How to Format a Computer

This article provides instructions on how to completely erase all data on a Windows or macOS computer, including the operating system. Formatting a computer means deleting all data from the hard drive and reinstalling Windows or macOS to start fresh. This process is useful when your computer isn't functioning properly, or if you want to sell it and prevent the buyer from recovering any data. Fortunately, both Windows and macOS come with easy-to-use formatting tools that simplify the process.

Backup your data. While formatting a Windows 10 computer is straightforward, the changes are permanent – you will erase all applications, settings, and personal files, and reinstall Windows. Fortunately, you can easily back up the files you want to keep using the built-in tools on your computer. Learn how to back up files on Windows 10 to create a backup on a DVD, CD, external hard drive, or cloud service.

Click on Update & Security. This option is represented by an icon with two curved arrows.

Select Recovery from the left-hand panel.

Click the Get started button beneath the "Reset this PC" option. This is the first button on the top right of the panel.

Click on Remove everything. This is the second option on the blue screen.

Click on Remove files and clean the drive. This is the second option. You need this to format the hard drive – the other option only removes the OS and reinstalls it without formatting the drive.

• Wiping the drive is essential if you plan to sell or give away the computer, as it ensures the deleted files are harder to recover. If you plan to continue using the computer, you can select Just remove my files to skip the format step.
• A more thorough way to wipe the hard drive is using third-party data erasing tools like DBAN (Darik's Boot and Nuke). Ensure you have a Windows 10 recovery disk or DVD if using such tools, so you can reinstall the OS. Learn more about secure hard drive erasure techniques for additional details.

Click on Next on the warning screen. If you see a message indicating that your computer has been upgraded to Windows 10, it means that reinstalling Windows prevents you from reverting to the previous version.

Click Reset to begin formatting your computer. The process may take a while depending on the size and speed of your hard drive (from a few minutes to several hours).

• If you are using a laptop, make sure it is plugged into a power source to prevent any interruptions during the formatting process.

Click Continue when the formatting process is completed. Your computer is now formatted. To reinstall Windows, simply follow the on-screen instructions.

Backup your data. Since formatting your computer will erase all files and settings, it's important to back up your data beforehand. Check out how to back up your Windows PC to quickly save your files before proceeding.

• If your computer originally ran Windows 8 instead of Windows 8.1, formatting and reinstalling will revert the device to Windows 8. Don't worry though – you'll still have the opportunity to upgrade your computer to Windows 8.1 for free after installation.

Keep the cursor at the bottom-right corner of the screen. This action will open the Charms menu.

Click on Change PC Settings (Adjust your computer's settings). This option is located at the bottom of the menu.

Click on the Update and recovery (Update and restore). This option is located near the bottom-left corner of the left panel.

Click on the Get started (Begin) option beneath "Remove everything and reinstall Windows". This option is located in the middle of the right panel. Be sure not to accidentally click on "Get started" below another option, as there are multiple choices here.

Click on Next (Continue). This action confirms that you want to erase all files, apps, and settings from your computer.

Select the drive you wish to format. If you only want to format the drive where Windows 8 is installed, choose Only the drive where Windows is installed. To format the entire disk on the computer, select All drives.

Click on the Fully clean the drive (Erase all data on the drive). This option (second in the list) ensures the entire drive is formatted.

• If you're still using the computer and don't mind if others access deleted files, you can click on Just remove my files. This way, the drive will not be formatted.
• A more thorough method for wiping the drive is using third-party data-wiping tools like DBAN (Darik's Boot and Nuke). DBAN and similar tools ensure that deleted file fragments are unrecoverable, which is helpful if you're selling or giving away the computer. Just make sure you have a way to reinstall Windows afterward. Check how to wipe a hard drive for more details.

Click on Reset (Reset) to format the computer. Depending on the size and speed of the hard drive, this process may take some time (from a few minutes to several hours).

• If you're using a laptop, make sure it's plugged into a power source to prevent interruptions during the formatting process.
• Once the computer is formatted, it will reboot and begin reinstalling Windows. Follow the on-screen instructions if you wish to proceed.

Back up your data. Formatting your Mac will erase all of your data, so be sure to back up everything you want to keep. You can check how to back up your Mac to learn how to save files to Time Machine or iCloud.

Turn on your Mac and press ⌘ Command+R. If your Mac is already on, restart the device and press these keys as soon as the machine starts. This will boot your Mac into Recovery Mode.

• You can release the keys once you see the Apple logo or the startup screen.

Select Disk Utility (Disk Utility). This is the last option in the "macOS Utilities" window.

Click the View (View) menu. This option is found in the top menu bar of the screen.

Click Show All Devices (Show all devices). All drives connected to your Mac will appear in the left pane.

Select the disk you wish to format. For example, if you want to format the disk that contains macOS, choose the first disk in the list (under 'Internal').

Click the Erase (Erase) button. This option is located above the center of the window.

Select the formatting options.

• Name: Enter a name to identify the hard drive.
• Format: Keep the default format for the internal drive as APFS, unless you have a specific reason to choose otherwise.
• Scheme: Select Choose GUID Partition Map.

Click Erase (Erase) to format the disk. You will be prompted to verify your Apple ID or password. Once the disk is erased and formatted, you will be returned to the Disk Utility list.

• If your Mac has multiple disks, you can format them now using Disk Utility.

Close Disk Utility. You can do this by clicking the red circle at the top left corner of the window.

• If you wish to reinstall macOS on this drive, restart your computer in Recovery Mode by pressing Control + R when the computer starts, and select Reinstall macOS to reinstall from scratch, or Restore From Time Machine Backup if you have backed up the operating system to Time Machine.