How to Find a Serial Number on a Laptop

Every laptop has a unique serial number — a manufacturer-assigned identifier that's essential for warranty claims, repair requests, insurance documentation, and even recovering a stolen device. The challenge is that where to find it depends heavily on your laptop brand, operating system, and whether you still have the original packaging.

Here's a practical breakdown of every method, so you can find yours regardless of your situation.

Why Your Laptop Serial Number Matters

A serial number is more than an inventory tag. Manufacturers use it to track your specific unit's production details, warranty status, and eligible repairs. If you ever need to contact support, order a replacement part, or register your device with an extended warranty provider, the serial number is the first thing you'll be asked for.

It also serves as a unique fingerprint for insurance claims or police reports if a laptop is lost or stolen — making it worth recording somewhere separate from the device itself.

Method 1: Check the Physical Label on the Laptop

The most straightforward place to start is the laptop itself. Most manufacturers print the serial number on a sticker or engraving on the bottom panel of the device.

What to look for:

• A label containing a barcode or QR code
• Text labeled "S/N", "Serial No.", or "Serial Number"
• It may appear alongside other identifiers like the model number, product number, and regulatory markings

On Dell laptops, this is typically a small label with a Service Tag, which functions as the serial number for their support system. On HP devices, the serial number often appears near the product number and may be labeled "S/N" in small print. Lenovo laptops usually have a label near the battery compartment or on the base.

If the label is worn, scratched, or missing — which happens on older or heavily used machines — software-based methods are more reliable.

Method 2: Find It Through the Operating System

You don't need to flip your laptop over. Every major OS can retrieve the serial number from firmware.

Windows

Open Command Prompt (search "cmd" in the Start menu) and run:

wmic bios get serialnumber 

The serial number will display directly in the terminal window. This pulls the value stored in the system's BIOS/UEFI firmware, which is typically set by the manufacturer at the factory.

Alternatively, open PowerShell and run:

Get-WmiObject -Class Win32_BIOS | Select-Object SerialNumber 

Both methods return the same result.

macOS 🍎

Click the Apple menu → About This Mac → System Report. Under the Hardware section, you'll see the Serial Number listed directly.

A faster route: open Terminal and run:

system_profiler SPHardwareDataType | grep Serial 

On newer Macs, the serial number is also visible directly in About This Mac without needing to open System Report.

Linux

Open a terminal and run:

sudo dmidecode -s system-serial-number 

This reads the value from the system DMI table, which most manufacturers populate during production.

One important caveat: On some laptops — particularly certain budget or white-label models — the BIOS serial number field may show as blank, "Default String," or "To Be Filled By O.E.M." In those cases, the physical label is your only reliable source.

Method 3: Check the BIOS/UEFI Directly

If you can't boot into Windows or your OS, you can access the serial number through the BIOS/UEFI setup screen.

Restart the laptop and press the appropriate key during startup — typically F2, F10, F12, Del, or Esc depending on the manufacturer. Once inside, navigate to the System Information or Main tab. The serial number is usually listed there alongside the model and firmware version.

This method is useful if you're troubleshooting a machine that won't fully boot, or if you're working on a laptop before the OS is installed.

Method 4: Original Packaging or Documentation

If you still have the original box, the serial number is printed on a label on the outside — often in multiple places. It also appears in:

• The purchase receipt or invoice from the retailer
• The manufacturer's warranty registration confirmation email
• The product registration card included in the box

If you registered the device with the manufacturer when you first set it up, you can often log into your account on their support portal and retrieve the serial number there without touching the physical laptop.

Comparing Methods at a Glance

When Software Methods Don't Match the Label

Occasionally, the serial number returned by the OS differs from what's printed on the bottom label. This can happen when:

• A motherboard has been replaced, and the new board wasn't programmed with the original serial number
• A third-party repair didn't update the BIOS fields correctly
• The device was refurbished and reassigned a new identifier

For warranty and manufacturer support purposes, the physical label or original documentation is usually treated as the authoritative source. If those conflict with what software reports, it's worth contacting the manufacturer before submitting a service request, since using the wrong number can delay or invalidate a claim.

Variables That Affect Where You'll Find It

Not every method works equally well for every laptop. The factors that shape your experience include:

• Brand: Dell's Service Tag system differs from HP's product numbering or Apple's serial format
• Age of the device: Older labels wear down; very old BIOS implementations may not store serial numbers in readable fields
• Hardware modifications: Replaced motherboards or unofficial repairs can break the software-to-label connection
• OS availability: A machine that won't boot limits you to physical or BIOS methods
• Refurbishment status: Refurbished laptops sometimes have missing or altered labels

The right method for your situation depends on which of these variables apply to your specific machine — and whether you need the number right now for a support call, or want to record it somewhere safe for future use.