Overview
You do not always need a bootable USB drive or DVD to install Windows 10. If you already have the Windows 10 ISO on your hard drive, you can launch setup directly from within Windows or from the recovery environment. This is handy when you lack a spare USB drive or want to reinstall quickly. This guide covers both the in-Windows method and the advanced startup method.
Key Takeaways
- You can start Windows 10 setup straight from an ISO stored on your drive.
- Running setup from inside Windows supports upgrade and repair installs that keep your files.
- A true clean install of the same drive still requires booting from separate media or the recovery environment.
- Always download the official ISO from Microsoft before you begin.
Note: Download the Windows 10 ISO only from Microsoft’s official software download page to guarantee an untampered, genuine image.
Method 1: Run Setup From Inside Windows
This is the simplest route and works well for repairs and in-place upgrades that preserve your apps and files.
1. Open File Explorer and locate your downloaded Windows 10 ISO file.
2. Right-click the ISO and choose Mount — Windows creates a virtual DVD drive.
3. Open that virtual drive and double-click setup.exe.
4. Follow the wizard, choosing whether to keep personal files and apps, then let the installation complete.
Tip: An in-place upgrade install is an excellent way to repair a damaged Windows 10 system without losing your data.
Method 2: Install From Advanced Startup
For a clean install you can extract the ISO contents to a folder on a non-system partition and launch setup from the recovery environment.
1. Extract the ISO contents to a folder on a drive or partition other than C:.
2. Go to Settings > Update & Security > Recovery and click Restart now under Advanced startup.
3. Choose Troubleshoot > Advanced options > Command Prompt.
4. Navigate to the folder containing the extracted files and run setup.exe from there.
5. Proceed through the installer to complete the clean installation.
Warning: A clean install erases the contents of the target partition. Back up all important files before you start, because this step cannot be undone.
Troubleshooting
Problem: The Mount option is missing from the right-click menu.
Solution: Make sure the file has a .iso extension and that no third-party disc tool has taken over ISO handling; you can also open the ISO with File Explorer set as the default.
Problem: Setup reports it cannot run from the current location.
Solution: Move the extracted files to a folder path without special characters and run setup.exe as an administrator.
Problem: You cannot clean-install onto the same system drive from within Windows.
Solution: Use the advanced startup or a bootable USB drive, since Windows cannot format the partition it is currently running from.
Problem: Installation fails partway with a generic error.
Solution: Verify the ISO download integrity, free up disk space on the target partition, and temporarily disconnect other external drives.
Conclusion
Installing Windows 10 from a hard-drive ISO is a convenient alternative when you have no removable media on hand. Use the in-Windows method for upgrades and repairs, and the recovery-environment method when you need a fresh clean install.
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