🟦 Dead Pixel · Color · Motion · Refresh Rate
Screen Health Test
Check for dead/stuck pixels, backlight bleed, color accuracy, motion blur
and refresh rate — all free, in your browser, no download needed.
New to checking your screen? Read the
step-by-step guide
first, or dive straight into the tests below.
What This Screen Test Actually Checks
This tool shows your display clean, full-screen reference colors and
patterns — the same principle used by dedicated dead pixel checkers. A
browser cannot read back what your screen is physically displaying, so
spotting a dead pixel, stuck pixel, or backlight bleed still requires your
own eyes; this tool's job is to give you the cleanest possible reference
to check against.
What Makes This Different
🎯
One-click full sequence
Most dead pixel checkers make you click through colors manually. Our
Full Screen Health Check runs all 11 steps automatically and times
each one for you.
📤
Exportable results
Export your results as PDF, CSV, or JSON to compare panels or share
with a seller before buying used hardware.
🔒
Nothing leaves your device
Every test runs fully client-side. No signup, no accounts, no data
sent anywhere.
Dead Pixel vs Stuck Pixel
A dead pixel stays permanently black on every color — it isn't
receiving any power. A stuck pixel stays fixed on one color
(often red, green, or blue) because a single sub-pixel is stuck on. Run the
black, white, red, green, and blue screens above one at a time — a dead pixel
shows as a dark dot on white/color screens; a stuck pixel shows as a colored
dot on the black screen.
⚫
Backlight Bleed
Run the black screen in a dark room at full brightness. Look for
glowing patches near the edges or corners.
🌈
Color Banding — 6-bit vs 8-bit
The banding ramp reveals visible steps instead of a smooth gradient.
Cheaper laptop panels are often true 6-bit (or 6-bit + FRC dithering)
rather than true 8-bit — this shows up as harder edges in the
gradient, especially in dark grays. Heavy banding here often means a
lower bit-depth panel or GPU dithering turned off.
📐
Screen Uniformity
The 50% gray screen reveals patchy brightness or a color tint across
the panel that's invisible on regular content.
🎞️
Motion Blur
Watch the moving blocks without following them with your eyes —
trailing/ghosting is more visible on slower-response panels.
📐
Viewing Angle Shift
TN panels shift color and contrast sharply off-angle; IPS panels stay
stable. Tilt your screen slightly while on the Uniformity test to
check which type you have.
Checking for PWM Flicker
Browsers cannot detect PWM (Pulse-Width Modulation) flicker directly — it
happens at the hardware backlight level, faster than any web API can
measure. But you can check for it yourself in under a minute:
📱
Camera Slow-Motion Method
Open your phone camera, switch to slow-motion video mode, set this
tool's brightness swatch to Gray, dim your laptop brightness to around
30–50%, and film the screen. Horizontal dark bands scrolling through
the recording indicate PWM flicker.
✋
Quick Wave Test
With the Gray swatch open, wave a pen or your finger quickly in front
of the screen at low brightness. A smooth blur means no visible
flicker; a stuttering, strobing trail suggests PWM at low brightness
levels.
👁️
Why It Matters
PWM flicker is usually invisible to the naked eye but can contribute
to eye strain or headaches for sensitive users, especially at lower
brightness settings where flicker frequency often drops.
Frequently Asked Questions
What is a dead pixel vs a stuck pixel?
A dead pixel stays permanently black — it receives no power at all. A
stuck pixel stays fixed on one color (usually red, green, or blue)
because one sub-pixel is stuck on while others are off. Stuck pixels
can sometimes be fixed with pressure or flickering methods; dead
pixels usually cannot.
Can a browser detect dead pixels automatically?
No. A browser has no way to read back what your screen is physically
displaying — it can only show you solid colors to look at. Detecting a
dead or stuck pixel still requires your eyes; this tool's job is to
give you clean, full-screen reference colors to check against.
What is backlight bleed and how do I check for it?
Backlight bleed is light leaking around the edges or corners of an LCD
panel, most visible on a full black screen in a dark room. Run the
black screen test, dim your room lights, and look for uneven glowing
patches near the bezel.
Why does my screen look slightly different in this test than in real
use?
Browser color rendering depends on your display's color profile, OS
color management, and any blue-light/night-mode filters running. For
the most accurate test, disable night light mode and run this test at
100% brightness in a dim room.
Is this the same as a hardware dead pixel checker?
It follows the same principle as dedicated hardware checkers —
full-screen solid colors — but runs entirely in your browser with no
download. For panels you suspect have an issue, testing in a dark room
at full brightness gives the most reliable result.