Monitor Test
One guided sequence that checks the whole panel, then a checklist for everything that needs interaction. Turn the lights off first — several faults are invisible in a lit room.
Click or tap to advance · ←→ step · H hide overlay · Esc exit
Or jump straight to a screen:
Test checklist
- Dead and stuck pixels Individual dots that never change colour.
- Colour and banding Gradients should fade smoothly, with no steps or tint.
- Backlight bleed and clouding Light escaping at the edges of an LCD, seen on black.
- Burn-in and image retention A permanent ghost of something shown for a long time.
- Refresh rate Confirm the panel runs at the Hz you paid for.
- Ghosting and motion blur Trails behind moving objects, or halos in front of them.
- Touch response Dead zones and multi-touch, if the screen is a touchscreen.
- Resolution and size Check the panel reports the resolution and size it should.
Your verdicts stay in this browser — nothing is uploaded.
Test a monitor properly in five minutes
- Turn the lights off. The single most skipped step, and the one that decides whether you see backlight bleed and clouding at all.
- Clean the screen. A speck of dust is indistinguishable from a dead pixel until you wipe it.
- Set brightness to what you normally use. Testing at 100% exaggerates faults you will never notice in daily use.
- Run the fullscreen sequence and scan the entire panel on each field, corners included.
- Work down the checklist for refresh rate, ghosting and touch.
- Copy the summary if you need a record for a return, a warranty claim or a sale listing.
What each check finds
| Check | Fault it finds | Return-worthy? |
|---|---|---|
| Dead / stuck pixels | Dots that never change colour | Usually only above a threshold set by the maker |
| Backlight bleed | Light leaking at the edges of an LCD | Only if visible in normal use |
| Burn-in | A permanent ghost on OLED | Yes, if the panel is under warranty |
| Colour banding | Steps in a gradient | Mild is normal on 6-bit panels |
| Refresh rate | Panel not running at its rated Hz | Usually a settings fix, not a fault |
| Ghosting | Trails behind motion | Usually an overdrive setting |
Buying or selling a used monitor
This is the situation the summary is built for. Run the sequence on the seller's machine before money changes hands — dead pixels, burn-in and heavy bleed are the three faults that cost real money, and all three appear within the first minute of the black and white fields. If you are the seller, running it yourself and sharing the summary is a straightforward way to justify your asking price.
New monitor? Test it inside the return window
Panel faults do not develop — they arrive with the monitor. The return window is when you have leverage, and after it closes you are dealing with a warranty threshold that usually tolerates several dead subpixels. Test on day one, not day thirty.
One thing that is not a fault but is worth fixing immediately: high-refresh monitors very often ship set to 60 Hz. The refresh rate test tells you in a few seconds whether yours is running at its rated speed.
What a browser test cannot do
Anything visual is fair game — a solid colour field is the same whether a browser or an application draws it. What is out of reach is measurement: response time in milliseconds, colour accuracy in delta-E, and brightness in nits all need hardware. For finding faults, which is what almost everyone actually needs, none of that is required.
Every tool in the suite
Screen Resolution
Detect your display resolution, pixel ratio and viewport instantly.
Monitor Size
Work out your physical screen size in inches from its resolution and DPI.
Online Ruler
A calibrated ruler in actual size — cm, mm, inches or pixels.
FPS Test New
Live frame rate, 1% lows and stutter, with a frame-time graph.
Refresh Rate Test New
Measure the true refresh rate of your display in Hz, live.
Dead Pixel Test New
Fullscreen solid colours that expose dead, stuck and hot pixels.
Screen Colour Test New
Check colour accuracy, gradients, banding and panel uniformity.
Aspect Ratio Calculator New
Work out and resize any aspect ratio, with a live to-scale preview.
Burn-in Test New
Check OLED and LCD panels for image retention, and try to clear it.
Touch Screen Test New
Find dead zones and check multi-touch by drawing on the screen.
Backlight Bleed Test New
Find light leaking around the edges of an LCD panel.
Ghosting Test New
Check motion blur, trailing and pixel response with moving objects.
Screen Size Comparison New
Put two displays side by side, drawn to true scale.
Frequently asked questions
How do I test my monitor?
Run the guided sequence above in a dark room. It steps through ten full-screen fields that between them expose dead pixels, colour banding, backlight bleed and image retention. Then work down the checklist for the tests that need interaction — refresh rate, ghosting and touch. Mark each one as you go and the page builds a summary.
What should I check on a new monitor?
Do it before the return window closes. Dead pixels and backlight bleed are the two faults that justify a return, and both are easiest to spot in a dark room within the first hour. Also confirm the refresh rate is actually set to the panel maximum — monitors very often ship configured at 60 Hz.
How do I test a second-hand monitor before buying?
Open this page on the seller's device, run the sequence, and watch the black and white fields in particular. Dead pixels, burn-in and heavy bleed are the expensive faults and all three show up in under two minutes. The summary can be copied straight into a message if you want to negotiate.
Is a browser test as good as dedicated software?
For everything visual, yes — a solid colour field is a solid colour field whether a browser or an application draws it. What a browser cannot do is measure: it cannot report response time in milliseconds or colour accuracy in delta-E, because that needs a colorimeter. For finding faults, this is enough.
How long does the full test take?
About two minutes for the fullscreen sequence, and five or so if you work through the interactive tests as well. Turn the lights off first — several faults are invisible in a lit room.
Does my test result get saved or uploaded?
Your verdicts are stored in your own browser so the checklist survives a reload, and nothing is sent anywhere. Clearing your browser data removes them, and the Reset button clears them immediately.