Monitor Test

A quick full-screen monitor test. Cycle solid colours, pure black and white, and grayscale steps to check any display for dead pixels, backlight bleed, colour uniformity and banding. Works on a monitor, laptop, phone or TV — nothing to install.

Press start, then step through each test screen with the arrow keys or the on-screen swatches. Solid colours check pixels and sub-pixels, black shows backlight bleed, and the grays reveal banding and uneven tint. Press Esc to exit.

Test screens
Best in a dark room at 100% brightness.

What a Monitor Test Checks

Each full-screen pattern isolates a different panel problem, so running through them all gives a fast, thorough picture of a display's health.

1

Pixels & sub-pixels

Solid red, green and blue expose dead and stuck pixels — the same check the dedicated dead pixel test automates. On white, look for dark specks; each colour should be perfectly even.

2

Black & backlight

A solid black screen in a dark room reveals backlight bleed and IPS glow near the edges. A little is normal; large bright clouds point to a panel defect.

3

Uniformity & banding

The white and grayscale steps show uneven brightness or a colour tint across the panel, and make banding — visible steps where shades should blend — easy to spot.

Frequently Asked Questions

What does an online monitor test check?
By filling the screen with solid colours, pure white, pure black and grayscale steps, it reveals dead and stuck pixels, backlight bleed and IPS glow on black, colour uniformity and tint across the panel, and banding in the grays. A quick, no-software check for a new or used display.
How do I check for backlight bleed?
Set the screen to solid black in a dark room and look at the edges and corners. Lighter glowing patches are backlight bleed or IPS glow. A little is normal; large bright clouds are a defect worth returning.
What is colour banding?
Banding is visible steps between shades that should blend smoothly. Viewing the grayscale steps here makes it easy to see and usually points to a lower bit-depth panel or an aggressive display setting.
Is anything uploaded or installed?
No. Everything runs in your browser — no upload, no account, nothing to install — and it works offline once loaded. See also the plain white screen and color screen.