You will need a unique product key to reinstall Windows on your PC. This is more confusing than it sounds – you may not be able to re-use the key your computer’s manufacturer used.
Reinstalling Windows often feels necessary, especially on new PCs that come packed with bloat ware. You can legally download Windows 7, 8, and 8.1 installation media directly from Microsoft.
Where Is The Windows Product Key Located?
Three Places You Might Find the Key:
- Stored in software on your PC: When you (or your PC manufacturer) installs Windows, Windows stores its product key in the registry. You can extract this product key, and — often — enter it when reinstalling Windows on your PC. Crucially, you’ll need to grab it from your operating system before you begin reinstalling Windows or it could be deleted if you format your hard drive.
- Printed on a sticker: Some PCs use a technology called “System Locked Pre-installation,” or SLP. If your PC uses this, the product key on your PC — the one stored in the registry, and the one key-viewer applications display — will be different from the actual key your PC needs. The actual key is on a certificate of authenticity (COA) sticker on your PC or its power supply. The one in the registry and key-viewer application is a red herring. This system was common for Windows 7 PCs.
- Embedded in your PC’s UEFI firmware: Many newer PCs that come with Windows 8 use a new method. The key for the version of Windows the PC comes with, is stored in the computer’s UEFI firmware or BIOS. You don’t even need to know it — assuming you’re installing the same edition of Windows the PC came with, it should automatically activate and work without you needing to enter a key. It’ll all happen automatically.
Be sure to use the same version and edition of Windows the computer came with. In other words, if it came with Windows 7 Home Premium, you can’t install Windows 7 Professional.
Where Is The Windows Product Key Stored?
The product key is stored in the registry on your computer, and it can be read by simple key-viewing programs or even basic scripts. We recommend NirSoft ProduKey for this. Despite all our railing against the Windows freeware ecosystem, NirSoft’s software has always been excellent and never tried to force junk onto your PC. Be sure to download it from NirSoft’s official website and not a third-party download site, though.
Download ProduKey, run it, and look at the Windows product key it displays. Be sure to read the “Product Key” column, and not the “Product ID” column. Write this product key down, print it out, or store it somewhere electronically. You’ll need it when reinstalling Windows, and you may not be able to get it again if you wipe your hard drive.
But, beware — this product key may not actually work for reinstalling Windows on your PC.
Read the Key From the COA Sticker
So, is that product key usable for reinstalling Windows on your PC? If you have a Windows 7-era PC, there’s a good chance the PC’s key is a single key the manufacturer uses for all their PCs. Thanks to “System Locked Pre-installation,” you’re not allowed to use that key to install Windows. If you try, you’ll get error messages about the key being invalid.
To check, you’ll need to look for a certificate of authenticity sticker on your computer. The COA sticker verifies that the computer came with an authentic copy of Windows, and that sticker has a product key printed on it. You’ll need that product key to reinstall Windows — and, if the manufacturer used System Locked Pre-installation, that key is different form the one your PC came with in software.
Examine your computer to find the key. On a laptop, it may be on the bottom of the laptop. If your laptop has a removable battery, it may be under the battery. If there’s some sort of compartment you can open, it might be in there. It may even be stuck to the laptop’s charger brick. If it’s a desktop, look on the side of the desktop’s case. If it’s not there, check the top, back, bottom, and anywhere else it might be.
If the key has rubbed off of the sticker, there’s not much you can do. You can try contacting your computer’s manufacturer and explaining what happened, but we can’t guarantee they’ll help. Microsoft would always be happy to sell you another key, though!
Is the Key Stored in Hardware?
Newer Windows 8 PCs can avoid all these problems. The key isn’t stored on software where it can be wiped, or on a sticker where it could be smudged off or removed. No one can glance at your computer’s COA sticker to steal its product key. Instead, the key is stored in the computer’s UEFI firmware or BIOS by the manufacturer.
You don’t have to do anything special if you have this. If your computer came with Windows 8 and it doesn’t have a COA sticker, don’t worry. You should just be able to reinstall the same edition of Windows the PC came with and it should just work without even asking you for a key. (Still, it may be best to run NirSoft’s ProduKey and write down any key you find there before reinstalling Windows — just in case.)
The product key system is complicated to understand because Microsoft doesn’t really want typical Windows users to reinstall Windows on their PCs. Instead, they’d rather you use your computer manufacturer’s recovery media. But the recovery media is full of the bloat ware you don’t want on your PC — that’s why so many geeks often opt to reinstall Windows on their new PCs.
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