Can I upgrade my windows 8.1 to windows 10 for free?

Clean installation using a Windows 10 bootable USB drive This is the most thorough method for upgrading Windows 8.1 to Windows 10.

A clean installation involves completely wiping the drive partition where Windows 8.1 is installed and installing Windows 10 from scratch using a bootable USB drive. This eliminates any old system clutter or corrupted files, but requires you to back up and manually restore your data and reinstall all your applications afterward.

Step 1: Create a Windows 10 bootable USB using the official Microsoft tool.

Step 2: Restart your Windows 8.1 PC. You will need to access your PC's boot menu (often by pressing a key like F2, F12, Esc, or Del immediately after powering on) and select the USB drive as the boot device.

Step 3: The Windows 10 Setup will begin. Select your language and keyboard preferences, and click Next.

Step 4: On the "Which type of installation do you want?" screen, select "Custom: Install Windows only (advanced)."

Step 5: Select the primary partition where Windows 8.1 is currently installed and click Delete (this is why you must have a backup!). Then, select the resulting unallocated space and click Next to install Windows 10.

Windows 10 will install. After the final reboot, follow the on-screen prompts to set up your account and preferences.