What this phone test checks
This mobile test runs seven checks in your browser, one at a time. You judge some of them yourself. The others pass by themselves when the part responds.
- Screen: solid white, black, red, green and blue, to show dead pixels, lines and patches.
- Touch: a grid that fills where your finger passes, and a count of the fingers read at once.
- Speaker: a tone on the left, then the right, then both.
- Microphone: a live level meter, and a 3 second recording you can play back.
- Vibration: a short buzz pattern, on Android.
- Motion sensors: a dot that follows the phone as you tilt it.
- Cameras: a live view from the back camera and the front one.
Where the browser allows it, the page also shows the battery level. The sound from the microphone and the picture from the camera stay on your phone.
Screen test: white, black and colour screens
Each colour in this display test shows a different fault, so look at all five with the brightness turned up.
- White screen: dead pixels show as black dots. Look also for yellow or grey patches, dark corners and faint shadows of old images.
- Black screen: stuck pixels show as bright dots. On LCD screens, look for light leaking in at the edges.
- Red, green and blue screens: every pixel is made of three smaller lights, one for each of these colours. A dot that stays dark on only one colour has lost one of them. Thin lines of a single colour usually mean a damaged panel or connector.
Wipe the glass first. A speck of dust looks like a dead pixel until it moves.
Touch screen test
Slide a finger over every square of the grid. A square that will not fill, however slowly you go, is a dead spot. A dead band across the screen can follow a drop or a poor screen replacement. If squares near the edge will not fill, take off the screen guard and try again. The finger count shows multi-touch: most phones read at least five fingers at once.
Speaker and microphone test
The speaker test plays a rising tone on the left channel, then the right, then both. Listen for crackle, buzzing or a side that is much quieter. Phones with one speaker play both channels through it. Before you mark it as failed, check that the phone is not on silent and that Bluetooth earbuds are disconnected.
The mic test shows how loud the phone hears you. If the meter does not move when you speak, check that the microphone hole is not blocked by a case or by dirt. The recording you can play back is held in the page's memory and is gone when you close the check.
What it cannot check
A web page has no access to these, so check them yourself:
- Battery health. The page can show the level, not how worn the battery is.
- IMEI or blacklist status, and whether the phone is locked to a network.
- Water damage inside the phone.
- The charging port, the buttons and the fingerprint sensor.
Checking a second-hand phone before you pay
- Run the checks on this page, on the phone you are buying.
- Dial *#06# and compare the IMEI with the box and the bill.
- Make sure the previous owner's Google or Apple account has been removed, so the phone is not locked to it.
- Plug in a charger and see that it charges.
- Put your SIM in and make a call.
- On an iPhone, look at Settings > Battery > Battery Health.
Frequently asked questions
Is the phone test free, and do I need an app?
It is free. There is no app, no sign-up and no ads. It runs in the browser you already have.
Does it work on iPhone?
Yes, except the vibration test: iPhone browsers do not allow web pages to vibrate the phone. The microphone, camera and motion sensor checks ask for permission first. Safari keeps its bars on screen during the screen test, so repeat it with the phone turned sideways to see the strips they cover.
Why does it ask for the microphone and camera?
The browser will not let any page use them without asking you. The sound and the picture are used only on your phone, to draw the level meter and the preview. Nothing is recorded to a server or uploaded, and both are switched off when you close the check.
Can it check battery health?
No. A browser cannot read battery health. On an iPhone, look at Settings > Battery > Battery Health. On Android, look for battery information in Settings. Where it sits depends on the brand.
What is a dead pixel, and can it be fixed?
A dead pixel gets no power and stays black on every colour. It usually cannot be fixed without replacing the screen. A stuck pixel stays lit in one colour and sometimes clears by itself.
Does a failed check mean the phone is faulty?
Not always. Browsers block some features, and browsers inside apps such as Instagram can block more. Open the page in Chrome or Safari, check the phone's own settings (silent mode, permissions, battery saver) and run the check again before you decide.
