Device check / 05
Monitor Test
Check a display for dead pixels, backlight bleed, colour banding, scaling blur, and the real refresh rate, full screen.
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Monitor Test: TOEA fills the screen with plain colours, a grey ramp, and a device-pixel checkerboard, and counts the frames the browser paints each second to report the refresh rate actually in use. Runs 100% locally in your browser with zero server file uploads.
- Category
- Everyday tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Go full screen, then step with → and ←, or Space. Esc leaves full screen. Dark spots are dead or stuck pixels; a yellow or dim area is uneven backlight.
Backlight bleed or panel glow
Judge the black screen in a dark room at the brightness you normally use, since maximum brightness exaggerates everything. Bleed is light leaking at the edges or corners that stays in the same place when you move your head. Glow, typical of IPS panels, is a haze that shifts or fades as you change your viewing angle or sit further back. Some glow is normal for the technology; bright, fixed patches that show during dark films or games are worth raising with the seller.
Stuck pixels and returns
A stuck pixel stays lit in one color, while a dead one stays black. Stuck pixels occasionally recover after several minutes of rapidly changing colors, but a dead pixel almost never does.
Test a new display straight away. Manufacturers' pixel policies often accept a small number of faulty pixels before offering a replacement, and the details differ by brand and model, while a retailer's return period is usually the simplest way to exchange a panel you are unhappy with.
How to use it
- Go full screen.
- Step through the colours, gradient, and checkerboard with the arrow keys.
- Read the refresh rate panel and compare it with the monitor's setting.
Privacy & limitations
Nothing leaves your browser. There is nothing to upload.
Related tools
Frequently asked questions
How do I find a dead pixel?
Full screen on white shows dark dots; black shows bright ones; red, green, and blue show a failed sub-pixel of that colour. Use the cycle option to sweep through them hands-free.
The gradient shows steps. Is the monitor faulty?
Slight banding is normal on 6-bit panels and over some cables. Heavy, uneven banding points to a colour profile or a cable at the limit of its bandwidth.
The checkerboard looks blurry or coloured.
The display is not being driven at its native resolution, or the operating system is scaling. The pattern is drawn at device pixels, so it should be perfectly sharp on a correctly set display.
The refresh rate is lower than the monitor's rating.
The browser paints at the rate the operating system gives it; a 144 Hz monitor set to 60 Hz in the system, or a laptop on battery saving, will show 60 here. Some browsers also cap background tabs.
Free tool · runs in your browser · no account required