How to Activate Windows 10 and Windows 11 with a Product Key

A Windows product key is 25 characters long, written in five groups of five: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. Activation takes about a minute. The steps are the same for Windows 10 and Windows 11, Home and Pro — only the path through Settings differs, and both are given below. Windows 7 and Windows 8.1 are covered at the end.

In short

• Copy the key rather than retyping it — the letters O and I never appear in it, those are zeros and ones.
• Open Settings → System → Activation (Windows 10: Update & Security → Activation) and expand Change product key.
• Paste the key and click Activate. If it will not go through, you can use the Microsoft Activation Portal instead.

Before you start

• Check which edition is installed. Open Settings → System → About and look at "Edition". A key is tied to one edition: a Pro key will not activate a Home installation — but it will upgrade it, which is covered below. A Windows 10 key will not activate Windows 11, and the reverse is also true.
• Be connected to the internet. Online activation contacts Microsoft's activation servers directly.
• Copy the key rather than retyping it. Most rejected keys are typing mistakes. The letters O and I never appear in Microsoft keys — if you see them, they are the digits 0 and 1.

If Windows is not installed yet

A product key does not download Windows — it unlocks an installation that is already on the PC. Microsoft publishes the installation media itself, free of charge:

• Windows 11 — download from Microsoft
• Windows 10 — download from Microsoft

Each page offers the Media Creation Tool, which writes a bootable USB stick, and a plain ISO file for those who prefer one. Install Windows first and skip the key when the installer asks for it — Windows runs perfectly well unactivated while you get to that. Then activate with the steps below.

Method 1: activate through Settings

• Open Settings (Windows key + I).
• On Windows 11, go to System → Activation. On Windows 10, go to Update & Security → Activation.
• Expand Change product key and click Change.
• Paste your 25-character key and click Next.
• Click Activate and wait for the confirmation.

If your PC currently runs a Home edition and you enter a Pro key here, Windows offers to upgrade the edition instead. Accept it — the upgrade keeps your files and installed programs, and the PC restarts once when it finishes.

Method 2: activate from the command line

This is the faster route if Settings refuses to open the activation panel, and it gives you a clearer error message when something is wrong. It works the same on Windows 10 and Windows 11.

• Right-click Start and choose Terminal (Admin) or Command Prompt (Admin).
• Install the key: slmgr /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
• Activate it: slmgr /ato

Each command opens a small dialog box with the result. If activation fails, that box shows an error code — write it down, it tells you exactly what went wrong.

Windows 7 and Windows 8.1

Both use the same 25-character key and the same slmgr commands as Method 2. Only the click-through route differs, because neither version has the Settings app that Windows 10 and 11 use.

• Windows 7: open Start → Control Panel → System and Security → System. The activation section sits at the bottom of that page — click Change product key, paste the key and confirm.
• Windows 8.1: press Windows key + X and choose System, or open Control Panel → System. Change product key is at the bottom of the same page.
• Either version, command line: open Start, type cmd, right-click Command Prompt and choose Run as administrator. Then slmgr /ipk followed by slmgr /ato, exactly as above.

If online activation does not complete on these versions, the key can still be activated by telephone — the process is in our phone activation guide.

Confirm that activation worked

Go back to the activation screen — System → Activation on Windows 11, Update & Security → Activation on Windows 10. The status should read Active. For the full licence details, run slmgr /xpr in a command prompt — it states whether the machine is permanently activated.

If the key is rejected

Work through these in order:

• Wrong edition or wrong version. A Pro key on a Home installation, or a Windows 10 key on Windows 11, produces an immediate rejection. Check Settings → System → About.
• A character was mistyped. Paste the key rather than typing it.
• No internet connection. Activation needs to reach Microsoft's servers; a captive-portal Wi-Fi network or a strict corporate firewall can block it.
• An error code appeared. Look it up in our guide to Windows activation error codes — each one has a specific cause.

Activating Windows Server instead? It has one extra step that catches most people — see our Windows Server activation guide.

Still stuck? Send us your order number and the exact error code through our support form, and we will sort it out.

Last checked: September 2026