Installing an Operating System from an ISO File: Windows 11 with Rufus

This guide shows how to write a downloaded ISO file to a USB drive with Rufus and install Windows 11 on a computer from scratch; it takes about 45–90 minutes depending on the hardware.

1. Before you begin

What you need

• A blank USB drive of at least 8 GB (everything on it will be erased)
• The Windows 11 ISO file (you need roughly 6 GB of free disk space for it)
• Rufus (official site: rufus.ie) and a second, working Windows PC with internet access to write the ISO to the USB drive. Rufus runs only on Windows, so if the computer you want to install on does not start yet, you cannot use it for this step.
• A keyboard and mouse for the target computer, preferably with a wired internet connection

Minimum hardware requirements for Windows 11

Important: The installation may erase the disk. Back up your personal files to an external drive or cloud storage first. On laptops, keep the charger plugged in.

2. Downloading and verifying the ISO file

Download the ISO only from Microsoft's official download page. Files from third-party sites may have been tampered with.

1. Open Microsoft's "Download Windows 11" page in your browser.
2. Under "Download Windows 11 Disk Image (ISO)", choose Windows 11 (multi-edition ISO) and click Download.
3. Select the product language (for example, Turkish), click Confirm, then click 64-bit Download. The download link is valid for a limited time; refresh the page if it expires.
4. When the download finishes, verify that the file is intact. Open PowerShell and run the command below, changing the file path to match your file:

Get-FileHash "$env:USERPROFILE\Downloads\Win11_Turkish_x64.iso" -Algorithm SHA256

5. Compare the SHA-256 value with the one published on the download page for your language. They must match exactly; if not, download the file again.

Tip: Rufus can also download the ISO directly (use the drop-down arrow next to the SELECT button). This guide assumes you have already downloaded it.

3. Creating a bootable USB drive with Rufus

Rufus writes the ISO file to a USB drive in a way the computer can boot from. The program is portable and needs no installation. You need a working Windows PC for this section; if the target computer has no operating system yet, prepare the USB drive on a friend's, workplace or internet café computer.

1. Download the latest version from Rufus's official site (rufus.ie) and run it. If User Account Control asks, click Yes.
2. Plug in the USB drive. Make sure the correct drive is selected under Device; choosing the wrong drive will erase its data.
3. Leave Boot selection as "Disk or ISO image", click SELECT, and choose the Windows 11 ISO you downloaded.
4. Set the options as shown in the table below.
5. Click START. If the "Windows User Experience" window appears, you can click OK with the default choices.
6. Confirm the warning that all data on the drive will be destroyed. When the status bar says READY, click CLOSE.
7. Eject the USB drive using "Safely remove hardware" in Windows.

TPM and Secure Boot note: The "Extended Windows 11 Installation" option in Rufus skips the TPM 2.0, Secure Boot and RAM checks. Installing on unsupported hardware is not recommended by Microsoft and may not receive updates; choose the Standard option on regular computers.

4. Booting from the USB drive (BIOS/UEFI)

The easiest way to start the target computer from the USB drive is to use the boot menu.

1. Plug the prepared USB drive into the target computer and shut it down completely.
2. Turn it on and repeatedly press the key from the table below while the manufacturer logo is displayed.
3. In the list that opens, select the entry that reads "UEFI: USB drive name" and press Enter.
4. If you see "Press any key to boot from USB", press any key. The Windows Setup screen appears within a few seconds.

Keys vary by model and year; also check your computer's manual.

If the USB drive does not appear in the list

• Enter the BIOS/UEFI settings and check that USB boot is enabled.
• For Windows 11, confirm that UEFI mode is on and that Secure Boot and TPM (also called PTT on Intel and fTPM on AMD) are enabled.
• Try a different USB port, preferably a USB 2.0 port at the back of the computer.
• If you changed any settings, save and exit with Save & Exit.

5. Windows 11 installation steps

When the USB boot succeeds, the Windows Setup screen appears. Follow these steps in order.

1. Language and keyboard: Check "Language to install", "Time and currency format" and "Keyboard or input method", click Next, then click Install now.
2. Activation: Enter your product key if you have one. If you do not, or if Windows 11 was already activated on this computer, click I don't have a product key; you can activate Windows later.
3. Edition: Select the edition that matches your license (for example, Windows 11 Home or Pro) and click Next. Choosing the wrong edition can make activation fail later.
4. License terms: Tick "I accept the Microsoft Software License Terms" and click Next.
5. Installation type: For a clean installation, choose Custom: Install Windows only (advanced). Upgrading while keeping your files requires running setup from inside Windows; that option does not work when booted from USB.
6. Disk selection: Choose the disk to install on.

• On a new, empty disk, select Unallocated Space and click Next; Windows creates the required partitions itself.
• On a previously used disk, once you have a backup, select each old partition and click Delete, then select the resulting Unallocated Space and click Next.
• If there are several disks, check the sizes to be sure you pick the right one.

6. After the installation

• Install all updates from Settings > Windows Update and restart if required.
• Check the version under Settings > System > About and the license status under Activation.
• In Device Manager, confirm there are no devices with a warning icon; get missing drivers from the computer manufacturer's site or Windows Update.
• Test Wi-Fi, sound, screen brightness and USB ports.
• Make sure Windows Security (virus and threat protection, firewall) is on.
• Restore your backed-up files and install the apps you need.
• Keep the USB drive for future use, or return it to a normal drive with Rufus or Windows' format tool.

7. Common problems