A Windows product key is a 25-character code used to activate Windows. It looks like this:
PRODUCT KEY: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
If you’re reinstalling Windows 10, you might not need a Windows product key. See Activation in Windows 10 for more info.
If you're reinstalling Windows 10 due to a motherboard problem or some other hardware issue, see Reactivating Windows 10 after a hardware change.
For more Windows 10 download info, see Download Windows 10.
Where to find your product key depends on how you got your copy of Windows:
- From an authorized retailer. The product key is on a label or card inside the box that Windows came in.
- A new PC running Windows. The product key is preinstalled on your PC, included with the packaging the PC came in, or included on the Certificate of Authenticity (COA) attached to the PC.
- A digital copy from a Microsoft website. The product key is in the confirmation email you received after buying it. Or, it may be distributed as a digital license if you bought Windows 10, in which case it doesn't include a product key. Learn more about activation in Windows 10.
- Free upgrade to Windows 10. If you upgraded to Windows 10 for free from Windows 7 or Windows 8.1, you should have a digital license instead of a product key. For more info about digital licenses in Windows 10, see Activation in Windows 10.