How to format a disk?

Formatting a disk is the process of preparing a disk for initial use by writing a file system onto it. This allows the operating system to organize files and folders logically on the disk. Formatting is typically done on new hard drives, USB flash drives, SD cards, and other storage media before they can be used to store files.

Formatting erases all existing data on the disk and allows you to choose a file system like NTFS or FAT32. Different file systems have advantages and disadvantages in terms of supported file size, maximum volume size, and compatibility across operating systems. Choosing the right file system depends on how you intend to use the disk.

Formatting is necessary to set up the logical structure on a disk before it can be used. It erases old data and allows the operating system to optimize the storage space for saving new files and folders. Formatting should always be done on new disks or when switching a disk between different operating systems.

When to Format a Disk

There are several common situations when you may need to format a disk:

  • When setting up a new disk – Formatting is necessary to prepare a brand new disk for use before you can save files on it. Formatting lays down the file system structure.
  • To thoroughly erase data on an old disk – Formatting completely erases all existing data on a used disk. It wipes the disk clean for reuse.
  • To resolve disk errors or problems – If a disk is experiencing corruption or errors, formatting can essentially reset it and resolve the issues.
  • To change the file system – You may want to reformat a disk to change it from one file system like FAT32 to another like NTFS. This allows it to be compatible with different operating systems.
  • When switching operating systems – Moving from Windows to Mac for example requires reformatting the boot drive to use a Mac compatible file system.

In general, formatting fully erases a disk and prepares it for reuse with a new blank slate. It’s necessary when configuring disks from scratch as well as when repurposing used disks.

Back Up Important Data First

Before formatting any drive, it is absolutely critical to back up your important files and data first. As the reformatting process will erase everything on the drive, you risk permanently losing photos, documents, music, or other irreplaceable data if you don’t properly back it up ahead of time.

There are several options for backing up your data before a format:

  • Copy files to an external hard drive or USB flash drive [1]
  • Back up to cloud storage services like Google Drive, Dropbox, or OneDrive
  • Burn files to CDs or DVDs

If you fail to back up your data and proceed with formatting the drive, the consequences can be severe. You may lose years worth of photos, videos, documents, music, and other personal or work files. Recovering lost files after a format is difficult, expensive, and not guaranteed.

To prevent data loss disasters, it’s wise to maintain regular backups even when you’re not planning to format a drive. Back up to an external location on a routine basis so you always have a recent copy of your files. Keep external drives in a safe place in case your computer is damaged, stolen, or crashes unexpectedly.

Backing up your irreplaceable data is a small price to pay for the peace of mind of knowing your files are safe before wiping a drive clean.

Formatting Options and File Systems

The three main file systems to choose from when formatting a drive are NTFS, FAT32, and exFAT. Each has advantages and disadvantages:

NTFS (New Technology File System) was introduced by Microsoft in 1993 for use with Windows NT. It is the preferred file system for internal hard drives in Windows 10/8/7. NTFS supports very large partition sizes (up to 256 TB) and large file sizes (up to 16 TB). It also provides good security with file/folder permissions and encryption capabilities. However, NTFS is proprietary to Windows and is read-only on Mac by default (Source).

FAT32 (File Allocation Table) originated in 1977 and was used in early versions of Windows and DOS. It is compatible with all major operating systems including Windows, Mac, and Linux. FAT32 works best with smaller partition sizes (up to 32 GB) and smaller files (up to 4 GB file sizes). It is simple and efficient, but lacks security features like permissions and encryption (Source).

exFAT (Extended File Allocation Table) was introduced in 2006 for use in flash memory cards and external drives. It supports very large partition and file sizes, even bigger than NTFS. exFAT is compatible with Windows and Mac without additional software. However, it lacks security features and is not ideal for systems files or boot partitions (Source).

For internal hard drives, NTFS is recommended for Windows and HFS+ for Macs. For external removable media, FAT32 is good for cross-compatibility while exFAT is ideal if you need very large file/partition support.

Another consideration is the partitioning scheme. MBR (Master Boot Record) is limited to 2TB partitions while GPT (GUID Partition Table) supports huge partitions over 2TB. GPT also allows unlimited partitions. For most home users, MBR is sufficient but GPT must be used for very large drives.

Allocation unit size also impacts performance and efficiency. Smaller units decrease wasted space while larger ones improve performance with large files. The default settings are usually optimal for each file system.

Finally, quick vs full formatting comes down to whether you want to fully erase all data or do a faster format. Quick formatting simply clears the file table while full formatting overwrites all data for security.

Using Disk Management Utility

The Disk Management utility in Windows allows you to easily format and partition hard drives. To access Disk Management:

1. Open the Start menu and search for “Create and format hard disk partitions.” Click on the result to open the Disk Management utility.

2. You can also open the Control Panel, go to System and Security > Administrative Tools, and launch Disk Management from there.

In the Disk Management window, you will see a list of all connected disk drives and their partitions. To format a drive:

1. Right-click on the drive you want to format and select “Format…”

2. Choose the file system – NTFS is recommended for Windows. Select the allocation unit size.

3. Check the “Perform a quick format” box to format faster. Click “OK.”

4. The format will now run and reformat the drive. Once completed, you can right-click and select “Change drive letter and paths” to assign a drive letter if needed.

Disk Management also allows you to easily partition drives to have multiple volumes on a single disk. This allows you to efficiently organize and separate data.

Using Command Prompt

The command prompt contains several formatting utilities that allow you to format disks quickly from the command line. The main tools are the format command and the diskpart utility.

The format command can be used to perform a quick format on a drive. To use it, open the command prompt and type “format X:” where X is the letter of the drive to format. This will perform a basic format on the drive (Source 1).

The diskpart utility provides more advanced formatting options. To use it, open the command prompt and type “diskpart”. This will open the diskpart prompt. From here, you can list disks with “list disk”, select a disk with “select disk X” where X is the disk number, and then use the “clean” command to format the drive (Source 2).

Diskpart also allows you to set additional format options like file system type and cluster size. You can also fully automate diskpart formatting in batch files for repeatable deployments.

Overall, the command prompt tools provide formatting options not available in graphical utilities like setting specific cluster sizes or automation via batch scripts. They allow quick and flexible formatting without a GUI.

Using Third-Party Tools

Third-party disk formatting tools provide more features and flexibility compared to the built-in Windows options. Popular free tools include:

The key benefits of third-party tools are the ability to customize options like file system type, cluster size, partition layouts, SSD optimization, and secure data wiping. They also allow formatting of external drives. The steps to format a drive using AOMEI Partition Assistant would be:

  1. Download and install the software.
  2. Run AOMEI Partition Assistant and select the target drive.
  3. Click “Format” and choose options like file system, cluster size, label name.
  4. Click “OK” to begin formatting the drive.

Overall, advanced third-party formatting utilities like AOMEI Partition Assistant provide the most options and controls for properly formatting hard drives.

On Macs

Macs use several different formatting options for disks and external drives. The most common Mac filesystems are Mac OS Extended and APFS. Mac OS Extended is optimized for Macs while APFS is a more modern filesystem optimized for solid state drives.

The easiest way to format a disk on Mac is using the built-in Disk Utility app. Disk Utility allows you to erase and reformat any connected drive. To reformat a drive, connect it to your Mac, launch Disk Utility, select the drive, click “Erase”, choose your desired format (e.g. Mac OS Extended), name the drive, and click Erase.

You can also format disks using the command line with the diskutil tool. For example, to format a drive named “MyDrive” as APFS, use:

diskutil eraseDisk APFS MyDrive disk2

If you want to use an external drive on both Mac and Windows, it’s best to format it as exFAT. This will allow full read/write access on both operating systems. To format as exFAT on Mac, choose exFAT in Disk Utility or use diskutil and specify “exFAT” as the format type.

On Linux

On Linux, there are several tools that can be used for formatting disks, including gparted, fdisk, and mkfs commands. To get started, you’ll first want to create partitions on the disk using either gparted or fdisk ( Gparted provides a graphical interface, while fdisk is used through the command line.

Once partitions are set up, you can use the mkfs (make filesystem) command to specify the file system type. Some common Linux file systems include ext4, XFS, Btrfs and JFS. Ext4 is compatible across Linux distributions and older versions of Windows, while XFS offers high performance for large files. Btrfs provides advanced features like snapshots and data integrity checks (

Here is an example mkfs command to format a partition as ext4:

sudo mkfs -t ext4 /dev/sdb1

You can also automate disk formatting in Linux using shell scripts. This allows you to reuse the commands instead of typing them each time. The script can partition, create file systems, mount disks, and more.


Here are some common issues and solutions for troubleshooting disk formatting:

If your drive is not showing up in File Explorer or Disk Management, try these steps:

  • Check physical connections and cables
  • Try connecting to another USB port
  • Restart your computer
  • Update disk drivers
  • Use diskpart to clean and create new partition

If the format fails or takes a very long time, it could indicate bad sectors or physical damage. You can try:

  • Scanning for and repairing errors with CHKDSK
  • Low-level formatting with diskpart
  • Trying a different file system like FAT32 instead of NTFS

If you get errors about bad sectors, the drive may be failing. Reformatting usually will not fix this. You’ll need to backup data and replace the faulty drive.

You cannot reformat the active system partition or boot drives through File Explorer. Use the command line or recovery media instead.

If disk utilities become non-responsive during formatting, allow extra time to complete or reboot and try again. Failing drives can cause freezes.