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On Windows, open PowerShell or Windows Terminal and run (Get-CimInstance -ClassName Win32_BIOS -Property SerialNumber).SerialNumber. On a Mac, choose Apple menu > About This Mac. If the computer will not start, check its label—usually on the bottom, side, or back—or its original packaging. The instructions below cover Linux and Chromebooks too, and explain what to do if the number is blank or doesn’t match the label.
First, make sure you have the right number
A computer serial number is an identifier assigned to the complete computer by its manufacturer. It may be printed on the chassis and stored in firmware, where the operating system can read it. Manufacturers use it for support, warranty checks, registration, and service records—but similar-looking numbers can identify something else.
- Serial number: Identifies a computer as a unit.
- Service Tag: Dell’s term for its system identifier. You may see it called a Service Tag or serial number in support contexts.
- Product number or product ID: Often identifies a product family or configuration. HP may request a product number as well as the serial number.
- Model number: Identifies a model or series, not usually one specific computer.
- Asset tag: An identifier assigned by a business, school, or other organization for inventory.
- BIOS serial number: The system serial exposed through firmware; it can be missing or generic.
- Drive serial number: Identifies an SSD or hard drive, not the whole computer.
A Windows product ID or activation key is not the computer’s hardware serial number. If support asks for a serial number, check the label or the system-serial methods below rather than sending a Windows license identifier.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsCheck the computer’s label first
Look for Serial Number, S/N, SN, System Serial Number, or, on a Dell, Service Tag. Common locations include:
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- Laptop: The bottom cover. On some older laptops, the label is inside or beneath a removable battery.
- Desktop tower: The rear, side, or top panel.
- All-in-one: The side or back of the display enclosure.
- Packaging and paperwork: The original box, invoice, receipt, shipping documents, or service paperwork may list it.
Placement varies by manufacturer and model. For example, Lenovo documents labels on product sides or backs, and some ThinkPads have a label on the bottom or under the battery (Lenovo’s serial-number guide). Use a flashlight and photograph the label so you can enlarge it; check easily confused characters such as 0/O, 1/I, 5/S, and 8/B. Don’t mistake a barcode number, model number, regulatory marking, or Windows license sticker for the serial.
A serial number can help someone identify your device, so don’t post it publicly or share a photo that also reveals a receipt, address, or account details. Send it through an official support channel when needed.
Find a serial number in Windows
PowerShell: the recommended method
- Open Start and search for PowerShell, or open Windows Terminal.
- Run this command:
(Get-CimInstance -ClassName Win32_BIOS -Property SerialNumber).SerialNumber- Copy the value shown and enter it exactly where needed.
This queries the SerialNumber property of the Win32_BIOS class. Microsoft documents both the class and PowerShell’s Get-CimInstance approach for querying computer information (Win32_BIOS reference; PowerShell WMI/CIM guidance). The command reads what the computer’s firmware reports; it cannot supply a genuine manufacturer serial if firmware has no usable value.
These equivalent forms can be useful if you prefer their output format:
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Get-CimInstance -ClassName Win32_BIOS | Select-Object -ExpandProperty SerialNumber(Get-CimInstance Win32_BIOS).SerialNumberSystem Information: a graphical option
- Press Windows + R.
- Type
msinfo32and press Enter. - In System Summary, look for System Serial Number, if the manufacturer supplied it.
Microsoft’s System Information documentation describes Msinfo32.exe as a built-in tool for viewing hardware and system details. Running it as an administrator may show more complete information, but a serial field is not guaranteed to be populated.
Command Prompt and WMIC: legacy fallback
Older guides often recommend this Command Prompt command:
wmic bios get serialnumberIt may still work on some systems, but WMIC—the command-line utility, not WMI itself—is deprecated. Its availability varies across Windows versions and configurations. Prefer the PowerShell command above; if Windows says wmic is not recognized, you do not need to install an unofficial replacement. See Microsoft’s WMIC documentation.
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BIOS or UEFI setup
If Windows cannot start, enter the computer’s BIOS/UEFI setup and look for system information. The key or startup procedure and the menu location vary by manufacturer and model; consult the computer maker’s instructions. Firmware may show the same serial as the operating system—or may show a blank or generic value.
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Find a serial number on a Mac
If macOS starts
- Open the Apple menu.
- Select About This Mac.
- Find the Serial Number entry.
You can also open System Information from About This Mac (the button or wording varies by macOS version) and check the hardware overview. Apple’s serial-number guide covers these options and other ways to identify a Mac.
If the Mac won’t start normally
Check the exterior and original packaging or purchase documentation. A Mac laptop may have a serial on its underside; some desktop Macs or displays have one on the back. Labels can be hard to read or absent, so they are not guaranteed to be available on every model.
Apple also documents finding the number in macOS Recovery and opening Terminal from Recovery’s Utilities menu. Startup and Recovery procedures differ between Intel-based Macs and Apple silicon, so follow Apple’s model-specific instructions rather than assuming one key combination works for all Macs.
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Find a serial number in Linux
On many Linux systems, dmidecode reads firmware’s SMBIOS information. Run:
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sudo dmidecode -s system-serial-numberOr inspect the system record:
sudo dmidecode -t system | grep -i serialsudo is normally needed, and dmidecode may not be installed by default. Another firmware-backed option is:
sudo cat /sys/class/dmi/id/product_serialThese commands report only the data firmware provides. A blank result or a value such as To be filled by O.E.M., Default string, or None means the field is not useful—not that Linux has discovered a hidden serial. Lenovo documents system and baseboard queries in its serial-number guidance.
If you specifically need the motherboard or baseboard serial, use a baseboard query:
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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →sudo dmidecode -s baseboard-serial-numberThat identifies a component, not necessarily the complete computer. A custom-built desktop may have a motherboard serial but no manufacturer-assigned serial for the assembled PC.
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Find a Chromebook serial number
At the Chromebook sign-in screen, press Alt + V. The serial number should appear near the top-right. This is useful when you cannot sign in. You can also check the physical label or the manufacturer’s support information; exact settings and support paths can vary by device. Lenovo includes the Alt + V method in its device identification guidance.
Manufacturer tools and support pages
- Lenovo: Lenovo Vantage can display a Lenovo PC’s serial number, and supported systems may show it in BIOS/UEFI. If Vantage is not installed, check Lenovo’s guidance or use the label. Its warranty lookup accepts a serial number.
- HP: HP Support Assistant can help identify a computer. HP’s warranty checker may require both the serial number and product number, depending on the device and region; see HP’s identification and warranty guidance.
- Dell: Look for the Service Tag, Dell’s system identifier, on the device or in system information. Use Dell’s official support channel for a lookup; don’t assume that another manufacturer’s “product number” terminology means the same thing.
- Apple: Use About This Mac, System Information, the device label if present, or Apple’s official instructions.
If the serial number is missing, generic, or incorrect
- PowerShell or Linux returns a blank or generic value: Check the chassis label, BIOS/UEFI, original box or invoice, and the manufacturer’s support utility. Firmware may never have been populated correctly.
- The label is damaged or unreadable: Photograph and enlarge it, then compare with the OS result, firmware screen, paperwork, or OEM tool. Contact the manufacturer with the model and proof of purchase if you still cannot identify it.
- The numbers disagree after a repair: A motherboard replacement can change the firmware-reported identifier while the chassis label remains unchanged. Give support both values and explain the repair rather than silently choosing one.
- It is a custom-built PC: There may be no whole-system serial. A motherboard or case identifier is not automatically the serial number for the assembled computer.
- It is a virtual machine: The guest may report a generated, template-derived, or meaningless serial. For inventory, use the hypervisor or cloud provider’s instance identifier as well.
- It is managed by work or school: Ask IT to check the organization’s asset record. Don’t bypass device-management controls or post the identifier publicly.
What a serial number can—and can’t—do
A serial number is useful when requesting warranty service or technical support, registering a device, documenting an insurance claim, making a police report, or managing an inventory. Check it against the label before submitting it, and use the manufacturer’s official support or warranty page. Some services ask for an additional model or product number.
A serial number identifies a device; it does not by itself show where a lost or stolen computer is. Location features depend on previously enabled account or device-tracking services, not on entering the serial number into a lookup site.
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If you need the serial number of an SSD or hard drive, use a storage-device method instead: the drive has its own identifier, which is different from the computer’s serial number.
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