If you can't install Windows 10 directly onto your PC - either because you don't have space for the large file, or because you're encountering errors in the installation process - then it's possible to install Windows 10 from a USB stick by creating a USB copy of the installation files.
The process requires a little patience, but it isn't too difficult to follow. If you have lots of files and programs on your PC, then it's worth performing a full system backup first, just in case anything goes wrong with the installation process.
See our guide to creating a backup of your PC
Get the Windows Media Creation Tool
Download Microsoft’s Media Creation Tool (which downloads Windows 10) from Microsoft's website. Choose 32-bit or 64-bit, depending on your system – see our guide on how to check your system properties.
Once downloaded, double-click the tool’s exe file. Tick Create installation media for another PC then Next. Select the Edition that matches your current OS (eg if you have Windows 7 Home Premium, choose Windows 10 Home). Under Architecture, choose 32-bit or 64-bit.
Create a Windows 10 installation USB
Click Next and you’ll be asked whether you want to create a USB flash drive (you’ll need to insert one with 4GB or more free space) or an ISO file, which you can turn into an installation DVD. Choose the USB option and click Next.
Select your USB drive from the list and click Next. You’ll then need to wait while Windows 10 downloads.
Start the Windows 10 upgrade
When finished, navigate to the USB drive and double-click setup.exe to begin the Windows 10 upgrade process. Follow all the on-screen prompts until you see a message saying Installing Windows 10.
As soon as your computer restarts, remove the USB drive then follow the remaining prompts to complete the installation.