Where to find your computer's serial number

Your computer's serial number is a unique identifier printed or encoded by the manufacturer. You need it when you contact tech support, file a warranty claim, or track a device you own. The location depends on your operating system — Windows, Mac, and Linux each store this information differently, and it takes about two minutes to find.

The serial number is not the same as your product key or device name. It's a manufacturer-assigned code that proves you own that specific machine. Most computers have it in multiple places: physically on a sticker under the laptop or on the tower case, and also stored in the system files where you can retrieve it without opening anything.

Key Takeaways

  • Windows computers store the serial number in System Information, which you can open by typing "msinfo32" into the Run dialog.
  • Mac computers display the serial number in System Report, found under the Apple menu under About This Mac.
  • Linux systems require a command-line tool like dmidecode or lshal, depending on your distribution.
  • The physical serial number on a sticker or case label is the most reliable backup if the system files are corrupted.
  • Different manufacturers use different label formats, so the serial number may be labeled as "Serial Number," "S/N," or "Service Tag."

Finding the serial number in Windows

The fastest way in Windows is through System Information. Press the Windows key and R together to open the Run dialog, type msinfo32, and press Enter. A window will open showing your system details. Look for the line labeled System Serial Number — this is your computer's unique identifier.

If the Run dialog does not work, you can reach System Information another way. Click the Start button, type "System Information" into the search box, and click the result. The serial number appears in the main panel on the right side of the window, usually near the top.

Some manufacturers like Dell use a different label. If you see Service Tag instead of System Serial Number, that is your serial number. HP and Lenovo may label it differently as well, but it will always be a unique string of letters and numbers specific to your machine.

Finding the serial number on a Mac

On a Mac, click the Apple menu in the top-left corner and select About This Mac. A window will open showing your Mac's specifications. Look for Serial Number in the list — it appears near the top, usually below the Mac model name.

If you are using an older Mac or need more detailed information, click the System Report button in that same window. This opens a more detailed view where the serial number is listed under Hardware Overview.

The serial number on a Mac is always visible in these menus and does not require any special permissions or command-line tools. Write it down or take a screenshot if you need to reference it later.

Finding the serial number in Linux

Linux does not have a single standard location for the serial number because Linux runs on many different hardware types. The method depends on your distribution and hardware manufacturer. The most common approach is to use the dmidecode command, which reads the system's BIOS data.

Open a terminal and type sudo dmidecode -s system-serial-number, then press Enter. You will be asked for your password. After you enter it, the serial number will appear on the next line. If dmidecode is not installed on your system, you can install it using your distribution's package manager — on Ubuntu or Debian, type sudo apt install dmidecode.

If dmidecode does not work or is not available, try lshal or check the manufacturer's documentation for your specific hardware. Some systems also display the serial number in the BIOS, which you can access by restarting your computer and pressing a key like F2, F10, or Delete during startup (the exact key varies by manufacturer).

Checking the physical serial number label

Every computer has a physical serial number printed on a label somewhere on the case. On a laptop, this is usually on the bottom or back. On a desktop tower, check the back panel or the side. The label will show the manufacturer name, model number, and serial number.

The physical label is the most reliable source if your system files are corrupted or if you cannot access the operating system. Take a photo of the label or write down the serial number exactly as it appears — include all letters, numbers, and hyphens. Manufacturers sometimes use different formats, so copy it character for character.

If the label is worn or illegible, the system information method is your next best option. If both the label and the system files are inaccessible, contact the manufacturer's support team with your proof of purchase, and they can help you locate the serial number another way.

What to do with your serial number once you have it

Write down your serial number and store it somewhere safe — a document on your computer, a password manager, or a physical notebook. You will need it if you contact technical support, file a warranty claim, or report the computer stolen or lost.

When you contact support, have the serial number ready before you call or chat. Support agents use it to pull up your device's history, warranty status, and any previous issues. This speeds up the process and ensures they are helping with the right machine if you own multiple devices.

If you are selling or giving away the computer, the new owner may need the serial number for their own records or warranty purposes. Include it in the documentation you hand over.

Frequently Asked Questions

Is the serial number the same as the product key?

No. The serial number identifies the physical device itself. The product key is a code that proves you own a license to use the software (like Windows or Office) on that device. You need both for warranty and support purposes, but they are different things.

What if System Information shows a blank field where the serial number should be?

This usually means the manufacturer did not store the serial number in the system files, or the BIOS has been reset. Check the physical label on the case instead. If the label is also missing or illegible, contact the manufacturer with your proof of purchase and they can help you identify the device.

Can I change my computer's serial number?

The physical serial number cannot be changed — it is part of the hardware. The system-stored serial number can be modified by editing BIOS settings, but doing so is not recommended and may void your warranty or cause support issues. Leave it as the manufacturer set it.

Do I need the serial number to reinstall Windows or Mac?

You do not need the serial number to reinstall the operating system. You need the product key for Windows or your Apple ID for Mac. The serial number is useful for warranty and support, but not for installation or activation.

Where is the serial number if I built my own computer?

A custom-built computer does not have a single manufacturer serial number. Each component (motherboard, graphics card, storage drive) has its own serial number. If you need to identify the machine as a whole, use the motherboard's serial number, which you can find in System Information or on the motherboard itself.