How to know exactly how old Xiaomi phone is: from serial number to hidden menus

Have you bought Xiaomi from your hands or found an old device in your desk drawer but don’t know when it was released? The age of a smartphone affects its performance, update support and market value. For example, models older than 4 years often lose official firmware, and the battery loses up to 30% of capacity. In this article, 7 working ways to determine the date of production of a Xiaomi phone, including analyzing the serial number, checking through IMEI and hidden engineering menus.

We will not only look at standard methods (through settings and boxes), but also little-known tricks, such as how to calculate the week of release by S/N or check the activation history through your Mi Account. Particular attention will be paid to the risks of buying fakes - some Chinese clones imitate Xiaomi serial numbers, and we will show you how to recognize them.

1. Serial number check (S/N) — most accurate

The serial number (S/N) is a unique device identifier that encodes the date of production. Xiaomi has a number format that depends on the year of release:

• 📅 2015–2018 years: format XXXXXXXXX (9 where the first number is 4 Numbers: year and week, for example, 7035 = 2017 year, 35-I'm a week).
• 📅 2019–2023 years: format XXXXX-XX-XXXXXX, second-group (2 numbers - year of issue (e.g, -21- = 2021 year).
• 📅 2026–...: New alphanumeric code format, where date is encrypted in the first 6 characters.

Where to find S/N:

• 📱 In settings: Settings → The phone. → General information → Serial number.
• 📦 On the box: under the barcode or on the sticker with IMEI.
• 🔋 Under the battery (for models with a removable lid, for example, Redmi) 4A).

💡

If the serial number starts with the letters MZ or LZ, it could be a fake. Xiaomi's original numbers contain only numbers (for older models) or a combination of numbers and letters in a strict format.

An example of decryption:

Serial number: 9A18D00523


9A18 → 2019, 18th week (April 2019)




- D00523 → factory code

⚠️ Note: On some models (e.g, POCO F1) The serial number in the settings may differ from the number on the box. This is not always a sign of a fake - check both options through the official Mi Verify service.

2. Determination of the IMEI release date

IMEI (International Mobile Equipment Identity) is another unique identifier that can be used to verify the age of a phone. Unlike the serial number, the IMEI does not contain a direct release date, but allows you to know the month and year of activation through carrier databases or services like IMEI.info.

How to check:

1. Find IMEI in Settings → About Phone → General information → IMEI or dial *#06#.
2. Go to IMEI.info and enter the number.
3. In the results, find the Date of First Activation field.

Note: the activation date may differ from the production date by 1-6 months (logistics and storage time). For example, if the phone was activated in March 2020, it was released no later than December 2019.

3. Check through hidden engineering menu (for advanced)

Xiaomi phones have a hidden EngineerMode menu where you can find the production date data, which works on most Qualcomm-based models (e.g. Redmi Note 8 Pro, Mi 9).

Instructions:

1. Open the Phone app and dial ##4636##.
2. Select Phone Information.
3. Scroll down to the Hardware Information block.
4. Find the Manufacture Date or Build Time string (YYYY-MM-DD format).

Enable Developer Mode (click 7 times on the MIUI version in the settings)

Charge your phone at least 50% (some menus are locked when charged low)

Write down all dates you find, which may be different from the serial number.

Do not change the settings in the engineering menu without knowing the consequences.-->

If the menu does not open, try the alternative codes:

• #284## - Equipment test (for some POCO models)
• #225### - Calendar information (works on Redmi 6/7)

⚠️ Note: On phones with Mediatek processors (e.g. Redmi) 9C) The engineering menu may contain false date information.

4.Analysing the box and stickers - what to look for

Xiaomi’s original packaging contains several production date markers:

• 📦 Barcode on a box: the first 4 digits after the letter prefix (e.g. 2001 in 69415672200123) may indicate a year and a week.
• 🏭 Sticker with IMEI: Under the barcode, the date is often printed in format YY/MM/DD (for example, 21/05/15 = 15 may 2021).
• 📝 Serial number on the box: must match the number in the phone settings (see section 1).

Examples of date stickers:

Please note the country of production (indicated on the box):

• 🇨🇳 Made in China – Most models until 2022.
• 🇮🇳 Made in India - Redmi and POCO for the Indian market (since 2019).
• 🇮🇩 Made in Indonesia: Redmi 9 and Redmi 10.

Always checking.

Check if the model is older than 2 years

I don't check, I trust the seller.

I don't know how to do that.-->

Verification through Mi Account (official method)

If the phone was linked to a Mi Account, you can find out the date of first activation through the web version of the service, which works even if the phone is reset to factory settings.

Instructions:

1. Go to account.xiaomi.com and log in.
2. Select the Devices tab.
3. Find your phone in the list and click on it.
4. In the Device Information section, the activation date field will be provided.

Limitations of the method:

• ❌ It doesn’t work if the phone isn’t tied to your account.
• ❌ The activation date may be later than the production date (see table in section 2).
• ❌ Some regional accounts (e.g. Indian accounts) may not display the date.

💡

If the Mi Account device list shows a model that doesn’t match your phone (like the Mi 9 instead of the Redmi Note 8), it’s a sign of motherboard swapping or a fake.

6. age assessment according to MIUI and support for updates

The MIUI firmware version indirectly indicates the age of the phone. Xiaomi releases updates for models no older than 3-4 years (excluding flagships). For example, if the phone is running a MIUI 12, it is released no later than 2021.

Table of conformity of MIUI versions and years of release:

How to check the MIUI version:

1. Open the Settings. → The phone.
2. Find the line MIUI version.
3. Compare it to the table above.

If your phone hasn’t received an update for more than 2 years, it’s over 4-5 years old – a critical threshold for battery replacement and motherboard status checks.

7. Visual signs of aging - when there is no access to data

If you can’t use digital methods (for example, the phone doesn’t turn on), assess its age by external signs:

• 🔋 Battery: bloating, rapid charge drop (less than 4 hours of operation) - a sign of age 3+ years.
• 📱 Body: rubbing on plastic, faded buttons - typical for models over 2 years old.
• 🔌 Charging port: backlash of connector USB-C Micro-USB – a signal for long-term use.
• 📸 Camera: scratches on the glass of the lens – more common on phones 2018-2019 (before the appearance of sapphire coating).

Example: Redmi Note 5 (2018) after 4 years of operation:

⚠️ Warning: Some signs (such as a bloated battery) may appear on new phones when charging incorrectly.Always combine visual verification with digital methods.

FAQ: Frequent questions about the age of Xiaomi phones