How to use this test
- Measure your refresh rate first. This is measured from presented frames. Displays frequently run below their rating without saying so.
- Darken the room for the bleed test. Backlight bleed is only visible in a dark room. In daylight even a bad panel looks fine.
- Step through the patterns. Each targets one specific defect, and the note under each button says what to look for.
- Press Escape or click to exit. Patterns run fullscreen so browser chrome does not hide part of the panel.
Measured refresh rate, not claimed refresh rate
Start here, because this is the fault people most often have without knowing it.
A monitor rated at 144 Hz will happily run at 60 if nothing told it otherwise, and Windows sets that default on a new connection remarkably often. People game for months on expensive displays running at less than half their capability.
This test measures the rate at which frames are actually presented, rather than reading any reported value, because reported values reflect configuration and measured ones reflect reality. Laptops in particular drop to 60 Hz on battery without announcing it.
If the measured figure is lower than expected:
- Display settings. Windows: Display settings → Advanced display → choose the highest rate offered.
- The cable. HDMI 1.4 cannot carry 1440p or 4K at high refresh. DisplayPort usually can. This is the most common reason the high rate is not even offered.
- Mains power. Laptops commonly force 60 Hz on battery.
- The monitor menu. Some displays ship with their high refresh mode disabled and require enabling it on the device itself.
What each pattern is for
| Pattern | Look for | What it means |
|---|---|---|
| Backlight bleed | Brighter patches at the edges, in a dark room | Light escaping the panel edge. Some is normal on any edge-lit LCD. |
| Uniformity | Patches or tinting across flat grey | Uneven backlight or panel variation. Mild is normal; obvious patches are a defect. |
| Colour banding | Visible steps in a smooth gradient | Insufficient colour depth somewhere in the chain. |
| Sharpness | Anything other than flat grey | The image is not being displayed one-to-one. Usually scaling. |
| Colour bars | Wrong or washed-out colours | Colour profile or output range problem. |
| Motion clarity | A trail behind the moving block | Pixel response time. Panel-dependent and partly unavoidable. |
Bleed versus glow — the distinction that decides a return
These look similar and only one is a defect, so it is worth being able to tell them apart.
IPS glow is a silvery sheen at the corners that changes as you move your head. It is a property of how IPS panels handle light at an angle, it appears on every IPS display ever made, and it is not a fault.
Backlight bleed is fixed brighter patches, usually along an edge, that stay exactly where they are regardless of viewing angle. Severe bleed is a legitimate defect.
The test is simply to move your head. If the bright area shifts, it is glow. If it does not, it is bleed.
The sharpness pattern explained
This one confuses people, so it deserves a note. A 1-pixel checkerboard alternates black and white at the panel’s native resolution. When every pixel is displayed exactly as sent, your eye blends them into uniform grey.
If you see a visible grid, shimmering moiré, or coloured fringing, the image is not reaching your panel one-to-one — something is scaling or interpolating it. Common causes are running below native resolution, a display scaling mode stretching the image, or a sharpness control on the monitor set away from neutral.
Related tests
The dead pixel test covers individual pixel faults with full-screen solid colours, and the GPU benchmark measures whether your graphics hardware can actually sustain the refresh rate your display supports.
Frequently asked questions
Why is my monitor running at 60 Hz when it supports 144?
This is extremely common and almost always a setting rather than a fault. Windows frequently defaults to 60 Hz on a new connection and never changes it. Check Display settings, Advanced display, and select the highest rate offered. If the higher rate is not listed, the cable is the usual culprit — HDMI 1.4 cannot carry high refresh at 1440p or 4K, whereas DisplayPort generally can. Some monitors also need their high refresh mode enabled in the on-screen menu.
What is backlight bleed and is it a defect?
Bleed is light escaping around the edges of an LCD panel, visible as brighter patches on a black screen in a dark room. All edge-lit LCDs have some — it is inherent to the design, not a fault. It becomes a defect when it is severe enough to be visible during normal use, such as while watching a dark film. Mild bleed at the corners is normal and not usually grounds for a return.
What is the difference between backlight bleed and IPS glow?
IPS glow is a silvery haze visible at the corners that changes as you move your head, and it is a characteristic of the IPS technology itself rather than a defect. Backlight bleed is fixed brighter patches, usually at the edges, that do not change with viewing angle. The test: move your head. If it shifts, it is glow and it is normal. If it stays put, it is bleed.
Why does the sharpness pattern look like a colourful mess?
It should look like flat grey. A 1-pixel checkerboard alternates black and white at the panel’s native resolution, which the eye blends into uniform grey when each pixel is displayed exactly. If you see a visible pattern, moiré or colour fringing, your display is not showing the image at one-to-one scale — usually because it is not running at native resolution, or a scaling setting is interpolating the image.
What causes colour banding?
A gradient that shows visible steps instead of a smooth ramp means insufficient colour depth somewhere in the chain. Common causes are a 6-bit panel using dithering to simulate 8-bit, a display setting limiting output to a reduced colour range, or a cable or driver configured for a lower bit depth. Check your graphics driver output colour depth and colour format settings before assuming the panel is at fault.
My motion test shows smearing. Is my monitor bad?
Some smearing is normal and depends on panel technology — VA panels smear noticeably more than IPS or TN, particularly in dark scenes, and this is inherent rather than defective. Excessive smearing can sometimes be improved with an overdrive or response time setting in the monitor menu, though setting it too high causes inverse ghosting, which looks like a bright trail instead of a dark one. Moderate is usually the right choice.