Having issues formatting your SD card can be frustrating. There are a few common reasons why an SD card may not format properly and several steps you can take to try and resolve the problem. This article will provide an overview of the most likely causes and solutions to try when your SD card refuses to format.
Quick Overview of the Main Reasons an SD Card Won’t Format
There are a few main reasons why you may be unable to format your SD card:
- The SD card is corrupted – Issues like bad sectors can prevent formatting
- The SD card is write protected – The lock switch being enabled prevents formatting
- The SD card is unallocated – No partition is defined to format
- There are errors with the SD card reader/slot
- The SD card is fake or counterfeit
- The SD card is damaged – Physical damage can prevent proper formatting
We’ll now go into more details on each of these common issues and how to troubleshoot them.
Corrupted SD Card
One of the most common reasons an SD card cannot be formatted is because it has become corrupted. A corrupted SD card will often have bad sectors or other logical errors that prevent the full formatting process from completing successfully.
There are a few major causes of a corrupted SD card:
- Improperly ejecting the SD card from devices
- Power outages or device crashes while writing data
- Exceeding the maximum read/write cycles of the SD card
- Physical damage to the card
- Malware or viruses infecting the SD card
When corruption occurs, the operating system will be unable to properly read, write, or format the SD card fully. Some signs your card may be corrupted include:
- Errors or failure when trying to access files on the SD card
- Unreadable folders or file names
- Strange characters in folder/file names where there should be normal letters/numbers
- SD card seeming full despite no visible files taking up space
If you suspect your SD card is corrupted, there are a few steps to try and fix it:
- Use the CHKDSK utility on Windows to scan for and repair errors
- Reformat the SD card using the full format option (not quick format)
- Try formatting the SD card on a different device
- Use a third party utility like SD Card Formatter to fully format the card
In severe cases of corruption, an SD card may be unrecoverable and need to be replaced entirely if these steps do not resolve the issue.
SD Card is Write Protected
Another reason your SD card may refuse formatting is if the write protection is enabled. SD cards have a small switch on the side that can toggle write protection on and off.
If the lock switch is slid down to the locked position, it will prevent any writes to the SD card. Formatting requires writing to the card, so it will fail with a write protected card.
To resolve this, simply slide the lock switch back up to the unlocked position. The card should now allow formatting again. Just be aware that with write protection disabled, new data can now overwrite existing data.
Unallocated SD Card
In order for an SD card to be formatted, it must first have an allocated partition mapped out. This dedicates a specific region of storage to use as the filesystem.
If you insert an SD card that is completely unallocated (no partition defined), it will not allow formatting. The system has nowhere to write the filesystem information.
To fix this, you need to create a new partition layout:
- Open Disk Management on Windows or Disk Utility on Mac
- Find the SD card and create a new partition spanning 100% of the disk space
- Select a filesystem like FAT32 or exFAT
This will allocate the full capacity of the SD card to a usable partition. You can now reformat this partition from Windows Explorer or other utilities.
SD Card Reader/Slot Issues
Problems with the SD card reader or slot in your computer itself can also prevent properly formatting cards. The main issues that can arise with readers include:
- Corrosion or dust buildup on contacts
- Broken/bent pins inside card slot
- Card reader not securely connected to motherboard
- Outdated or corrupt drivers for the card reader
- Card reader hardware failure
If you are having issues formatting multiple SD cards in one device, the issue may lie with the reader hardware or drivers. Some steps to isolate and potentially fix include:
- Trying the same card in a different device
- Updating drivers for the card reader
- Inspecting pins in the card slot for any damage
- Using a different card reader via USB or other external options
If the SD card formats without issue on a different device, then the reader is likely the root cause.
Fake or Counterfeit SD Card
There are many counterfeit and fake capacity SD cards being sold. These cards often claim to be much higher capacity than they really are. When you try to format them to the full fake capacity, it will fail.
Signs of a fake SD card include:
- Stated capacity seems excessively large at a low price
- Unknown or non-brand name card
- No packaging or counterfeit/altered packaging
- Capacity changes as you format or write data
If you suspect your card is fake, use a program like H2testw to check the real capacity. This will write data to fill the card and determine its true size.
You may be able to format the card to its actual smaller capacity. But fake cards often have reliability issues and should be replaced entirely.
Physical Damage to the SD Card
Lastly, physical damage from drops, bends, water exposure, or other trauma can render an SD card unformattable. The most fragile components include:
- Gold contact pins – scratches or corrosion can interfere with connections
- Microchip – cracks or lifted pads can cause data errors
- Controller – damage can disable communication
Signs of physical damage making an SD card unformattable include:
- Visible cracks in the casing or chips
- Card not detected at all when inserted in devices
- Bent or uneven shape indicating internal component damage
- Burnt smell or scorch marks indicating shorts
In cases of physical damage, the SD card is typically irrecoverable. A new SD card will need to be purchased as a replacement.
Best Solutions When SD Card Won’t Format
If your SD card is refusing to format, we recommend following these general steps to resolve:
- Try formatting on a different device – This will tell you if the issue is localized to one PC/reader or the card itself
- Check for write protection lock on the SD card to make sure it is disabled
- Scan for errors and attempt data recovery if needed
- Reseat the card and check the pins/connectors are clean
- Use disk utilities like DiskPart and CHKDSK to fully clean and repair the card
- If the card appears physically damaged, try to exchange it if still under warranty
- As a last resort, replace the damaged SD card with a new one
Following this troubleshooting flowchart should help identify the cause and lead you to the proper solution for getting the card formatted properly again.
Conclusion
While a stubborn, unformattable SD card can be immensely frustrating, there are usually identifiable reasons why the format process fails. By methodically tracking down the issue, whether it stems from software corruption, physical damage, or something else, you can find the right fix and get back to actually using the storage space on the card.
We hope this overview gives you a great starting point to diagnose and resolve your SD card formatting problems. Just remain patient and keep an organized approach. With the right troubleshooting steps, your SD card should be back up and running in no time.