Dead pixel test — backlight bleed and colour uniformity
Thirty seconds on a new monitor. Do it while you can still return it.
Check a monitor for dead and stuck pixels using full-screen solid colours, and look for backlight bleed and uneven brightness at the same time.
Pick a colour and it opens full screen. Click the screen for the next colour, Esc to leave. There are no ads in full screen.
What a dead pixel test actually shows
A solid colour fills every working pixel with the same value, so a single wrong one stands out immediately. A bright dot on a black screen is a stuck pixel; a black dot on a white screen is a dead pixel. A stuck pixel has one subpixel frozen, so stepping through red, green and blue tells you which channel is jammed.
Whether you can get it exchanged
Manufacturer thresholds vary, and most are written in terms of how many bright dots and where they sit — which means one or two often does not qualify. The retailer's no-reason return window (commonly 7 days) is usually far more generous, so running this test the moment the monitor arrives is what actually protects you.
Bleed and uniformity
On a black screen in a dark room you will see the corners glow. On IPS panels that is normal to a degree, and the test is whether it bothers you looking at the screen straight on. Blotchy shading on the white and grey screens is a backlight uniformity problem instead.
Before you start
Clean the screen. Dust and fingerprints get mistaken for dead pixels constantly. Check that browser zoom is at 100%, and on a laptop turn off adaptive brightness first.
The conditions that make faults visible
Bright room lighting reflects off the panel and swallows small dots. Darken the room and look straight on. Viewing at an angle produces the colour shift IPS panels are known for, which reads as blotching and leads to false conclusions. Sit at your normal working distance — a dot you can only find with your nose against the glass will never bother you in use.
Telling dust from a dead pixel
This is the most common misdiagnosis. Wipe the screen with a soft cloth and look again. If it survives, cycle the colours and watch how the dot behaves. Dust sits in the same place with the same shape on every colour; a faulty pixel appears and disappears depending on the colour. Bright only on black is a stuck pixel; black only on white is a dead one.
Stuck pixels sometimes recover
Because a subpixel is frozen at one value, cycling colours quickly can shake it loose. If hours of cycling changes nothing, the defect is physical and you should be pursuing an exchange. Do not press on the panel — it can damage neighbouring pixels, and a pressure mark removes your grounds for exchange entirely.
How much backlight bleed is normal
IPS panels cannot block light completely, so dark screens glow at the corners. Some of that is expected, and the standard is "does it bother me at a normal brightness, viewed straight on" — a pitch-black room at maximum brightness is not a realistic condition. What is a defect: light escaping from one corner like a torch, or a bright band running across the panel.
Do it the day it arrives — the window is everything
Manufacturer dead-pixel policies are usually written around count and position, so one or two dots frequently fall short of the threshold. The retailer's change-of-mind return window (commonly 7 days) asks for no reason at all. That window is your real protection. Run this test as soon as you unbox, and photograph the screen if you find anything.
Read next
If the pixels are fine but two monitors disagree on colour, the calibration tool gives you reference screens to match them by eye.
Frequently asked
I found one dot. Can I get it exchanged?
Manufacturer policies are usually written around count and position, so one or two dots often fall short of the threshold. The retailer’s change-of-mind return window (commonly 7 days) asks for no reason at all, which makes it your strongest option in practice — so check the moment you unbox.
How do I tell dust from a dead pixel?
Wipe the screen and look again. If it survives, cycle through the solid colours and watch it. Dust sits in the same place with the same shape on every colour; a faulty pixel appears and disappears depending on the colour.
The corners glow. Is that a defect?
IPS panels cannot block light completely, so dark screens glow at the edges. Some of that is normal, and the test is whether it bothers you at normal brightness viewed straight on. Light escaping from a corner like a torch, or a bright band across the panel, is a defect.