How to Back Up Files Before Upgrading Windows

Updated 4 November 2026 · Standard formula, shown below

Upgrading Windowsâ€”whether to a new feature update or a fresh installâ€”carries a small but real risk of data loss. This guide walks you through backing up your important files so you can restore them if anything goes wrong. You’ll learn what to copy, where to put it, and how to verify the backup before you start the upgrade.

What You’ll Need

An external hard drive, USB flash drive (at least 16 GB, preferably larger), or access to a cloud storage service (like OneDrive, Google Drive, or Dropbox).
Your Windows login credentials (to access user folders).
About 30â€“60 minutes, depending on how much data you have.

Step-by-Step

Identify what to back up. The most important files are in your user profile: Documents, Pictures, Videos, Music, Downloads, Desktop, and any saved game data or application settings. Also consider email (if using a desktop client like Outlook), browser bookmarks, and any project files stored outside the default folders.
Choose a backup destination. Use an external drive with enough free space (check total size of your user folders first) or a cloud service with sufficient storage. For large amounts of data, an external drive is faster and more reliable.
Connect the external drive or sign in to cloud storage. If using a USB drive, plug it in and wait for Windows to recognize it. If using cloud storage, install the desktop app and sign in.
Copy your user folders. Open File Explorer, go to C:\Users\[YourUsername], and select the folders you want to back up. Right-click and choose Copy, then paste them into the backup location. Alternatively, use drag-and-drop. For cloud storage, you can also use the sync folder (e.g., OneDrive folder) to copy files into.
Back up application settings and game saves. Many apps store settings in %AppData% and %LocalAppData%. You can copy these folders, but they can be large. For games, check if they use cloud saves (e.g., Steam, Epic) or manually copy save files from the game’s folder. If you’re not sure, a full system image is safer (see step 7).
Create a system image (optional but recommended). Windows has a built-in tool: go to Control Panel > Backup and Restore (Windows 7) > Create a system image. Choose your external drive and follow the prompts. This creates a complete snapshot of your system, including Windows, apps, and files.
Verify the backup. After copying, open a few files from the backup location to ensure they open correctly. Check file sizes and counts against the originals. For system images, the tool will verify automatically, but you can also check the image file size.
Eject the external drive safely. Right-click the drive in File Explorer and choose Eject before unplugging it.
Proceed with the upgrade. Once your backup is verified, you can start the Windows upgrade. Keep the backup drive connected or cloud sync active until the upgrade completes and you’ve confirmed everything works.

Common Mistakes

Only backing up to the same disk. Copying files to another folder on the same drive does not protect against drive failure or upgrade errors that wipe the disk.
Forgetting hidden or less obvious files. App settings, browser profiles, and game saves are often missed. Use the system image if you’re unsure.
Not verifying the backup. A backup that can’t be read is useless. Always open a few files after copying.
Using a USB drive that’s too small. If you run out of space mid-copy, you may end up with an incomplete backup.
Assuming cloud sync is automatic. If you copy files into a cloud folder but the app isn’t running, they may not upload. Check the cloud status icons.

Tips

Use File History. Windows has a built-in File History feature that can back up your libraries to an external drive. Set it up before the upgrade for continuous protection.
Compress large folders. If you’re copying to a cloud service with limited space, zip large folders (right-click > Send to > Compressed folder) to reduce size.
Keep a list of installed programs. After the upgrade, you’ll need to reinstall apps. Use a tool like winget or just take a screenshot of your Start menu.
Do the backup a day before. This gives you time to notice any missing files and re-copy them.
Use a new folder on the external drive. Label it with the date (e.g., Backup_2025-04-10) to avoid confusion with older backups.

Troubleshooting

Backup fails with “file in use” error. Close any programs that might be using the file. If it’s a system file, you may need to run the copy as administrator or use File History.
External drive not recognized. Try a different USB port, restart your PC, or check Disk Management (right-click Start > Disk Management) to see if the drive appears. If it does but has no letter, assign one.
Cloud upload is stuck. Check your internet connection, pause and resume the sync, or restart the cloud app. Ensure you have enough cloud storage.
System image creation fails. Make sure the external drive is formatted as NTFS (not FAT32) and has enough free space. You may need to disable third-party antivirus temporarily.
After upgrade, files are missing. Check the Windows.old folder on the system drive (if the upgrade created one). It contains previous files and can be accessed for up to 10 days after upgrade.

Frequently Asked Questions

Do I really need to back up if I’m just doing a Windows Update?

For minor updates, the risk is low, but for feature updates (like 23H2 to 24H2) or a clean install, the risk is higher. Backing up is cheap insurance.

Can I back up to the same external drive I use for other things?

Yes, but create a separate folder for your backup to keep it organized and avoid accidentally deleting it.

How long does a backup take?

It depends on the amount of data and the speed of your drive or internet connection. A few GB might take minutes; 100+ GB could take hours.

What if I don’t have an external drive or enough cloud storage?

You can use a USB stick (if it’s large enough), a network drive, or even burn files to DVDs. For a small amount of data, a USB stick is fine.

Is a system image better than copying files?

A system image is a complete snapshot, so you can restore your entire system, including apps and settings. It’s more thorough but requires more space and time. For most users, copying personal files is sufficient.

Can I back up only my Documents folder?

Yes, if that’s all you care about. But remember to include Desktop, Downloads, and any other folders where you store files.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.