How long does it take to reinstall Windows?
Generally, the reinstall of Windows takes between 1 and 5 hours. However, there is no exact time for how long it can take to install Microsoft Windows and can vary based on the below factors.
Upgrade vs. Full install
A Windows "Upgrade" from a previous installation takes longer than a clean install. Upgrades use all the current data in the current operating system, instead of just replacing all the files. Many are upgraded along with the Installation to keep all your current settings and data.
For many of the hardware devices installed and connected to your computer, additional drivers and software need to be installed. Although Windows can detect and install the software required for many hardware devices, which can increase the overall installation time, it's possible that not all hardware will be detected. It'll be up to the user after the installation of Windows to install the remaining software and drivers for their hardware.
Finally, you'll need to install all available Windows updates after installing Windows. With older versions of Windows there can be dozens of updates and service packs that need to be installed to finalize the Windows installation. Depending on your Internet speed, how many updates are needed, and how many times you need to reboot can cause this final step to add several hours to the initial install time.