Does reformatting an external hard drive erase it?

Quick Answer

Reformatting an external hard drive does effectively erase all the data stored on it. The reformatting process overwrites the existing file system and partition table with a new blank file system, rendering the previous data inaccessible. However, the data is not completely erased from the drive and can still be recovered using data recovery software.

What Happens When You Reformat a Hard Drive?

Reformatting a hard drive involves restructuring the file system and partition table to create a fresh blank slate. Here is what happens in more detail when reformatting a drive:

  • The existing file system structure containing all your files and folders is overwritten with a new blank file system, deleting all the data that was stored.
  • The partition table that defines the partitions on the drive is rewritten, erasing all previous partitions.
  • A new blank file system is created, which appears empty when you open the drive.
  • The reformatting process does not actually erase the raw data stored on the drive platters. The data remains physically intact until overwritten by new data.

So essentially, reformatting renders the data inaccessible by deleting the file system that organizes the data and allows the operating system to access it. But the underlying data remains recoverable until the reformatting process overwrites it with new data written onto the drive.

Does Reformatting Actually Erase Data Permanently?

No, reformatting does not permanently erase or wipe a hard drive. Although the process makes the data inaccessible to the operating system, the raw data remains intact on the drive platters until it gets overwritten by new data.

Here are some key points on how reformatting affects data erasure:

  • The reformatting process only overwrites the file system metadata, not the actual user data.
  • All the sectors containing user data remain untouched and recoverable.
  • It may take weeks or months before all reusable sectors are overwritten by new data.
  • Reformatting resets the logical mapping but does not touch the physical data.
  • With the right forensic data recovery tools, the formatted data can be recovered.
  • Simply reformatting does not securely erase data from a hard drive.

In summary, the reformatting process cannot be relied upon to completely wipe a hard drive. Sensitive confidential data remains recoverable even after reformatting the drive.

Can Reformatted Hard Drive Data Be Recovered?

Yes, data on a reformatted hard drive can still be successfully recovered using the right data recovery tools. Here are some key ways to recover data from a reformatted drive:

  • Use data recovery software that can scan the drive and reconstruct the previous file system.
  • Look for data signatures of different file types to recover deleted data.
  • Access the raw sector data directly and extract recoverable user files.
  • Employ forensic methods to restore partition tables and file system structures.
  • Repair the reformatted file system back to its previous usable state if possible.
  • Perform a deep sector-by-sector scan to recover formatted data.

Many data recovery apps use a combination of these techniques to maximize the chance of recovering data after reformatting a hard drive. The effectiveness depends on the reformatting method used, how much new data was written, and the software algorithm.

But in most cases, a large percentage of formatted data can be recovered as long as the drive remains physically functional.

Examples of Recovered Reformatted Hard Drive Data

Here are some real-world examples of data successfully recovered from reformatted hard drives:

  • Photos and documents: A drive reformatted from NTFS to FAT32 was recovered, retaining family photos, Word docs, and PDF statements.
  • Email archives: An Exchange server drive accidentally reinitialized was recovered, restoring 10GB of previously deleted emails.
  • Database files: A reformatted MySQL database server drive had critical database tables containing customer data recovered.
  • Outlook PST files: A reformatted hard drive had Outlook PST files recovered, bringing back archived emails and calendar items.
  • Design files: A studio artist had Adobe Photoshop PSD files successfully recovered after mistakenly reformatting an external design portfolio drive.

These examples demonstrate that properly implemented data recovery methods can often salvage a significant amount of data from reformatted hard drives across various file formats and use cases.

Factors Affecting Reformatted Drive Data Recovery

The chances and extent of recovering data from a reformatted hard drive depend on several key factors:

  • Time elapsed – The longer since reformatting occurred, the higher the chance of data overwrite.
  • Capacity used – A fuller drive has less empty space for data overwrites.
  • Data fragmentation – More fragmentation makes recovery trickier.
  • File system – Complex file systems like NTFS have lower recovery success.
  • Reformatting method – Full vs quick reformatting impacts recovery levels.
  • Write activity – More writes of new data reduces recoverability.
  • Physical state – Damaged drives have lower recovery odds.

Understanding these factors allows proper assessment of the feasibility and complexity of recovering reformatted drive data in different situations.

Can You Recover Data After Reformatting Several Times?

Reformatting a hard drive multiple times makes data recovery more difficult but not always impossible. With each reformatting pass:

  • There is increased risk of data overwrite as more sectors get reallocated.
  • Fragmentation is reduced, consolidating residual data to contiguous areas.
  • File system structures get more complex with traces of previous formats.
  • Recovery software faces additional challenges to rebuild file systems.

However, data recovery can still be successful after multiple reformats if:

  • Sufficient unused space remains protecting data from overwrites.
  • Drive platters retain magnetic data traces from previous writes.
  • Recovery tools can interpret complex multi-layered file system remnants.
  • Enough identifying file patterns exist to reconstruct file contents.

In summary, while the difficulty increases, recovering data still remains possible even after reformatting a drive multiple times, especially if it involves just quick reformats. The recovery feasibility ultimately depends on the drive capacity and usage levels.

Can Reformatting Be Used to Wipe a Hard Drive?

Reformatting a hard drive is generally not an effective method for permanently erasing data and wiping a drive. This is because reformatting only removes the file system structure – the underlying data still remains recoverable.

To reliably wipe a hard drive:

  • Use drive eraser tools that overwrite all drive sectors multiple times.
  • Utilize built-in ATA Secure Erase commands to reset drive to factory state.
  • Degauss the drive magnetically to disrupt magnetic data patterns.
  • Physically destroy drive platters to prevent any chance of data recovery.

Simply reformatting the drive once is not sufficient to prevent highly skilled recovery of deleted data. Multi-pass data overwriting or physical destruction of the drive media is required for reliable and permanent data wiping.

Can You Recover Data from a Reformatted External Hard Drive?

Yes, the data recovery principles discussed so far apply equally to external hard drives that have been reformatted. When an external USB or eSATA hard drive is reformatted, the data remains intact on the drive platters and can be recovered by:

  • Removing the drive from its external enclosure and connecting it directly like an internal drive.
  • Booting into a recovery operating system or recovery tools external environment.
  • Imaging the external drive to another attached drive for analysis.
  • Scanning and extracting recoverable file data remnants.

As long as the external drive hardware remains undamaged, a significant amount of data can be recovered even after reformatting the external hard drive. Higher cost professional lab data recovery services also specialize in recovering reformatted external drives.

How Reformatting Differs from Deleting Files or Partitions

Reformatting a hard drive is different from simply deleting files or partitions:

  • Deleting files only removes file system references to the data, not the data itself.
  • Deleting partitions only removes the partition table information, not the contained data.
  • Reformatting destroys the entire file system structure and replaces it with a blank one.

So reformatting involves more structural changes to the drive formatting than standard file or partition deletion. However, at a data recovery level, reformatting a drive has a similar outcome – the data is no longer accessible but remains recoverable.

Software Tools to Recover Reformatted Hard Drive Data

Here are some software tools that can effectively recover data after reformatting a hard drive:

  • Ontrack EasyRecovery – Has advanced capabilities to rebuild reformatted partition structures and file systems.
  • Stellar Data Recovery – Great at raw file signature scanning to extract data from reformatted drives.
  • Disk Drill – Excellent lost partition recovery to restore partitions lost in reformat.
  • R-Studio – Uses powerful file carving algorithms to extract maximum data.
  • Photorec – Open source tool good for recovering image, video, and document files.

These DIY recovery tools can recover substantial amounts of reformatting data for a fraction of professional lab costs. Testing them on non-critical drives first is advisable before relying on them for critical reformat recovery.

Should You Reformat a Hard Drive to Wipe Data?

Reformatting a hard drive is generally not an effective method to securely wipe data. As explained earlier, data remains recoverable after reformatting.

Instead, use these methods to wipe a hard drive properly:

  • Use multi-pass data overwriting tools that meet security standards.
  • Utilize inbuilt ATA Secure Erase functions on modern drives.
  • Degauss drives magnetically using strong degaussing wands.
  • Physically destroy drives beyond any chance of data recovery.

Simply reformatting a drive once only deletes file system structures. Sensitive data remains recoverable even after reformatting a drive multiple times. Use drive wiping tools or physical destruction when your aim is permanent erasure.

Can You Recover Files After Reformatting to a Different File System?

Reformatting a hard drive from one file system to another, like FAT32 to NTFS or HFS+ to APFS, still keeps the underlying data recoverable.

When reformatting to a different file system:

  • The previous file system structure and contents are overwritten.
  • A new blank target file system is created on the drive.
  • All previous files become inaccessible via the new file system.
  • But the raw data still physically remains on the drive.

So the new file system is simply a logical structure change that makes the old data invisible. But data recovery tools can still scan drive sectors directly, bypassing the file system, to recover lost files.

The effectiveness may vary based on differences between the old and new file systems. For example, recovering lost HFS+ files after reformatting to APFS may pose more challenges than FAT32 to NTFS. But advanced recovery methods can still successfully recover a substantial amount of data in most cases.

Can a Quick Format Recover Data?

A quick format is faster but less secure than a full format when reformatting a drive. It simply erases the file system information without overwriting any user data areas.

The advantages of a quick format for data recovery are:

  • No risk of data getting overwritten during the reformatting process.
  • Greater likelihood of file system structures remaining partially intact.
  • Higher chances of recovering data via file system reconstruction.
  • Fast recovery process without needing deep data extraction methods.

Quick formats are preferable when intentionally trying to recover data from a drive reformat. However, for securely erasing data, quick formats are ineffective since user data remains easily recoverable.

Can Reformatting Damage a Hard Drive?

Reformatting a hard drive does not directly damage the physical drive hardware. It only affects logical structures on the drive. However, there are exceptional risks to watch out for when reformatting:

  • Sudden power loss during reformatting can corrupt drive structures.
  • Accidentally reformatting the wrong non-backup drive results in data loss.
  • Bugs in reformatting software utilities can potentially damage drives.
  • Excessively reformatting SSD drives wears down their write endurance.

So while reformatting aims to fix drive issues, in rare cases it can also lead to physical drive faults or exacerbate existing problems. Having a valid backup before reformatting is strongly advised.


Reformatting a hard drive effectively erases all accessible user data by overwriting the file system. However, the underlying raw data still remains intact and recoverable by data recovery software until replaced with new data. So reformatting does not reliably wipe a hard drive clean. Sensitive data remains recoverable even after multiple reformats unless the drive is completely overwritten or physically destroyed. While reformatting damages logical file system structures, the physical drive components remain unaffected if the process completes smoothly without errors or interruption. Having a complete data backup before reformatting is strongly recommended to avoid permanent data loss. With adequate recovery tools and expertise, recovering a substantial amount of erased data from a reformatted drive is typically possible if the drive hardware itself remains reusable.