How To Erase And Format A Hard Drive

How To Erase And Format A Hard Drive

Whether 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.

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 (such as Windows, Mac OS X and Linux) use different file systems to organise and store data, and 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 read NTFS-formatted drives, but not write to them — unless you have a third-party driver like NTFS-3G installed.
  • FAT32: 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 such as movies.
  • ExFAT: ExFAT is less commonly used, and 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 — such as 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 (and also 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 see a notification when it’s done (it should only take a few seconds).

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 quite the same amount of free space as it does on the box. This is because computers measure space differently to the numbers used when they are marketed, so you’ll never get that exact same number, at least on Windows.


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 Your Computer’s Main Hard Drive

If you want to erase your computer’s main hard drive, things become a little more complicated. 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. After you’ve done that, 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 will be as easy as riding a bike. All it takes is a few clicks to get a fresh, clean drive formatted for your needs.

Lifehacker 101 is a weekly feature covering fundamental techniques that Lifehacker constantly refers to, explaining them step-by-step. Hey, we were all newbies once, right?

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