This monitor test runs 17 full screen patterns that show the faults a new or second hand screen can have: dead and stuck pixels, uneven backlight, color banding, wrong gamma, crushed shadows, blurry text and narrow viewing angles. Each pattern comes with a one line description of what a good screen shows, so you know what to look for without reading a manual. It works with any monitor, laptop screen or TV connected to a computer, in a browser on Windows, Mac, ChromeOS and Linux, and every pattern is drawn at the screen's native resolution, one browser pixel to one screen pixel. It also makes a quick screen tester for a used monitor before you pay for it.
How to test a monitor
- Let the monitor warm up for about 30 minutes if you want to judge colors and evenness. Pixel faults show at once.
- Set the computer to the monitor's native resolution. In Windows that is the resolution marked Recommended in Settings, then System, then Display.
- Pick the monitor's standard or sRGB picture mode, and turn off dynamic contrast, eco modes and Night Light, which change brightness while you test.
- Press Start full screen test. Step through the patterns with Space, a click or a swipe, and read the short line at the top of each one.
- If something looks wrong, press M and click on it. The spot map keeps its position and the pattern it showed on.
- Press Esc to finish and Copy report if you need to show the results to a seller or a support desk.
What each pattern checks
| Pattern | What it checks | A good screen shows |
|---|---|---|
| Setup chart | Edges, scaling, geometry, grey steps, clipping | The edge line on all four sides, round circles, 11 distinct steps |
| Black, white, red, green, blue | Dead, stuck and hot pixels | No dots that differ from the rest |
| Grey 50% and Uniformity | Backlight evenness and tint | An even grey, with corners no more than slightly darker |
| Gradients | Banding and color cast | Smooth ramps and a neutral grey band |
| Grey steps | Grey scale tracking | 11 neutral steps, each clearly different |
| Gamma | Midtone brightness | The 2.2 patch blending into its stripes |
| Black level | Brightness setting, shadow detail | Squares 3 to 20 visible on black |
| White level | Contrast setting, highlight clipping | Squares up to about 250 visible on white |
| Text and Sharpness | Scaling and the sharpness setting | Crisp text with no blur and no bright outlines |
| Viewing angle | How the panel type behaves off center | Small changes as you move your head |
| Pixel checkerboard | 1:1 pixel mapping and inversion | Flat grey from a distance, no flicker |
Dots that stay lit or stay black
A dot that shows on black but not on other colors is a stuck pixel. A dot that is black on every color is dead. Mark each one, then switch the set to Dead pixel colors or open the dead pixel tester, which explains what each kind of dot means and how many a maker allows under warranty.
Stripes in the gradients
Visible steps in a gradient are called banding. In order of likelihood:
- A color profile or calibration curve. Profiles that adjust the graphics card's output reduce the number of shades it can send. Remove custom profiles in Color Management on Windows, or choose the monitor's default profile in Displays settings on a Mac, and test again.
- Graphics card color settings. Set the output to RGB at 8 or 10 bits per color. In the NVIDIA Control Panel this is under Change resolution, with Use NVIDIA color settings.
- A 6 bit panel. Budget panels show 6 bits per color and fake the rest by flickering between shades, which leaves soft bands. Nothing fixes that except a better panel.
- Scaling and picture modes. A non native resolution, a game or movie preset and some HDR modes add banding. Return to native resolution and the standard mode.
Patches, tints or blotches on grey
Darker corners, a brighter band at one edge, or a cloudy patch on the grey patterns are uniformity faults. Most LCDs are a little darker in the corners, so compare zones on the Uniformity pattern and judge what you notice in normal use, not just on a test pattern. Light leaking at the edges on black is backlight bleed, covered on the backlight bleed test monitor page. On OLED and VA screens, vertical bands on dark grey are a known panel trait called the dirty screen effect.
Blacks look grey, or shadows vanish
On the Black level pattern you should see square 3 and up. If the first 10 or more squares melt into black, or the black background looks grey, the computer and monitor probably disagree about the color range. Over HDMI, graphics cards sometimes send limited range, where black is level 16 instead of 0:
- NVIDIA: set Output dynamic range to Full in the NVIDIA Control Panel.
- AMD: in AMD Software, under Display, set Pixel Format to RGB 4:4:4 Pixel Format PC Standard (Full RGB).
- Intel: set Quantization Range to Full in Intel Graphics Software, or in Intel Graphics Command Center on older drivers.
- On the monitor, set the HDMI black level or RGB range option to match, then fine tune with the Brightness control.
Colors look washed out or too strong
Wide gamut monitors show ordinary web colors oversaturated unless something converts them, so skin looks sunburned and greens look neon. Switch the monitor to its sRGB mode, which most wide gamut models have. The opposite, washed out colors, often comes from Windows HDR being on for desktop work or from the limited range problem above. The screen color test has more patterns for judging color, and the hdr test shows whether HDR is on.
Text looks blurry or has halos
- Not at native resolution. The monitor stretches the picture and every edge softens. Set the Recommended resolution.
- Sharpness too high. Bright or dark outlines around letters and around the squares in the Sharpness pattern. Lower the monitor's sharpness until they disappear. Many monitors look best at their default or one step below.
- ClearType not tuned. On Windows, search for Adjust ClearType text and follow the five steps.
- High pixel density. On 4K monitors at small sizes, scaling of 150% or 200% gives the cleanest text. The 4k monitor test shows whether every pixel reaches the screen.
Colors change when you move your head
That is how the panel type behaves, not a fault. TN panels darken or invert when seen from below. VA panels lose shadow detail and shift color from the side. IPS panels keep color well but glow in the corners on dark scenes. OLED changes least, with a slight tint at steep angles.
Motion, refresh rate and flicker
These patterns are still images. For motion, run the ufo test for blur and ghosting, and the refresh rate test to confirm your 144 or 240 Hz screen really runs at that rate. If the picture flickers or blinks on its own, the guide to monitor flickering goes through cables, refresh rate settings and drivers.
What a browser monitor test cannot measure
A web page cannot measure brightness in nits, contrast ratio or color accuracy. Those need a colorimeter, which reads the light coming off the screen. The patterns here make faults visible so your eyes can judge them, which covers almost everything that decides whether to keep or return a monitor. The page reads the resolution and color range your browser reports, and the readouts show them, but it cannot read the panel type or model.
Monitor test questions
How do I check if my monitor is working properly?
Run the full set of patterns here at the monitor's native resolution. A healthy screen shows no dots that differ from the rest, smooth gradients, an even grey, distinct dark and light squares and sharp text. Then check motion with a refresh rate and UFO test.
What should I test on a new monitor?
Dead and stuck pixels, backlight bleed, uniformity on grey, banding in gradients and the refresh rate. Test within the store's return window, because a panel fault is far easier to return than to claim under warranty.
Is this an LCD test as well?
Yes. The patterns work the same on LCD, OLED and mini LED screens. LCDs are more likely to show bleed, glow and uneven grey. OLEDs are more likely to show near black banding and burn-in.
Why does text look blurry on my monitor?
Usually because the computer is not sending the monitor's native resolution, so the monitor scales the picture. Set the resolution marked Recommended in Windows, or the default in macOS, then run the Text pattern again. Too much sharpness causes bright outlines instead of blur.
How long should a monitor warm up before testing?
About 30 minutes for colors and brightness to settle. Dead pixels and bleed show straight away, but uniformity and color judgments are fairer on a warm screen.