the date is encrypted in the last 4 characters. If your serial number is not decryptable, move on to the next one.

Method: IMEI verification

IMEI (International Mobile Equipment Identity) is another unique identifier that sometimes contains production date data, but Xiaomi doesn't use it for all models.

1. Find out your phone's IMEI: Dial *#06#, and a window with a 15-digit code will appear. Look at the sticker under the battery or on the box.
2. Decode. 7–8-Symbols (for some models): 🔢 19 = 2019 year, 20 = 2020 year, 21 = 2021 year. 🔢 The following: 2 Numbers - week (for example, 2035 = 35-I'm a week. 2020 year-end).

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If the IMEI starts with 86, it's a Chinese version of the phone (for example, for the Mi China market), such devices may have firmware restrictions for global regions.

⚠️ Note: since 2022, Xiaomi has stopped encrypting the date IMEI for most models (except for some flagships of the Mi 12 series). IMEI Does not contain any specific year numbers, use other methods.

3. Method: factory sticker under the battery

The most reliable method is to inspect the factory sticker, which is located under the battery (for models with a removable back cover) or under the protective film on the case (for monolithic devices), which indicates the exact month and year of production in MM/YYYYY or YYYY-MM-DDD format.

How to access:

• 🔧 For Redmi. 5A/4X/3S: Put the lid on with a plastic card (start with the corners!).
• 🔧 For POCO X3 NFC: unscrew 2 screws at the connector USB-C and gently lift the lid.
• 🔧 For monolithic models (Mi 11, Redmi Note 11): the sticker can be under the speaker's protective mesh or under the tray SIM-map.

Yes, always |Only if I buy with my hands |No, I didn't think |I don't know how to do it-->

⚠️ Note: if the sticker is damaged or missing, it is a sign of unofficial repair or forgery. IMEI.

Check the serial number in the settings|Compare. IMEI boxed|Use the app. CPU-Z iron-test|Ask the seller for a check or a guarantee card-->

Method 4: Engineering menu and service codes

Xiaomi’s hidden menus contain technical information, including the date of production, but access to them requires caution – wrong actions can lead to failures.

Instructions:

1. Open the Phone app and type in: ##4636##Select Phone Information →Scroll to Hardware info block.
2. For models on Qualcomm (e.g. Redmi Note 10), type: ##225### In the Calibration section, find the MFG Date string.
3. For MediaTek (POCO M3, Redmi 9A): ##36446337## Go to Hardware Testing → Version.

Example of output: MFG Date: 2021-07-15 (July 15, 2021).If no date is available, the menu does not support this feature.

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The engineering menu may vary depending on the version of MIUI. If the code doesn't work, upgrade the firmware to the latest stable version.

Method: Applications for diagnostics

If manual methods don't work, use third-party utilities that analyze hardware data and often pull the production date out of system logs.

Top.-3 apps:

• 📱 CPU-Z: dervice → Manufacturing Date (works on 80% of models).
• 📱 AIDA64: partition → Production Date (requires root for full access).
• 📱 Mi Check (official): scanning QR-code from the box and shows the release date.

⚠️ Note: Some apps (such as Phone) INFO) They can show the date of the first activation, not the date of production!

Method: Checking by batch number (Batch Number)

The batch number is the internal code that Xiaomi assigns to each batch of devices, and can be found on the box or in documents. Format: XMXXXXXXXXXXX, where:

• 🔢 First-time 2 post-signature XM — year, 21 = 2021).
• 🔢 The next 2-3 characters are a week or a month.

Example: XM210812345 → August 2021 (year 21, 08) This method works for models released after 2019.

Where to find Batch Number:

• On the box sticker next to the barcode.
• In the warranty card (if you bought in the official store).
• In settings: Settings → About Phone → MIUI → Additional (not for all models).

Frequent Mistakes and How to Avoid Them

Many users encounter inaccurate data when checking the production date. Consider the typical pitfalls:

1. Fake stickers: Fraudsters can replace the factory sticker under the battery, always check it against the serial number in the settings.
2. Serial number errors: Some Xiaomi models (e.g. Redmi K40) have a floating S/N format – the date can be encrypted in non-standard characters.
3. IMEI mismatch: If the IMEIs on the box and on the phone are different, it is a sign of a re-energized or restored device.

How to minimize the risks:

• 🔍 Check the date at least. 2–3 methods (e.g, S/N + sticker + engineering menu).
• 🔍 Use the official Mi Verify service to authenticate your identity IMEI.
• 🔍 If you buy from hand, ask the seller to take a photo of the stickers under the battery before the meeting.

FAQ: Answers to Frequent Questions