Detailed Screenshots + Complete Guide to Essential Initial Setup for a Clean Windows 11 Installation (Verified December 2025)

As of December 2025, this is the latest version of Windows 11 25H2.

1. Download the Windows disk image (ISO)
2. Create a Windows installation USB
3. Select the clean install option for Windows
4. Perform the initial Windows setup

I’ll walk you through each step in sequence.
I’ve included detailed screenshots of every step so beginners can follow along immediately.

Don’t overthink it.
Just follow along, and anyone can install a clean new copy of Windows.

Summary of Microsoft’s Official Guide

First, Microsoft provides a brief explanation of how to perform a clean installation of Windows on the webpage below.
https://www.microsoft.com/en-us/windowsinsider/cleaninstall

The main points of Microsoft’s official clean installation guide are:

1. Create a Windows 11 installation USB drive (minimum 8GB)
2. Back up existing data on your PC (WARNING!! Formatting will delete all data!!)
3. Boot your PC from the USB drive
4. Proceed with Windows 11 installation from the USB drive

See? It’s easy!
I’ll explain it along with my own setup tips.
Follow along step by step while looking at the screenshots below~

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Download Windows 11 Disk Image (ISO)

Access the Windows 11 Download Page

First, prepare a USB drive. You will need a USB drive with at least 8GB of storage.
All data on this USB drive will be deleted.

Download the Windows image ISO file from the Windows download page.

Searching for keywords like Windows 11 download on Google will bring up the official Microsoft website.
Alternatively, clicking the URL below will open the download page.
https://www.microsoft.com/en-us/software-download/windows11

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Selecting the Windows 11 Disk Image (ISO)

This is NOT the download for the Windows 11 Installation Assistant!!!
Scroll down slightly further on the page to find the Disk Image (ISO) download.

Select Windows 11 (Multi-Edition ISO for x64 devices) and click Download now.

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Windows 11 Language Selection

The language selection screen will now appear.
Select your preferred language and click the OK button.

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Start Downloading Windows 11

You’re all set.
Click the 64-bit download button to begin downloading.

The file size is about 7GB, so downloading it takes some time.
Usually, download speeds are good, so it takes about 10 minutes to download everything,
but occasionally, when the MS servers are slow, it can take over 30 minutes.

Please wait a moment until the ISO download completes.
Once you’ve downloaded the ISO file, we’ll now create the bootable USB.

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Creating a Windows 11 Installation USB

Download Rufus

I do not recommend using the Windows 11 Installation Assistant provided by Microsoft.
I’m not sure why, but when you create a bootable USB using the Installation Assistant, it often doesn’t work properly.
After wasting time multiple times, I now only use Rufus.

https://rufus.ie/en/#download
Rufus is a free tool for creating bootable USB drives.
It can create bootable USB drives not only for Windows but also for Linux and other operating systems.

In particular, I’ll explain an additional feature that makes creating a Windows bootable USB even more convenient.

Clicking Download in the top menu displays the download list.
I prefer the portable version of Rufus.
It’s convenient because no separate installation is required—just run the file and you can use it immediately.

Just download it and run it right away.
When you run it, a configuration file will be created, but don’t worry about it. Just delete everything after you’re done using it.

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Running Rufus

When you first run Rufus, it will ask if you want to check for updates. It doesn’t matter which option you choose.
I don’t feel the need to check for updates, so I select No.

The Rufus window will open as shown in the screenshot below.
It will automatically detect the USB drive connected to your PC.

Important note: Make sure to remove any other USB drives from your PC to avoid mistakes.
Only connect one USB drive to the PC that you don’t mind completely erasing for installing Windows.

Selecting the wrong USB could accidentally wipe all your data~
You can verify it’s the correct USB by checking its capacity.
Any USB with over 8GB capacity will work.

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Selecting the Windows 11 ISO in Rufus

Now click the Select button and choose the downloaded disk image (ISO).
Rufus will then recognize the Windows ISO and automatically configure all options.

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Rufus Additional Options and Creating an Installation USB

Now, when you click the Start button, the following options selection window will open.
This is the convenient feature I mentioned earlier.

Microsoft now encourages you to log into Windows using a Microsoft online account.
But I find that inconvenient, so I always install using a local account (the old way).

Selecting an option here will automatically bypass the TPM 2.0 requirement or disable the use of an online Microsoft account.

Now, click OK to start creating the bootable USB.
It’s really easy~

A warning will appear again stating that all existing data on the USB will be deleted.
Double-check that this is indeed the USB you inserted, then click OK~

Then, as shown in the screenshot below, you can see the current progress status in the status section.

Copying the entire ISO to the USB may take a little time.
This can vary depending on the USB speed, typically taking a few minutes or over 10 minutes.

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Windows 11 Installation USB Complete

Once the installation USB is complete, the screen will change as shown below.
The USB name at the top will be changed to the Windows installation USB name,
and the status section will display Ready with a green status bar filled.

Now click Close to exit Rufus.

Since Rufus is no longer needed, you can delete the Rufus executable file you downloaded.

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Restarting the Computer (Rebooting)

Booting from USB via Windows Advanced Startup Options

Now we’ll proceed with the full Windows 11 installation.

It’s time to say goodbye to your existing Windows.
You must now reboot the computer, but it’s crucial to hold down the Shift key while restarting Windows.

1. After clicking the Windows Start button
2. click the power button and
3. while holding down the Shift key on the keyboard with your left hand,
4. click Restart.

Keep holding the Shift key down to ensure it is recognized correctly.
A blue screen with the message Please wait a moment will appear; you can keep holding Shift during this.
Once you see the blue screen as shown below, you can release the Shift key.

The Windows Advanced Startup screen is now open.
You can boot from USB using the Use a device option.
Click Use a device with the mouse or navigate to it using the arrow keys and press Enter.

Then it will appear as shown in the screen below; I have erased the text.
You should see the Windows installation USB you created earlier here.
Click the Windows installation USB item or navigate to it using the arrow keys and press Enter.

Alright~ Now it’s time to get started for real.
Goodbye, old Windows~~

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Windows 11 Clean Installation

When your computer starts up and the following message appears on a black screen,
press any key on your keyboard immediately.
(If you don’t press any key, it will boot into your existing Windows installation. If that happens, hold down the Shift key and reboot.)

The Windows logo briefly appears as shown below…

Alright, the Windows installation will now begin.
The Language Selection screen will appear; leave it as is and click Next.

Now the Keyboard Settings Selection appears.
There is nothing specific to change. Click Next.

When the Select Installation Options screen appears,
with the Install Windows 11 option selected,
check the box next to I agree to delete everything, including files, apps, and settings.
Then click Next.

When the Product Key input screen appears, enter the product key you have.
If you don’t have a product key, click I don't have a product key. below.
Even without entering a product key, you can still use Windows, though it may be slightly inconvenient.

The screen for selecting the Windows version where you entered the product key will not appear.
If you don’t have a product key, a screen will appear asking you to choose which Windows version to install.

In fact, you can select any option.
Later, when you enter the product key into Windows, the Windows version will automatically change to match that product key.

Here, we will proceed by selecting the default choice, Windows 11 Home.

Older PCs may fail to meet hardware security requirements, resulting in the following message.

If you selected the option to remove requirements for 4GB or more RAM, Secure Boot, and TPM 2.0 when creating the installation USB with Rufus earlier,
the installation will proceed without displaying the warning below.

If this warning appears, you can continue installing Windows 11 on older computers by modifying the registry as described in the post below.
(If you modified the registry, you don’t need to reboot. Simply go back to the Windows version selection screen and click Next again to continue the installation.)

When the Terms and Conditions screen appears, click Agree to proceed to the next step.

Select Windows 11 Installation Disk

Now for the important part.

You must pay close attention to this part.

Especially if your computer has multiple SSDs or hard drives connected, you must be extremely careful.

As shown in the screenshot above, if there is only one disk number, such as Disk 0,
it means there is only one SSD (or HDD).
In this case, there is no difficulty.

However, if there are multiple disk numbers, such as Disk 0 and Disk 1,
it means there are multiple SSDs (or HDDs).
At this point, you must be extremely careful and select the SSD where Windows is already installed.

While Disk 0 is usually the disk with Windows installed,
sometimes Windows is installed on Disk 1 or Disk 2 instead of Disk 0.

How to Verify the Disk Where Windows Is Installed

• Disk 0 (or Disk 1) refers to a single SSD.
• Check the total size of that disk to see if it matches the capacity where Windows was previously installed.
• The Windows installation disk creates several partitions ranging from tens of megabytes to about 500MB, labeled as Recovery, System, MSR (Reserved), as shown in the screenshot above.
• Therefore, if you find partitions labeled Recovery, System, MSR (Reserved)`, that disk is the SSD used for Windows.

Now, once you’ve confirmed the disk for Windows installation, select each partition on that disk one by one and click the Delete Partition button above.
As each partition is deleted, it changes to Unallocated Space and merges together, as shown in the screenshot below.

Deleting all partitions on the disk to be installed will consolidate Disk 0 (or Disk 1) into unallocated space, as shown in the screenshot below.
Select the disk and click the Next button to proceed with the installation.

All preparations are finally complete.
When the installation ready screen appears, click the Install button to begin the installation.

The following screen will appear as the installation proceeds, and the system will automatically reboot several times.

Thanks for sticking with me this far~~

Closing Remarks

Installing Windows might have seemed daunting at first,
but just taking on this challenge and seeing it through to the end is truly impressive.

Once you understand it, installing Windows isn’t particularly difficult.
If you take it step by step, it will naturally become second nature,
and before you know it, you’ll find yourself installing Windows with ease.

Having completed this process, you now possess the strength to tackle anything on your own without fear.

Goodbye~