How do you format an unreadable SD card on Android?

Quick Answers

There are a few quick solutions you can try to format an unreadable SD card on Android:

  • Use your phone’s built-in SD card formatter – Go to Settings > Storage > Format SD card
  • Try a third party SD card formatter app like SD Card Formatter
  • Connect your phone to a computer and format the SD card using Windows Disk Management or Disk Utility on Mac
  • As a last resort, you may need to replace the SD card if it is corrupt or damaged

Formatting the SD card will erase all data, so be sure to backup anything important first. If formatting does not work, the SD card itself may be faulty and need replacing.

What Causes an SD Card to Become Unreadable?

There are several potential causes for an SD card becoming unreadable or unmounted on an Android device:

  • File system errors – The file system on the SD card may have become corrupted.
  • Improper ejection – Removing the SD card without properly unmounting it can cause issues.
  • Physical damage – Dropping or bending the SD card can damage it and make it unreadable.
  • Moisture damage – Exposure to liquids can short circuit and damage SD cards.
  • Outdated file system – Older SD cards may have FAT32 instead of the more modern exFAT.
  • Fake or low quality card – Counterfeit and cheap SD cards are more prone to failure.

If you are seeing errors like “SD card blank or has unsupported file system” or the SD card is detected but unable to be accessed, one of these factors is likely the cause.

How to Format an Unreadable SD Card Using Android Settings

The easiest way to format an unreadable or unmounted SD card is by using your Android device’s built-in SD card formatter:

  1. Go to the Settings app and select “Storage”.
  2. Select your SD card from the list.
  3. Tap “Format” or “Format as internal” if you want to set it as expanded internal storage.
  4. Confirm that you want to format when prompted.

This will wipe and reformat the SD card to fix any file system errors and make it usable again.

Some things to note with this method:

  • Move any data you want to keep off the SD card first.
  • You may need to try unmounting and remounting the SD card before formatting if it is not detected.
  • Not all Android devices have an integrated SD card formatting function.

If you do not see the option to format SD card in your device’s Settings, you will need to use a third party app or format it on a computer instead.

Using Third Party SD Card Formatter Apps

If your Android device does not give you the ability to format the SD card, your next option is to use a dedicated SD card formatter app. Here are some good options:

SD Card Formatter

SD Card Formatter by Elm Chan is a popular and widely used SD card formatter app on Android.

  • Simple interface with just a format button.
  • Works for SD, SDHC, and SDXC cards.
  • Ability to do a full format to overwrite all data.
  • Both FAT32 and exFAT file system options.

This app has been around for a long time and works well for reliably formatting SD cards that may be unreadable or unmounted.

SD Card Formatter for Android

This aptly named app provides another excellent option specifically tailored for Android users.

  • Format SD cards that are not detected or readable.
  • Quick and full format options.
  • Fixes unmounting issues.
  • Recover storage capacity from cards with bad sectors.

It is easy to use with a straightforward interface. An ad-supported free version is available.

Other Options

There are numerous other SD card formatter apps on the Google Play Store. Some other top options include:

  • MiniTool Mobile Recovery
  • Card Formatter
  • SD Card Formatter Pro
  • SdFix Card Formatter

Look for apps that specifically mention they support SD card formatting and repairing. Read reviews to confirm they work properly before downloading.

Formatting an SD Card Using a Computer

If you are unable to get your Android device to detect or reformat the SD card, a computer can provide a solution. Here is how to format an unreadable SD card using a Windows PC or Mac:

On Windows

  1. Connect the SD card to your computer using a card reader or adapter.
  2. Open File Explorer then right click on the SD drive and select “Format…”.
  3. Choose FAT32 or exFAT file system.
  4. Check the Quick Format box and click Start.

This will completely reformat the entire SD card and overwrite data making it usable again.

On Mac

  1. Connect the SD card to your Mac.
  2. Open Disk Utility.
  3. Select your SD card drive on the left sidebar.
  4. Click Erase at the top.
  5. Choose a name, file format (MS-DOS FAT is FAT32, exFAT).
  6. Click Erase.

Following these steps will format and repartition the SD card through your Mac.

Using Windows Disk Management

The Windows Disk Management utility provides more advanced options for managing connected storage drives. Here is how to use it to format an SD card:

  1. Go to Control Panel > Administrative Tools > Computer Management.
  2. Select Disk Management on the left sidebar.
  3. Right click your SD card drive and choose Format.
  4. Adjust settings like file system and allocate unit size.
  5. Click OK.

This gives you some more control over how the card is formatted versus the basic Windows format dialog.

When to Replace an Unreadable SD Card

If you’ve tried the Android settings, third party apps, and computer methods to format your unreadable SD card and nothing works, it likely means the card itself is faulty and needs to be replaced.

Signs that indicate it’s time to replace your SD card:

  • Multiple reformatting attempts fail.
  • SD card is detected but data is inaccessible.
  • Obvious physical damage like bends or scratches.
  • Errors referencing bad sectors or blocks.
  • Card reader detects issues or reports RAW format.
  • Card previously got wet or was in extreme heat.

While SD cards can last for years, they do eventually wear out or get damaged. Replacing an older, unreliable card with a new one can get your Android storage back up and running again.

When buying an SD card replacement, look for trusted brands like SanDisk, Samsung, or Kingston. Compare read/write speeds and capacity. An application class rating of A1 or A2 ensures good Android performance.

Tips to Avoid Unreadable SD Card Errors

To help prevent your SD card from becoming corrupted or unreadable again in the future, keep these tips in mind:

  • Safely eject the card before removing it from your device.
  • Be gentle and avoid dropping or bending the card.
  • Keep the contacts clean and clear of debris.
  • Store and use the SD card in normal ambient temperatures.
  • Upgrade older SD cards to newer versions for better performance.
  • Back up your SD card data regularly as a precaution.

Following best practices for using and caring for your SD card will help extend its usable lifespan. But cards do inevitably fail over time, so saving copies of your important data is always a good idea.


When an SD card becomes corrupted, undetected, or unreadable on Android there are still ways you can attempt to fix it. Using the built-in formatter in your device’s settings is the easiest option. Third party formatting apps provide alternatives when that doesn’t work. As a last resort, you can reformat on a Windows PC or Mac.

If no formatting method succeeds, however, the SD card is likely faulty and due for replacement. Buying a modern, high-quality card and using it properly will help prevent formatting issues going forward. But SD cards are inexpensive enough that replacing them when problems occur is straightforward. With a new SD card installed, you can continue expanding your Android’s storage capacity.