Used Phone Inspection Checklist

What you need

The phone, a browser and ten minutes. No app to download, no account to create — every check here is a normal web page, which is what makes it practical to run on a device you do not own. Bring a known-good reference if you can: a second phone to compare the camera against, and somewhere quiet for the microphone. If a charger is included, keep it nearby, because one of these checks is done with the phone plugged in.

The order to test in

Work from the faults that end a deal toward the ones that only affect the price. The screen and the touch layer come first, because a dead zone or a large burn-in patch is the most expensive repair on a phone and usually a walk-away. Cameras, audio and sensors take under a minute each and tend to settle a negotiation point rather than the sale itself. Leave the permission-based checks for last, so the owner can see exactly what the browser is asking for and watch you decline anything they are not comfortable with.

Step 1 — Screen: dead pixels, burn-in and tint

Open the dead pixel test and step through the solid colours in a dim room. Black shows bright stuck pixels, white shows dark dead ones, and the three primary colours isolate each sub-pixel in turn. Look for haze or ghosting in one corner as well: on an OLED panel, a status bar or keyboard that has sat in the same place for years leaves a permanently brighter patch, and a solid grey screen is where it shows. A single dead pixel in a corner is a bargaining chip; a band of them, or visible burn-in, is a panel on its way out.

Step 2 — Touch: does it hold every finger?

Run the multi-touch test to answer two questions. First, whether every finger registers at once, which catches a digitizer that has partly failed. Second, and more useful, whether it holds them: press three fingers down, keep them still, and watch the counter. A healthy screen keeps the number at three; one that flickers to two and back is losing contact — the early symptom a seller will not mention and a repair shop will charge to find. Test the edges and corners as well as the middle, because that is where the touch layer fails first.

Step 3 — Touch: dead zones and ghost touch

A dead zone needs a different test, because a spot you never happen to press will not show up in any counter. Paint the whole screen slowly, edge to edge, with one finger in the touch dead-zone test. Anywhere your finger crossed that stays blank is a patch that is not registering touch. Then plug the phone in and leave it untouched on the table for a minute: lines that appear with nobody touching the glass are ghost touch, and they usually point at a failing digitizer or a charger injecting noise. Use the Export image button before you hand the phone back — a clean, gaping break in the line is far better evidence than a description.

Step 4 — Cameras: front and rear

Check both cameras, not just the one the seller demonstrates. The webcam test previews whichever camera the browser can reach and lets you switch between them, so run the selfie camera and the rear one, in light and in shadow. Look for dust inside the lens, a soft or smeared corner, and any purple or green cast that appears on only one of them. A slightly soft front camera is normal; a rear camera that is soft in one corner has been dropped.

Step 5 — Microphone

Record ten seconds with the microphone test and listen back on the phone's own speaker. Speak normally at arm's length, then again close to the mouth. What you are listening for is muffled speech, a hiss or hum sitting under the voice, or one side of a stereo pair that is silent. A microphone that works on speakerphone can still be dead on a normal call, because they are usually different microphones — check both.

Step 6 — Speaker and earpiece

Play the speaker test to catch a blown or buzzing driver, which is the fault it finds fastest: a damaged phone speaker rattles on bass, and the 20Hz–20kHz sweep walks straight into it. Note that the earpiece you hold to your ear is a separate speaker this test cannot drive, so make an actual call and listen to that one too. It is the most-used speaker on a phone and the one buyers forget.

Step 7 — Sensors and auto-rotate

Launch the sensor test and tap Start. Lay the phone flat and confirm the total reads about 9.8 m/s², then turn it onto each side and watch the big number move to a different axis; the total should stay near 9.8 throughout. Turn on auto-rotate and check the screen actually follows — a failing accelerometer shows up there first. Treat the compass gently: it drifts indoors, and some browsers report an angle from an arbitrary reference rather than true north, so compare it against a known compass outdoors before you call it a fault.

Step 8 — What a browser cannot check

Be honest about the limits. No web page can read battery health or cycle count, storage wear, or whether the phone is blacklisted or reported stolen — those live in system menus, carrier databases, or nowhere a page can reach. Nor can it see the internal water-damage indicators, whether the screen has been swapped for a cheap panel, or whether Face ID or Touch ID still works. Pair this checklist with the numbers the seller can show you in Settings, and ask for a live demonstration of anything biometric before money changes hands.

Turning the result into a price

Document as you go. The dead-zone test exports a picture, and the other pages keep their readings on screen for a screenshot. One clearly photographed fault is worth more in a negotiation than any amount of argument. If you are the seller, run the same list before you list the phone: a clean, dated pass is the cheapest way to justify your asking price and to answer a suspicious buyer.