How to Find Your Laptop's Serial Number (and Check a Used One Before You Buy)

A laptop's serial number is the one detail that ties that exact machine to you. Police ask for it when you report a theft, insurers ask for it when you claim, and manufacturers ask for it before they'll touch a warranty repair. It is also the quickest way to find out whether a second-hand laptop has a history its seller isn't mentioning.

The good news is that every laptop has one, and there are at least three places to find it. The better news is that you only need to find it once: write it down, photograph the label, and you're covered.

Serial number, model number, or service tag?

The label on a laptop usually carries several codes, and it's easy to copy the wrong one. The model number identifies the product line and is shared by thousands of identical machines, so it is useless for identifying yours. The serial number (often marked "S/N") is unique to your unit. Dell calls its equivalent a Service Tag, a short seven-character code, and HP labels carry both a serial number and a separate "product number" that describes the configuration. When in doubt, record the code marked S/N or Service Tag.

1. On the laptop itself

Turn the laptop over. Most manufacturers print the serial number on a sticker or laser-etch it into the bottom panel, near the regulatory markings. On MacBooks the text is tiny and etched along the edge nearest the hinge, so use your phone's camera and zoom in. Microsoft Surface devices hide it under the kickstand, and older laptops with removable batteries sometimes put it inside the battery bay.

Labels wear off. If yours is scratched or faded, the software methods below are more reliable, and it's worth recording the number while you still can.

2. In the operating system

Windows 10 and 11

Open PowerShell (right-click the Start button and choose Terminal or Windows PowerShell) and run:

Get-CimInstance -ClassName Win32_BIOS | Select-Object SerialNumber

You may see older guides recommend wmic bios get serialnumber. Microsoft has deprecated the WMIC tool and it is disabled by default on newer Windows 11 installs, so the PowerShell command is the one to use. Most manufacturers' own utilities, such as Lenovo Vantage, HP Support Assistant, MyASUS and Dell SupportAssist, also show the serial number or Service Tag on their main screen.

MacBook

Click the Apple menu and choose About This Mac. The serial number is listed on the first screen. You'll also find it under System Settings, General, About. If you use an Apple Account, every Mac signed in to it is listed with its serial number in the Devices section of your account settings, which is handy when the laptop itself is already gone.

Chromebook

Chromebooks are best checked on the label underneath or on the original box. School and work Chromebooks are often also recorded by the organisation's IT team, so ask them if the label is missing.

3. When the laptop won't turn on (or is already gone)

If the laptop still powers on but Windows won't load, the BIOS or UEFI setup screen (usually reached by tapping F2, F10, F12 or Delete at start-up, depending on the brand) shows the serial number on its main or information page on most machines.

If the laptop is dead, lost or stolen, look at the original box (the serial is printed beside a barcode on the outer label), your tax invoice or receipt, your warranty registration email, and your Apple, Microsoft or manufacturer account. Retailers can often reprint an invoice with the serial number if you bought from them on a loyalty account.

Checking a second-hand laptop before you buy

Laptops are among the most commonly stolen items in Australian homes and cars, and they resell quickly on Facebook Marketplace and Gumtree. A few minutes with the serial number protects you from buying one, and from losing your money when the police or the real owner come looking for it.

1. Ask for the serial number before you meet. A genuine seller has no reason to refuse. Run it through the SerialCheck search to see whether it has been reported stolen.
2. Compare the label with the software. When you inspect the laptop, check that the serial on the case matches the one Windows or macOS reports. A mismatch isn't always sinister (a replaced motherboard can blank or change the software serial), but it deserves an explanation and a repair invoice.
3. Look it up with the manufacturer. Apple's coverage check, and the warranty pages from Dell, HP, Lenovo and most other brands, will tell you the exact model a serial belongs to. If the listing says 32 GB of memory and the serial comes back as a 16 GB model, walk away.
4. Watch for locks you can't remove. A MacBook tied to someone else's Apple Account with Find My turned on is protected by Activation Lock and can't be set up as yours. Ask the seller to sign out of their Apple Account and erase the Mac in front of you. For Windows laptops, be wary of a BIOS password the seller "can't remember", or a setup screen that asks you to sign in with a company account. That usually means an ex-corporate machine still enrolled in its former employer's device management.
5. Trust the usual warning signs. A price well below market, no charger or box, a seller who won't let you see it running, or pressure to pay before inspecting are all reasons to pass. Our guide to buying safely on Marketplace and Gumtree covers the rest.

Buying stolen goods can cost you the item and the money you paid for it, even if you had no idea. We explain why in why you should always check the serial number before buying second-hand.

If your laptop is stolen

Report it to police with the serial number, make, model and any distinguishing marks. Use Find My (Mac) or Find my device (Windows, if you turned it on) to locate or lock it, and change the passwords for any accounts that were signed in. Then mark it stolen on SerialCheck so anyone who checks the serial is warned. Our step-by-step guide on what to do if your property is stolen walks through police reports and insurance claims in detail.

Record it today

Finding the serial number takes a minute now and can save weeks of trouble later. Photograph the label, then register your laptop on SerialCheck so there's a timestamped record of ownership if you ever need it. For phones, bikes, tools and everything else in the house, see our guide to where to find serial numbers on common items.