Format Hard Drive

If you’re installing a new hard drive, or you’re selling your computer, trying a new operating system, or setting up an external drive for backups, sometimes you need to completely erase and format a hard drive. Here are the basic steps involved.

Formatting will check the drive for errors, and prepare it for use. If a drive has data on it, formatting the drive will remove all of the pointers to your files. Formatting can take hours to complete, but it is a good option when you have a new or inherited drive that is not properly formatted, a drive overrun by malware or other software problems, or a drive in need of a fresh start before a Windows installation.

Formatting doesn’t securely erase the contents of a hard drive. With freely available and easy-to-use tools, anyone can successfully recover data from a formatted drive. Traditional, magnetic-platter hard drives as well as solid-state drives can be formatted. Before you begin, be sure to back up important files on the disk before you format.

File Systems Explained

When you first set up a hard drive for use with a computer, you have to format it using a file system. Different operating systems (like Windows, Mac OS X, and Linux) use different file systems to organize and store data, so you need to use the file system most applicable for your needs. Here are a few of the more popular file systems you’ll see:

  • NTFS: This is Windows’ default file system. Windows can read and write to NTFS-formatted drives. OS X and Linux can only read NTFS-formatted drives, but not write to them—unless you have a third-party driver like NTFS-3G installed.
  • FAT32: is an older file system. You can’t install newer versions of Windows on a FAT32 system, but it can be handy for external drives since it can be read and written to by Windows, OS X, and Linux. However, it has one major downside: You can only store files 4GB or smaller on a FAT32 drive, which means it isn’t ideal for large files like movies.
  • ExFAT: ExFAT is less commonly used, but is similar to FAT32 without the downsides. Both Windows and OS X can read and write ExFAT-formatted drives, and it can store files over 4GB. This makes it ideal for flash drives.
  • HFS Plus: Also known as Mac OS Extended, this is OS X’s default file system. OS X can read and write to it. If you’re running Windows on your Mac with Boot Camp, you can read HFS Plus drives, but not write to them. A third party tool like Paragon HFS+ will allow any Windows system to read and write to HFS Plus drives.

These are just a few examples of popular file systems, and the only ones you’ll really encounter as a Windows or Mac user. Which one you use depends on the drive and what you’re using it for. For example, if you have an external drive you only use with Windows computers, you’ll want to format it as NTFS. If you have a drive you’re using with Windows PCs and Macs, ExFAT is probably the best option.

Note that when you format a hard drive, it erases all the content on your drive, so make sure you choose the right file system before you copy your data. In some cases, it’s possible to convert your drive without losing files—like converting a hard drive from FAT32 to NTFS—but under most circumstances, the only way to change your file system is to erase the drive and format it from scratch.

How to Format an External Drive or Flash Drive

So you’ve just bought a new external drive or flash drive, and you need to start using it. Note that we recommend formatting every drive you buy, even if it works when you plug it in—many external and flash drives come with extra software that, in our opinion, isn’t very good, and formatting it removes that annoyance (not to mention gives you a bit of extra space on the drive).

In Windows

To format an external drive in Windows:

  1. Plug your drive into the computer and, if necessary, into a wall outlet.
  2. Open Windows Explorer, click the "Computer" section in the sidebar, and find your drive.
  3. Right-click on the drive and choose "Format".
  4. Under "File System," choose the file system you want to use. See the above section for more details on which one to pick.
  5. Give your drive a name under "Volume Label," and check the "Quick Format" box.
  6. Click "Start" to format the drive. You’ll get a notification when it’s done (it should only take a few seconds).

To partition and format internal drive, you can use Windows built-in tool called Disk Management. In Windows 10 and Windows 8, the Power User Menu gives you the quickest access to Disk Management. You can also open Disk Management from the Command Prompt in any version of Windows but opening it via Computer Management is probably easier unless you’re really quick with commands.

When you’re done, open up the drive in Windows Explorer and you can begin dragging files to it, or backing up your computer. Remember that when you format a drive, it won’t show the exact same amount of free space as it does on the box. This is because computers measure space differently than they are marketed, so you’ll never get that exact same number, at least on Windows.

Format a RAID drive

If you have two or more disks configured as a RAID, there are various ways to format these drives. Before you use any of them, make sure you back up any files you want to keep.

  1. Use a software utility which came with your RAID controller or motherboard.
  2. Go into the RAID controller’s BIOS (look for a message during PC boot up) and look for an option to format the drive(s) or reconfigure the RAID as individual disks (this will erase them all).
  3. Unplug the drive you want to format and connect it to a different SATA port on your motherboard which isn’t part of the RAID controller. Then, follow the Windows Disk Management method below since the disk won’t be visible in Windows Explorer.


To format an external drive on a Mac:

  1. Open Finder and go to /Applications/Utilities and double-click on Disk Utility.
  2. Select your drive in the left-hand sidebar and go to the Erase tab.
  3. Under the "Format" menu, choose the file system you want to use. See the above section for more details on which one to pick.
  4. Give your drive a name and click the Erase button. It should only take a few seconds to format your drive.

When you’re done, click on the drive in Finder. You can start dragging files to it, or set it up as a backup drive with Time Machine.

How to Format Main Hard Drive

If you are formatting your primary hard drive with the intention of reinstalling Windows or restoring your PC to its factory-fresh state, you’ll need the restore disc(s) that came with your computer. If your computer manufacturer did not include restore media or you’ve misplaced it, contact the manufacturer directly for a replacement. You obviously can’t erase the drive while you’re using it, so you’ll need to format from a bootable CD or USB drive. What tools you use depend on what you’re trying to do.

If you’re going to sell your computer or the hard drive, you’ll want to securely wipe it using these instructions beforehand. After you’ve done so, you can reinstall your operating system (if necessary) as described below.

If you just want to reinstall your operating system (or install a new one), the installer can do the formatting for you. Just insert your Windows, OS X, or Linux installation disc (or drive), boot from it, and enter the installation.

If you’re installing OS X or Linux, you usually just need to choose the option to install from scratch, which will erase your drive. In the Windows installer, wait until you get to the screen with a list of your drives. Click "Drive Options," then click the "Format" button to format the drive as NTFS before you click Next and install Windows. Make sure you’ve backed everything up before you reinstall!

That’s all there is to it. The process is much simpler than this long guide would have you believe, and once you’ve gotten the hang of it once or twice it’ll be like riding a bike. All it takes is a few clicks to get a fresh, clean drive formatted for your needs.