How to find your computer's serial number

Your computer's serial number is a unique identifier printed or encoded by the manufacturer. It appears in different places depending on whether you have a Windows PC, Mac, or Linux machine. The fastest way to find it is through your system settings—no tools or software needed. You can also find it physically on the device itself, on the original box, or in your purchase receipt.

The serial number matters when you contact manufacturer support, file a warranty claim, track a stolen device, or sell your computer. It proves you own the machine and helps technicians pull up your specific hardware configuration and service history.

Key Takeaways

  • Windows computers show the serial number in System Information (search "msinfo32" in the Start menu) under the System Summary tab.
  • Mac computers display the serial number in About This Mac, found by clicking the Apple menu and selecting System Settings or About This Mac.
  • The serial number is also printed on a sticker on the back or bottom of most laptops and desktops, or on the original box.
  • Write down or photograph your serial number and store it somewhere safe—you will need it for warranty claims or if your computer is lost or stolen.

Finding the serial number on Windows

Open the Start menu and type msinfo32 into the search box, then press Enter. The System Information window will open. Look for the field labeled System Serial Number in the System Summary tab—it should appear near the top of the list, often just below the computer name and manufacturer.

If that field is blank, try the alternative method: right-click on "This PC" or "My Computer" on your desktop, select Properties, and scroll down to look for a serial number field. Some manufacturers also include it in their own system utility software, which you can find in the Control Panel under Programs.

Write down the exact number as it appears—serial numbers are case-sensitive and often include both letters and numbers. Take a screenshot or photograph it so you have a backup copy.

Finding the serial number on a Mac

Click the Apple menu in the top-left corner of your screen and select About This Mac. A window will appear showing your Mac's hardware details. Look for the field labeled Serial Number—it is usually displayed near the top, alongside the model name and processor information.

On newer Macs running macOS Monterey or later, you may need to click System Settings instead of About This Mac. The serial number will still appear in the same location. Copy the number and save it in a safe place, such as a notes app or document on your computer.

Locating the physical serial number sticker

Most computers have a sticker with the serial number printed on the back, bottom, or side of the device. For laptops, check the underside of the machine—you may need to flip it over or remove the battery to see the sticker clearly. For desktop computers, look on the back panel or the side of the tower.

The sticker usually includes the manufacturer's logo, the model number, and a barcode alongside the serial number. The serial number itself is often labeled as "S/N" or "Serial No." and consists of 8 to 20 characters. If the sticker is worn or faded, the system settings method is more reliable.

Checking your original purchase documents

Your computer's serial number may also appear on the original box, the receipt, or the invoice from the retailer or manufacturer. Check the outside of the box first—manufacturers often print key information there for quick reference. If you still have the receipt, look for a serial number field near the product details.

If you purchased the computer online, log into your account with the retailer or manufacturer and view your order history. Many companies display the serial number in the order details or in a downloadable invoice. This is especially useful if you no longer have the physical box or receipt.

What to do once you have the serial number

Once you have located and recorded your serial number, store it in at least two places. Keep a written copy in a safe location such as a drawer or filing cabinet, and save a digital copy in a password-protected document or notes app. Some people photograph the sticker on the back of their computer as a backup.

If your computer is lost, stolen, or needs warranty service, you will have the serial number ready without having to search for it. You can also register your device with the manufacturer's website using the serial number, which may unlock additional support options or warranty coverage.

Frequently Asked Questions

What if the serial number field is blank in System Information?

Some computers, especially custom-built PCs or older machines, may not have a serial number stored in the system settings. In this case, check the physical sticker on the back or bottom of the device, or contact the manufacturer with your model number. They can often look up the serial number using other identifying information.

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

No. The serial number identifies the physical hardware itself, while a product key or license key is tied to software like Windows or Microsoft Office. You will find the product key in System Information under a different field, or in the original software packaging.

Can I look up a computer's history using the serial number?

The manufacturer can use the serial number to pull up warranty information, service records, and the original purchase date. However, they cannot access personal files or data on the computer. If you are buying a used computer, ask the seller for the serial number and contact the manufacturer to verify the warranty status.

What should I do if I lost my computer and have the serial number?

Report the loss to your local police department and provide them with the serial number. You can also contact the manufacturer and ask them to flag the serial number in case someone tries to register it or seek service. This does not recover the device, but it creates a record of the loss.