How to Install Windows from Scratch: Complete Guide
A complete guide to formatting and installing the operating system step by step without losing your important data.
First of all: a clean install erases all the content on the disk you install onto. Make a backup of your important files before starting.
Step 1: create the installation USB
- First check the Windows 11 requirements if you are going to install this version.
- Go to Microsoft's official Windows downloads page.
- Download the "Media Creation Tool".
- Run it, accept the terms, and choose "USB flash drive" as the media (you need a USB stick of at least 8 GB, which will be completely erased).
Step 2: boot from the USB
- Plug the USB into the machine where you are going to install.
- Turn on the machine and press the quick boot key (F12, Esc, or another depending on the manufacturer) to choose to boot from the USB instead of the disk.
Step 3: the installation wizard
- Choose language and keyboard layout → Next → "Install now".
- If you have a digital licence linked to your account or to the motherboard, click "I don't have a product key" — it will activate on its own once you connect to the internet.
- Choose the drive to install onto (this is what gets erased).
- Wait for it to finish (20-45 minutes depending on your hardware).
Tip: before starting, also create a separate recovery USB if you have another USB stick available — it will come in handy if something goes wrong later on.
Frequently asked questions
Do I need a product key to install Windows?
Not always — if your licence is digitally linked to your Microsoft account or to the motherboard, Windows activates automatically once you connect to the internet, with no need to type any key manually.
How long does a full installation take?
Between 20 and 45 minutes in most cases, depending on whether your disk is an SSD or HDD and on your USB's speed.
Do I lose all my files when installing from scratch?
Yes, it is a clean install that erases the content of the target disk — that is why it is essential to back up what matters before starting.