Where to find your serial number in Windows

Your PC's serial number is a unique identifier assigned by the manufacturer. You can find it in three places without opening your computer: the System Information window, the command line, or a physical label on your machine.

The fastest method is to open System Information. Press the Windows key and type "System Information," then click the app. Look for the field labeled System Serial Number — this is what you need. If that field is blank, your manufacturer may have stored it under a different name like "Serial Number," "Service Tag," or "Product ID." Write down exactly what you see.

If System Information shows nothing, try the command line. Press Windows key + R, type cmd, and press Enter. In the black window that opens, type this line exactly: wmic bios get serialnumber and press Enter. The serial number will appear on the next line. Copy it carefully — these strings often mix letters and numbers that look similar, like the letter O and the number 0.

Key Takeaways

  • Open System Information by pressing Windows key and typing "System Information," then look for the System Serial Number field.
  • If System Information is blank, use the command line by typing wmic bios get serialnumber to retrieve it from your BIOS.
  • Check the physical label on the back or bottom of your PC case — manufacturers often print the serial number there as well.
  • Different manufacturers use different field names, so look for "Service Tag," "Product ID," or "Serial Number" if the exact label varies.
  • Write down the serial number exactly as it appears, including all letters and numbers, because manufacturers use it to verify warranty and ownership.

Checking the physical label on your PC

Before you dig into software, check the outside of your machine first. Most desktop PCs have a label on the back panel or bottom of the case. Laptops usually have the serial number on the bottom, under the battery, or on the inside of the access panel. Look for a sticker with small text — the serial number is often printed there alongside the model number and other codes.

Write down what the label says, but understand that this number may not match what appears in Windows. Some manufacturers print the chassis serial number on the case but store a different system serial number in the BIOS (the firmware that runs before Windows loads). Both are legitimate identifiers, but support teams usually want the one from System Information or the command line, because that is what the operating system recognizes.

Using PowerShell if the command line does not work

If the wmic command returns nothing or an error, try PowerShell instead. Right-click the Start button and select "Windows PowerShell (Admin)" or "Terminal (Admin)." In the window that opens, type this line: Get-WmiObject -Class Win32_BIOS | Select-Object SerialNumber and press Enter.

PowerShell will display the serial number on the next line. This method pulls the same information from your BIOS as the command line does, but sometimes works when the other method fails. If both return nothing, your BIOS may not have a serial number stored — this is rare but happens on some older or custom-built machines.

What to do if you cannot find a serial number

If System Information, the command line, and the physical label all show nothing or different numbers, your PC may be custom-built or very old. In that case, the manufacturer's serial number may not exist. You can still identify your machine using the Product ID or Device ID instead, which Windows generates automatically.

To find your Product ID, open System Information and look for the field labeled "System SKU" or "Product ID." This is a unique code that Windows creates based on your hardware. It is not the same as a manufacturer serial number, but support teams can use it to look up your machine if you explain that you do not have a traditional serial number. If you are trying to register a warranty or contact support, tell them what you found — they will let you know if it is the right identifier.

Why manufacturers hide the serial number in different places

Different PC makers store the serial number in different locations because there is no single standard. Dell calls it a "Service Tag," HP calls it a "Serial Number," and Lenovo may label it a "Machine Type" or "Serial Number" depending on the model year. Some manufacturers print it on the case but do not store it in Windows at all.

This is why checking all three places — System Information, the command line, and the physical label — gives you the best chance of finding what you need. When you contact support or register a warranty, tell them where you found the number and what label it had. Support staff are used to this confusion and will know whether you have given them the right code.

Saving your serial number for future use

Once you have found your serial number, store it somewhere you can find it later. Take a photo of the System Information window or the physical label and save it to your phone or cloud storage. Write it down in a notebook or password manager. You will need this number if your hard drive fails and you need to prove ownership, if you contact manufacturer support, or if you sell the PC and need to transfer the warranty.

Many people also create a text file on their desktop called "PC Info" and paste their serial number, model number, and purchase date there. This takes 30 seconds and saves you from having to hunt for it again when you are in the middle of a support call or warranty claim.

Frequently Asked Questions

Is the serial number the same as the product key or license key?

No. The serial number identifies your physical machine. The product key (or license key) identifies your copy of Windows. You can find your Windows product key by typing wmic os get serialnumber in the command line, but that is a different number than your PC's serial number. Support will ask for one or the other depending on what they are helping you with.

Can I change my PC's serial number?

You can change what appears in System Information using specialized tools, but this is not recommended. Changing your serial number can break warranty claims, confuse support staff, and may violate your manufacturer's terms. If you believe your serial number is wrong, contact the manufacturer instead of trying to fix it yourself.

What if two PCs have the same serial number?

This should not happen with legitimate machines from major manufacturers. If you have two PCs with identical serial numbers, one of them may be a counterfeit, refurbished without a new number, or have corrupted BIOS data. Contact the manufacturer with both serial numbers and your proof of purchase — they can investigate and issue a new number if needed.

Do I need the serial number to reinstall Windows?

No. You can reinstall Windows without the serial number. You will need your Windows product key (which is different from your PC serial number), but Windows will let you reinstall and set up using that key alone. The PC serial number is mainly for warranty, support, and ownership verification.

Where do I find the serial number on a custom-built PC?

Custom-built PCs do not have a manufacturer serial number because no single company made the whole machine. You can use your Windows Product ID or Device ID instead. If you need to prove ownership for support purposes, keep your receipts for the parts and your Windows license key — those serve as proof instead of a serial number.