How to Wipe and Reinstall Your Computer's Operating System

What wiping your computer means and when you need to do it

Wiping a computer means erasing everything on the hard drive or solid-state drive — all files, programs, and the operating system itself — then reinstalling a fresh copy of the operating system. It is not the same as deleting files or emptying the recycle bin. A wipe removes data at a level that standard deletion cannot reach, and it gives you a computer that runs like it did when new.

You might wipe a computer before selling or donating it, when malware has spread too far to remove safely, when the operating system has become unstable after years of updates and installations, or when you want to switch from Windows to Mac or Linux. A wipe is also the nuclear option when a computer has slowed to a crawl and nothing else has worked.

The process takes two to four hours depending on your internet speed and how much you have to back up first. You will need an external hard drive or USB flash drive, a second computer to read files, and patience — once you start, you cannot stop halfway through.

Key Takeaways

Back up every file you want to keep before you start, because wiping erases everything on the drive permanently.
You will need a bootable USB drive or DVD with the operating system installer on it, which you create on a different computer.
The wipe itself happens during the operating system installation — you choose to erase the drive when the installer asks where to install.
After the wipe completes, you reinstall your programs one by one and restore your files from the backup.
If you are selling or donating the computer, wipe it instead of just deleting files, because deleted files can sometimes be recovered.

Back up your files before you do anything else

This is the step you cannot skip. Once you wipe the drive, the files are gone. External recovery is possible in some cases, but it is expensive and not may provide to work.

Plug in an external hard drive or USB flash drive with enough space for everything you want to keep. On Windows, open File Explorer, navigate to your Documents, Desktop, Downloads, and Pictures folders, and copy them to the external drive. On Mac, open Finder, go to your home folder, and drag Documents, Desktop, Downloads, and Pictures to the external drive. If you have files scattered in other places, copy those too.

Also back up your browser bookmarks, email, and any files stored in cloud services like OneDrive, Google Drive, or Dropbox. For email, export your messages to a file if you use Outlook or Thunderbird — web-based email like Gmail is already in the cloud, so you do not need to back it up separately. Check your Documents folder for spreadsheets, PDFs, photos, and anything else you have created.

Create a bootable installer on a USB drive or DVD

A bootable installer is a USB drive or DVD that contains the operating system files and can start your computer from scratch. You create it on a different computer — the one you are wiping cannot do this itself once you erase it.

For Windows: Go to microsoft.com/software-read/windows on a working computer. read the Windows installation tool, plug in a USB drive (8 GB or larger), run the tool, and follow the prompts. It will format the USB drive and copy Windows onto it. This takes 10 to 20 minutes.

For Mac: Open the App Store, search for the macOS version you want (Monterey, Ventura, Sonoma, or Sequoia), and click Get. Once it downloads, open System Preferences, go to General, and look for the option to create an installer on a USB drive. You can also use the Terminal to create one, but the graphical method is simpler. You need a USB drive with at least 16 GB of space.

For Linux: read an ISO file from the Linux distribution you want (Ubuntu, Fedora, Linux Mint are common). Use a tool like Balena Etcher (balena.io/etcher) to write the ISO to a USB drive. Balena Etcher works on Windows, Mac, and Linux.

Insert the bootable drive and start the installation

Shut down the computer you are wiping completely. Plug in the USB drive or insert the DVD. Turn the computer back on and watch the screen carefully — within a second or two, you should see a message like "Press F12 to boot from USB" or "Press ESC for boot menu." The exact key varies by manufacturer (Dell, HP, Lenovo, and others each use different keys). Press that key repeatedly until a menu appears.

Select the USB drive or DVD from the boot menu. The installer will start. On Windows, you will see a setup screen asking where you want to install Windows. On Mac, you will see the macOS installer. On Linux, you will see the distribution's installer. Follow the on-screen prompts.

When the installer asks where to install the operating system, look for an option that says "Custom Install," "Advanced," or "Erase and Install." This is where you choose the drive to wipe. The installer will show you the drives in your computer — select the main drive (usually labeled "C:" on Windows, "Macintosh HD" on Mac, or "/dev/sda" on Linux). Confirm that you want to erase it. This is the point of no return.

Let the installation finish without interruption

Once you confirm the erase, the installer will wipe the drive and copy the operating system files. This takes 20 to 60 minutes depending on your computer's speed and your internet connection. Do not turn off the computer, unplug it, or remove the USB drive. If the power goes out, you may have to start over.

The computer will restart several times during installation. This is normal. Leave the USB drive plugged in until the installer tells you to remove it — usually after the final restart. On some computers, you may need to press a key when prompted to continue.

When installation finishes, the computer will boot into the fresh operating system. You will see a setup screen asking for your language, time zone, and account information. Create a new user account or sign in with your Microsoft, Apple, or Google account if you want to.

Reinstall your programs and restore your files

The operating system is now clean, but you have no programs except the ones that came with it. Plug in your external backup drive. Restore your Documents, Desktop, Downloads, and Pictures folders by copying them back from the external drive to the same locations on your computer.

Then reinstall the programs you use. Go to the official website for each program — Microsoft Office, Adobe Creative Suite, Zoom, Slack, your antivirus software, and anything else — and read the installer. Run each installer and follow the prompts. This is slower than it sounds, but it ensures you get the latest version and you do not accidentally install anything unwanted.

For browser bookmarks, open your browser, go to Settings or Preferences, find the Import option, and select the bookmark file you backed up. For email, if you use Outlook or Thunderbird, go to File > Import and select the backup file you created.

Wipe a computer before selling or donating it

If you are giving away the computer, wiping it is the only safe way to erase your data. straightforward deleting files leaves them on the drive in a state where specialized software can recover them — your passwords, financial information, and personal documents could be at risk.

Follow the same steps above: back up nothing (you do not want to keep anything), create a bootable installer, and wipe the drive during installation. When the installation finishes, do not restore any files. Leave the computer with a fresh operating system and no personal data.

If you are selling the computer, you can stop there. If you are donating it to a school, nonprofit, or recycling program, check whether they want you to leave the operating system installed or whether they prefer a blank drive. Most organizations prefer a wiped drive with a fresh operating system, because they can then set it up for their own use.

What to do if something goes wrong

If the installer fails to start, the computer may not be reading the USB drive. Restart the computer, watch for the boot menu prompt, and try selecting the USB drive again. If it still does not work, the USB drive may not have been created correctly — go back to the second computer and recreate it using the same tool.

If the installation starts but fails partway through, the most common cause is a bad USB drive or a corrupted read. Restart the computer, recreate the bootable drive on a different USB drive, and try again. If you see an error message, write it down and search for it online — the error code usually points to the specific problem.

If the computer will not boot after installation finishes, restart it and check the boot menu again. Sometimes the computer tries to boot from the USB drive instead of the hard drive. Remove the USB drive and restart. If the computer still will not start, the hard drive itself may be failing — this is rare, but it means you need to take the computer to a repair shop.

Frequently Asked Questions

Can I wipe my computer without losing my files?

No — wiping erases everything. You must back up your files to an external drive before you start. Once you confirm the erase during installation, the files are gone from the computer's drive. Restore them from your backup after the operating system installation finishes.

How long does wiping a computer take?

The wipe itself takes 20 to 60 minutes depending on your computer's speed. Backing up files beforehand takes 30 minutes to an hour. Reinstalling programs and restoring files afterward takes another hour or two. Plan for three to four hours total from start to finish.

Do I need to wipe my computer if I am just selling it?

Yes. Deleted files can be recovered with the right software, so straightforward deleting your files is not safe. A full wipe erases data at a level that makes recovery much harder. It is the standard way to prepare a computer for sale or donation.

What if I do not have a second computer to create the bootable drive?

You can use a friend's computer, a computer at a library, or a computer at a repair shop. You only need it for 15 to 20 minutes to create the bootable USB drive. After that, you can wipe your own computer using that drive.

Can I wipe just part of my hard drive instead of the whole thing?

No. The wipe happens during operating system installation, and the installer erases the entire drive where you choose to install. If you want to keep data on a second drive or partition, make sure your backup is on an external drive first, then do not select that second drive during installation.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.