Used Device Buying Checklist
The fifteen checks worth doing before handing over money for a used device.
The device is signed out of the seller's accountdeal-breaker
Check for an activation lock, a BIOS or firmware password, and a Find My or device-management enrolment. Ask them to sign out in front of you.
The battery is not swollendeal-breaker
A trackpad that no longer clicks flat, a case that will not sit level on a table, or a lifting keyboard. Look at the machine from the side.
The serial number matches the listing and the boxdeal-breaker
Compare the serial in the system information against the sticker and anything the seller has shown you. A mismatch is worth an explanation.
It boots to a working desktop without errors
Watch a full cold boot rather than waking it from sleep. Errors during startup are the ones sellers avoid showing.
The screen has no dead pixels, cracks or backlight bleed
Run the dead pixel test on this site full screen, and look at a black image in a dark room for bleed.
Every key registers
Use the keyboard tester on this site. Sticky or dead keys are common on machines that have had a drink spilled in them.
The trackpad clicks and tracks across its whole surface
Drag slowly into each corner and click in each one. A trackpad that clicks unevenly is often the battery underneath it.
Every port works
Take a USB stick, a charger and a display cable with you and try each socket. Charging ports fail more often than anything else.
The battery holds a reasonable share of its original capacity
Check the capacity figures the operating system reports, or run the battery report interpreter on this site.
The drive reports no reallocated or pending sectors
Read the SMART attributes with any disk utility, or paste the report into the interpreters on this site.
It does not overheat or throttle under load
Run the CPU stress test on this site for a few minutes and listen. A fan at full speed within a minute of idle is a dust or paste problem.
Wi-Fi and Bluetooth both connect
Join a network and pair something. A machine that has never been connected during a viewing is worth being curious about.
Camera, microphone and speakers all work
Use the webcam, microphone and speaker tests on this site. Two minutes covers all three.
The operating system is properly licensed and freshly installed
A machine sold with someone else's account still signed in has not been prepared, and you cannot tell what is on it.
The case, hinges and screen mount are sound
Open and close the lid slowly. A hinge that catches, or a case that flexes at the corner, indicates a drop.
How this calculation works
Work down the list while you have the device in front of you and mark each check. Three of them are deal-breakers and are handled separately from the score: an activation lock, a swollen battery and a serial that does not match are not matters of degree, and a scoring model that averages them away would tell you to buy something you should walk away from. Everything else is weighted — a failing drive matters more than a dead webcam — and averaged over what you actually checked, so skipping items lowers confidence rather than flattering the result. Each failure carries what it costs to put right, which is the number to negotiate with.
What the results mean
- Deal-breaker
- Ends the assessment regardless of the score. Locked to an account, a swollen cell, or a serial that does not match the listing.
- Score
- Weighted across the non-fatal checks you answered. Storage, screen and boot behaviour carry more weight than a webcam.
- Checked, of total
- How much of the list you got through. Below half, the tool declines to conclude anything.
- What it costs
- Every failure carries the repair it implies, so a discount can be argued from a number rather than a feeling.
Common problems and fixes
- The seller will not let me test it
- That is itself the answer. Every check here takes a couple of minutes, and a seller with nothing to hide has no reason to refuse.
- It is a remote sale with photographs only
- You can verify almost none of this. Price it as unknown-condition and use a payment method with buyer protection.
- It is cheap enough that I will take the risk
- Fine for the weighted items. Not for the deal-breakers: a locked device is worth its scrap value, and a swollen battery is a fire risk rather than a discount.
Frequently asked questions
What should I check when buying a used laptop?
Three things that should end the viewing if they fail — that it is signed out of the seller's account and carries no firmware password, that the battery is not swollen, and that the serial matches the listing — and then the ordinary condition checks: a clean cold boot, the screen, every key, the trackpad, every port, the drive's SMART attributes, and behaviour under load. The tests for most of those are on this site and take about ten minutes together.
How do I know if a used laptop is stolen?
You cannot know for certain, and there are strong signals. A device still signed in to somebody else's account, a firmware or BIOS password nobody can remove, a serial that does not match the listing or the box, and a seller unwilling to demonstrate a sign-out are each reason enough to walk away — and the first two make the machine unusable regardless of its history.
What is a swollen battery and why does it matter?
A lithium cell that has gassed internally and expanded. The signs are a trackpad that no longer clicks flat, a case that will not sit level, or a lifting keyboard. It is a fire risk rather than a wear item — it should not be carried on a plane, and it needs replacing before the machine is used rather than after.
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