Used Monitor Test
A five-minute checklist for an in-person second-hand purchase.
Best run in fullscreen with consistent room lighting · About 5 minutes · 4 recommended steps
Confirm the basics first.
These are browser-reported values. They describe the active display environment and can be affected by scaling.
Browser-reported display
Detecting display information…
What this inspection covers
5 checks in this order. Pause after any step; your session stays in this browser until you finish.
- Recommended
Resolution Checker
See the active screen, viewport, device pixel ratio and browser display capabilities.
- Recommended
Dead Pixel Test
Cycle through the solid colors and scan the entire panel for pixels that stay dark, bright or off-color.
- Recommended
Backlight Bleed Test
Dim the room and view the black field straight on. Note fixed bright areas near the edges, then judge them at the seller's usual brightness.
- Optional
Color Banding Test
Check the smooth gradients for abrupt steps, especially in dark tones.
- Recommended
Refresh Rate Test
Estimate active refresh timing from browser animation frames.
Frequently asked questions
Can I inspect a used monitor before I pay for it?
Yes. The inspection runs in a browser you bring along, so you can complete the essential checks at the seller's location in a few minutes.
What matters most when checking a used monitor?
Pixels that stay lit or dark, bright edge areas and large uneven patches are hard to fix later. Record what you see and weigh it against the asking price.
Is this inspection enough to judge long-term reliability?
No. It covers what you can observe on site in minutes. Aging behavior and long-term uniformity only show over time, and remain your own observation.