How do I fix a window that is unable to format?

Quick Overview

There are a few potential reasons why you may be experiencing issues with formatting a window on your computer, such as an error message stating “Windows was unable to complete the format” or similar. Some common causes include corrupted system files, bad sectors on the hard drive, issues with disk partitioning, or incompatible hardware/drivers. Fortunately, there are steps you can take to troubleshoot and resolve this problem.

First, try running the CHKDSK utility to scan for and repair disk errors. You can also check the hard drive for bad sectors using a tool like SeaTools. If that doesn’t fix it, create a bootable disk or USB drive and try formatting from the Windows recovery environment. Make sure your hard drive is using the GPT partition style if you’re on a UEFI system. Updating drivers, doing a clean reinstall of Windows, or replacing faulty hardware may be necessary if those other steps don’t work.

What Does “Windows Unable to Format” Error Mean?

The “Windows was unable to complete the format” error occurs when the Windows operating system cannot successfully format a drive or volume. Formatting prepares a storage device like a hard disk drive or USB flash drive by writing a file system to it and creating the necessary file tables and structures.

Some common scenarios where you may encounter this error include:

– Attempting to format an internal or external hard drive and receiving this error.

– Trying to reformat a partition or volume on a disk and getting this message.

– Installing Windows on a new hard drive, reaching the formatting step, and being unable to complete it.

– Using the SUBST command to mount a partition as a folder and getting a “unable to format” error.

The main causes stem from disk corruption, bad sectors, or incompatible hardware/firmware. The format process is unable to fully write the required data and file structures to the disk due to these physical defects or incompatibilities. That results in the vague but ominous “unable to complete the format” message.

Common Causes for a Windows Format Failure

There are a number of potential reasons why the formatting process may fail and generate this error:

Corrupted system files – System file corruption can prevent the proper execution of formatting tools like the Windows Format utility. Running SFC /scannow can check for and restore damaged files.

Bad sectors – If areas of the hard disk contain bad sectors, they cannot be written to properly during formatting. Hard drive utilities can locate and quarantine bad sectors.

Partition issues – Problems with the disk’s partition table or type (MBR vs GPT) may cause format failures. Deleting and recreating partitions can rectify these issues.

Incompatible hardware – Issues with disk controllers, drives, connectors, or drivers can lead to format failures. Check hardware compatibility lists and update drivers.

Insufficient permissions – Admin-level permissions are required to format drives in Windows. Logging in as an admin rather than standard user may resolve this.

Malware infection – Viruses and other malware sometimes target critical system files or partitions necessary for successful formatting. Antivirus scans can uncover and remove infections if present.

How to Fix “Windows was Unable to Complete the Format”

If you encounter the “Windows was unable to complete the format” error when trying to format a volume or partition, there are a number of troubleshooting steps you can take to fix the problem:


CHKDSK analyzes the file system integrity of your drive and attempts to repair any logical file system errors or bad sectors. To run it:

– Open the Command Prompt as administrator
– Type “chkdsk X: /f” (substitute X for the letter of your drive)
– Allow CHKDSK to complete which could take a while if errors are found
– Retry formatting the drive after it finishes

2. Check for bad sectors with SeaTools

SeaTools is a free hard disk diagnostic program from Seagate that can check for bad sectors.

– Download and install SeaTools for Windows
– Run the Short Drive Self Test on your target drive
– If bad sectors are detected, use SeaTools’ Repair function or back up data and reformat

3. Format using diskpart

The DISKPART command line utility has enhanced formatting capabilities that may succeed where Windows’ GUI format failed:

– Open the Command Prompt as administrator
– Type “diskpart” to launch utility
– Type “list disk” and identify your target drive’s disk number
– Select this disk via “select disk X” (X=disk number)
– Use “clean” command to wipe and reformat entire disk

4. Boot from Windows recovery media

You may be able to format the drive using the Windows recovery environment:

– Insert your Windows recovery disk or USB and change BIOS boot order to boot from media
– Boot into recovery options
– Select Troubleshoot > Advanced options > Command Prompt
– Use diskpart at command prompt to clean or format disk

5. Change partition scheme to GPT

For UEFI systems, changing partition scheme to GPT may allow format on newer drives:

– Use diskpart’s “clean” command to delete existing partitions
– Create new primary partition and format as NTFS
– Convert disk to GPT via “convert gpt” command
– Retry formatting original partition

6. Update drivers

Outdated disk controller or SATA drivers can disrupt formatting actions. Update drivers from manufacturer website or Device Manager.

7. Low-level format

Low-level formatting fully resets drive by overwriting data platters and may resolve issues not fixed by standard quick format.

8. Clean reinstall Windows

If drive issues still persist, cleanly reinstalling Windows on the computer may allow proper reformatting and use of the drive.

How to Avoid “Windows Unable to Format” Error

While disk errors and hardware faults typically cause format failures, there are preventative measures you can take to avoid these issues:

– Regularly run error-checking scans using CHKDSK to find and repair logical file system problems

– Install the manufacturer’s hard drive tools like SeaTools to periodically check disk health

– Make sure your computer meets Windows’ system requirements for partitioning and formatting features

– Keep your hard disk drivers, firmware, and storage controllers up-to-date

– Don’t interrupt formatting process or force power off during drive reformats

– Use a UPS to prevent unexpected power interruptions during critical drive operations

– Back up your files and data regularly in case you need to low-level format and wipe your drive

– Consider switching to solid state drives which have no bad sectors compared to mechanical drives

– When partitioning, align partitions properly and leave at least 16MB of unallocated space for alignment

– Use Windows’ Optimize Drives utility to defragment HDDs prior to any major partitioning or formatting

Following best practices for drive maintenance, hardware selection, and Windows installation can help avoid or minimize instances where disk errors block the formatting process entirely.

When to Reformat vs Repair a Hard Drive

When faced with hard drive errors or format failures, should you reformat and wipe the drive or try repairing it instead? Here are some guidelines:

Try repairs first – Things like CHKDSK and SeaTools are less destructive than reformatting. Run them to fix logical errors.

Reformat if bad sectors found – If utility scans find actual bad sectors, formatting is required since physical defects can’t be repaired.

Format for clean OS install – When reinstalling an operating system, formatting removes old OS files for a fresh start.

Format to change file systems – To change the file system from FAT32 to NTFS for instance, the drive must be reformatted.

Repair if issues intermittent – If problems happen infrequently, repairs may be sufficient vs wiping drive and restoring backups.

Reformat if drive acting very erratic – Strange behavior like very slow transfers or high bad sector counts warrant reformatting.

Repair important personal files drive – Try repairs first on drives containing irreplaceable data or files vs immediately reformatting.

Reformat if repairs fail repeatedly – At some point after multiple failed repairs, it becomes necessary to reformat and start over.

In general, attempt repairs first as they are non-destructive. But if problems persist or worsen, a complete reformat and repartitioning of the drive may be required to fix underlying disk defects.

Formatting from BIOS vs Windows Recovery vs Install Media

When experiencing formatting issues in Windows, there are a few different environments you can boot into to attempt formatting the drive again:


– Accessible on any PC by starting computer and entering BIOS setup
– Typically allows low-level format of internal hard drives
– Useful for removing master boot record viruses

Windows Recovery Environment

– Boots limited Windows environment off recovery partition
– Has utilities like System Restore and Startup Repair
– Can access Command Prompt to format drives with diskpart

Windows Install Media

– Boots from USB or DVD with full Windows setup files
– Access recovery tools and Command Prompt like RE
– Can fully reinstall Windows on a formatted drive

The Windows recovery options are the least disruptive, followed by physical media, then BIOS low-level formatting as most destructive. Try recovery first, then media for clean installs, then low-level format in BIOS as last resort if hardware issues are suspected.

Tips for Avoiding Formatting Errors

Follow these tips to help avoid formatting failures when installing Windows, partitioning drives, or performing drive maintenance:

– Update BIOS, chipset, and storage drivers to latest available versions
– Disable antivirus scans during formatting to prevent access conflicts

– Connect drive to different SATA port or USB port if possible

– Use recommended file systems for your partition’s usage – NTFS for Windows system and data partitions above 32GB

– Delete existing partitions before creating new ones if reformatting existing drive

– Verify sufficient power supply for high capacity drives – may need supplemental power cables

– Don’t interrupt or abruptly shut down during formats – wait for processes to complete

– If an external USB drive, check enclosure wiring/connections and try different cables

– Back up data and be prepared to low-level format and zero-fill drive if necessary

– In diskpart, use ‘clean’ instead of ‘format’ command to fully reset drive if partition errors

– Boot from Windows installer media to format disks during OS clean installs

By following best practices and troubleshooting guidelines, most issues that lead to Windows being unable to format a drive can be resolved, allowing you to recover the use of your storage device.

Recovering Data after Reformatting Drives

If you reformatted a disk without properly backing up files first, there are recovery options:

Restore from backup – Retrieve files from any backups created earlier (best option).

Use data recovery software – Utilities like Recuva can restore deleted files after quick reformat.

Send to data recovery service – They attempt to recover data after reformatting using specialized tools.

Restore previous version – If File History was enabled, you may restore older copies of files.

Recover data on reformatted partition – Provided the partition size hasn’t changed, some data may be retrievable.

Restore system image backup – If a full system image was created earlier, all files can be restored.

Check Recycle Bin – Files deleted during reformat may still be in the Recycle Bin temporarily.

The odds of recovering data decrease after a full reformat, but backups provide the greatest chance. Going forward, be diligent about regularly backing up drives to avoid permanent data loss when reformatting.

Frequently Asked Questions

Why does Windows give a vague “unable to format” error?

Windows is designed to hide low-level disk errors from users for simplicity. The operating system detects the format did not complete successfully but doesn’t pinpoint the exact reason. More advanced disk utilities can provide specific details on format failures.

Can I format a drive to FAT32 in Windows 10?

Yes, the FAT32 file system is still available as a formatting option in Windows 10. Open the format dialog box, select FAT32, and check the box to perform a quick format. However, NTFS is recommended over FAT32 for Windows system partitions.

Should I use a quick or full format on an external hard drive?

For most external drives used for backup or basic storage, a quick format is sufficient. Full formats scan the entire drive for bad sectors, which is useful for system hard drives but not necessary for external backup devices.

Why does my formatted drive show less space than advertised?

A portion of a drive’s total capacity is reserved for internal use by the file system and disk alignment. Formatting may appear to “take” space but is actually just allocating overhead space required for the formatted partitions.

Can chkdsk fix bad sectors?

Chkdsk can fix logical file system errors but cannot physically repair bad sectors on a hard disk. Bad sectors require a format to quarantine. SeaTools and other diagnostics tools can check for true physical bad sectors.


The “Windows was unable to complete the format” error generally appears when an issue prevents a drive or partition from being formatted properly. Causes range from corrupted files to bad sectors to hardware incompatibilities. Fixes like chkdsk scans, driver and firmware updates, switching partition style from MBR to GPT, and reformatting via diskpart or bootable media can often resolve these difficult errors. But in severe cases of disk defects, replacing faulty hardware may ultimately be needed. By understanding what causes formatting failures and how to troubleshoot them, you can recover use of your drive and recover valuable data otherwise at risk of permanent loss.