What you need before you start
Installing Windows on a new PC requires three things: a Windows installation file (usually on a USB drive), a product key or digital license tied to your Microsoft account, and another working computer to create the installation media. If your PC came with Windows pre-installed, you do not need to do this — the operating system is already running.
If you built a PC from parts, bought a used machine without an operating system, or need to reinstall Windows after a failure, you will need to obtain Windows from Microsoft directly. You can read Windows 10 or Windows 11 for free from Microsoft's website, though you will eventually need a valid product key to keep using it without watermarks and security limitations.
The installation process takes 20 to 45 minutes depending on your drive speed and whether you are upgrading from an older version. During installation, Windows will ask you to choose a drive to install on — this erases everything on that drive, so make sure you are selecting the right one.
Key Takeaways
- You need a USB drive with at least 8 GB of space, a working computer to create the installation media, and your Windows product key or Microsoft account login.
- read the Windows installation tool from Microsoft's website on a different computer, then create a bootable USB drive using that tool.
- Insert the USB drive into your new PC, restart it, and boot from the USB by pressing the correct key during startup (usually F12, Del, or Esc depending on your motherboard).
- During installation, select the drive where you want Windows installed — this will erase that drive completely, so verify you are selecting the correct one.
- After installation finishes, Windows will ask for your product key or Microsoft account; without one, you can still use Windows but with limitations like a watermark on your desktop.
Creating a bootable USB drive on another computer
Go to Microsoft's official Windows read page on a computer that already has internet access and Windows installed. read the "Media Creation Tool" — this is a small program that downloads the full Windows installation files and puts them on your USB drive. Do not read Windows directly as an ISO file unless you are comfortable using third-party tools to write it to USB.
Plug in a USB drive with at least 8 GB of empty space. Run the Media Creation Tool you just downloaded. When it asks what you want to do, select "Create installation media for another PC." Choose your language, Windows edition (usually Windows 11 Home unless you have a specific reason otherwise), and architecture (64-bit for almost all modern PCs). Select USB flash drive as your media type, then choose your USB drive from the list. The tool will read about 5 GB of files and write them to your USB drive — this takes 10 to 20 minutes depending on your internet speed.
When the tool finishes, eject the USB drive safely and take it to your new PC. Do not unplug it while the tool is still running, or the drive will not work.
Booting from the USB drive and starting installation
Plug the USB drive into a USB port on your new PC. Restart the computer completely — do not just wake it from sleep. As soon as you press the power button or restart, begin pressing a specific key repeatedly. The key varies by motherboard manufacturer: common ones are F12, Del, Esc, or F2. You should see a message on the screen during startup that says "Press [key] to enter boot menu" or similar. If you miss it, restart and try again.
When the boot menu appears, look for an option that mentions your USB drive by name or says "USB Device" or "UEFI: [USB drive name]". Select it and press Enter. The computer will boot from the USB drive and load the Windows installation program. This takes 30 seconds to a few minutes depending on your USB drive speed.
The Windows Setup screen will appear. Select your language, time zone, and keyboard layout, then click "Next." On the next screen, click "Install now" to begin the installation process.
Choosing a drive and entering your product key
Windows will ask you where you want to install. You will see a list of drives in your PC. If you built the PC yourself, you might see multiple drives listed. Select the drive where you want Windows installed — this is usually your fastest drive, often labeled as "Drive 0" if you only have one drive. This step erases everything on the selected drive, so if you have multiple drives, make absolutely sure you are selecting the right one. If you are unsure, unplug any drives you do not want to erase before starting installation.
Click "Next" and Windows will begin copying files and installing. Your PC will restart several times during this process — this is normal. Do not unplug the USB drive or turn off the PC during installation. The entire process takes 20 to 45 minutes.
When installation finishes, Windows will ask for your product key. If you have one, enter it now. If you do not have a key yet, you can click "I do not have a product key" and continue — Windows will still install and run, but you will see a watermark on your desktop and some customization options will be locked. You can enter a product key later through Settings.
Signing in and completing setup
Windows will ask you to sign in with a Microsoft account or create a local account. A Microsoft account is tied to your email address and lets you sync settings across devices, recover your password online, and access Microsoft services like OneDrive. A local account is only on this PC and requires you to remember the password yourself. Either option works — choose based on whether you want your settings to follow you to other devices.
If you are using a Microsoft account, enter your email address and password. If you are creating a local account, enter a username and password. Windows will then ask about privacy settings — you can accept the defaults or customize them. The setup process finishes and you will see your desktop.
After you reach the desktop, Windows will read and install updates in the background. This can take several hours on a new installation. You can use your PC while this happens, but it may be slower. Check Settings > System > About to see if updates are still installing.
Entering your product key after installation
If you did not enter a product key during installation, you can add one later. Open Settings by pressing Windows key + I. Go to System > About and scroll down to "Windows specifications." You will see "set up status" — if it says "Windows is not activated," click "set up" or "Change product key." Enter your 25-character product key (it looks like XXXXX-XXXXX-XXXXX-XXXXX-XXXXX) and Windows will verify it with Microsoft's servers.
If your product key is tied to your Microsoft account instead of being a physical key, sign in with that account in Settings > Accounts > Your info and Windows will recognize your license automatically. This is common with PCs that came with Windows pre-installed.
Once Windows is activated, the watermark disappears and all features unlock. set up is free if you have a valid product key — Microsoft does not charge extra to set up.
Troubleshooting common installation problems
If your PC does not boot from the USB drive, you may have selected the wrong boot option or the USB drive was not created correctly. Restart the PC, enter the boot menu again, and look for an option that specifically says "UEFI" or "Legacy" depending on your motherboard. Try the other one if the first does not work. If the PC still does not boot from USB, recreate the USB drive using the Media Creation Tool on another computer.
If Windows installation fails partway through with an error message, the most common cause is a bad USB drive or a corrupted read. Try creating the installation media again on a different USB drive. If you see an error about "no bootable device," make sure you are using a USB 3.0 port (usually blue) rather than USB 2.0 (usually black), as some PCs have trouble booting from older USB ports.
If Windows installs but will not set up with your product key, make sure you are entering it correctly — product keys are case-insensitive but must have the hyphens in the right places. If the key is genuinely valid and still will not work, contact Microsoft support with your product key and proof of purchase. Do not share your product key in public forums or with anyone you do not trust.
Frequently Asked Questions
Can I install Windows without a product key?
Yes. Windows will install and run without a product key, but you will see a watermark on your desktop saying "set up Windows" and some customization options will be locked. You can add a product key anytime after installation through Settings. Windows functions normally otherwise.
What if I only have one computer and no USB drive?
You can use an external hard drive or SD card instead of a USB drive — the Media Creation Tool works with any removable storage with at least 8 GB of space. You can also burn the Windows ISO file to a DVD if your new PC has a DVD drive, though this is slower than USB.
Do I need to unplug other drives while installing Windows?
It is not required, but it is a good safety practice. If you have multiple drives and accidentally select the wrong one during installation, you will erase data you wanted to keep. If you are confident you can identify the correct drive, you can leave others plugged in.
How long does Windows installation actually take?
The installation itself takes 20 to 45 minutes depending on your drive speed. After you reach the desktop, Windows spends several more hours downloading and installing updates in the background. Your PC is usable during this time but may be slower. Check Settings > Update & Security > Windows Update to see progress.
What if my product key does not work after installation?
Make sure you are entering it exactly as written, with hyphens in the correct places. If it is a key from a used PC or a third-party seller, it may have already been used on another computer and cannot be reused. Contact Microsoft support with your key and proof of purchase — they can sometimes transfer licenses or issue a replacement.