How to check a used laptop before buying

Before you go

To work through every check

~15 min

Checks in the list below

18

Of them have a Tapcheck test to open

11

Ask the seller to have the laptop charged, signed in and connected to Wi-Fi or a phone hotspot. Bring headphones, a USB stick and, if possible, your own charger. Note the exact model and specs from the listing so you can check them.

Tick each item off as you go. The sections below explain how to do each one.

1. Check the specs match the listing

Open system specs to see the processor, graphics, screen resolution and operating system. On Windows, Settings then System then About also shows the processor and installed memory. On a Mac, Apple menu then About This Mac. Check they match what you're paying for.

2. Screen

Run the dead pixel test. Look at each solid colour in full screen for dead or stuck pixels, then use the black fill with brightness up to check for backlight bleed at the edges. Tilt the lid and look for flicker or lines, which can mean a damaged display cable.

3. Keyboard and trackpad

Press every key in the laptop keyboard test. Keys that never light up, or a whole row that fails together, often mean liquid damage. Then open the touch test and draw across the whole trackpad, try two-finger scrolling and pinching, and press the trackpad in each corner to check it clicks.

4. Battery

Open the battery check, unplug the charger and confirm the status changes. Battery wear isn't visible to a browser, so check it in the system:

• Windows: open Command Prompt, run powercfg /batteryreport, and open the report it saves. Compare Full charge capacity with Design capacity. Much below about 80% means a weak battery.
• Mac: hold Option, click the Apple menu, choose System Information, then Power. Check Cycle Count and Condition.

5. Speakers, microphone and webcam

Play tones in the sound test and pan left and right to confirm both speakers work without rattling. Record a clip in the microphone test and play it back. Open the webcam test to check the camera turns on and the image is clear.

6. Ports, Wi-Fi and charging

Plug your USB stick into every port and check each one is recognised. Run the network test to confirm Wi-Fi connects and stays stable. Check the charger is the correct wattage for the model and that the laptop charges from it.

7. Run the full diagnostic

Finish with the full diagnostic, which runs ten automated checks across the display, graphics, audio, battery, processor, memory and input in about a minute, and gives you a report you can save.

8. Make sure it's really theirs to sell

• Mac: ask the seller to sign out of their Apple ID and turn off Find My in front of you. A Mac with Activation Lock on can't be set up by you.
• Windows: ask the seller to reset the laptop, or at least confirm there's no BIOS or firmware password.
• Check the hinges, case and screen for cracks, and look at the screws for signs it's been opened.