Generally, reinstalling Windows takes between 1 and 5 hours. However, the timing may vary based on the factors listed below.

System hardware

The speeds of your CPU, optical drive, and hard drive, and how much RAM your computer dictates Windows’ installation time. A faster CPU and more RAM can reduce the time it takes to install Windows. A computer with an SSD can install Windows faster than a computer with a standard hard drive.

Upgrade vs. full install

A Windows “upgrade” from a previous installation takes longer than a clean install, up to an hour. Upgrades use all the data in the current operating system instead of replacing all files. Many are upgraded with the installation to keep all your current settings and data.

Driver installation

For many of the hardware devices installed on and connected to your computer, additional drivers and software are needed. Although Windows can detect and install most of the software required for many hardware devices, some may still need to be done manually. It’s up to the user after the installation of Windows to install the remaining software and drivers for their hardware.

Windows updates

Finally, you need to install all available Windows updates after installing Windows. With older versions of Windows, there are a lot of updates and service packs that need to be installed to finalize the Windows installation. Depending on your Internet speed, the number of updates, and how many times the computer reboots can cause this final step to take several hours to complete.

  • How to update a Microsoft Windows computer.
  • Microsoft Windows help and support.