Monitor Response Time & Ghosting Test
A striped block moves across your screen so you can watch for ghosting, motion blur and overshoot in real time. Pick a speed and a background, and watch what trails behind it.
Speed
Background
Keyboard Shortcuts: Space to pause/resume, 1/2/3 for speed, F for fullscreen.
Found a stuck pixel? Try to revive it with the Dead Pixel Fixer
How to Use This Tool
What is this Test?
This test moves a striped block across the screen so you can visually check for ghosting (a trailing smear behind moving objects) and motion blur. It's a visual check, not a measurement device - true pixel response time in milliseconds requires a high-speed camera or dedicated test hardware, which a browser cannot replicate. Use this to spot an obvious problem or compare settings, not to verify a manufacturer's millisecond spec.
Ghosting vs. Motion Blur
- Ghosting: a distinct, repeated trailing edge or double image behind a moving object - usually a pixel response time issue (the panel is too slow to fully switch color between frames)
- Motion blur: a smoother, more uniform smear across the whole moving object - common on any sample-and-hold display (most LCD/OLED monitors) and reduced by higher refresh rates, not just faster pixels
- Overshoot / inverse ghosting: a bright or dark halo that leads ahead of the moving object rather than trailing behind it - usually means the overdrive (OD) setting is too aggressive
What Actually Affects What You See
- Overdrive (OD) setting in your monitor's on-screen menu - usually labeled Off/Normal/Fast/Extreme - trades ghosting for overshoot risk as you increase it:
- Refresh rate vs. your GPU's actual frame rate - a 144Hz panel displaying a 60 FPS game will not look as smooth as the refresh rate alone suggests:
- Panel technology - budget VA panels are typically the slowest for dark-transition ghosting; modern IPS and TN panels are usually faster, though this varies significantly by model and price tier:
Testing Tips
- •Test at a few different speeds - a monitor can look fine at slow speeds and still show ghosting at fast ones
- •Try each overdrive setting in your monitor's menu while this test runs, and pick the one with the least visible ghosting and overshoot combined - most monitors ship with a sub-optimal default
- •Compare against a phone or second monitor if you have one - it is easy to misjudge motion artifacts without a reference point
- •A completely clean, trail-free result at high speed is not realistic on most LCD monitors - judge relative severity, not perfection
Keyboard Shortcuts
How this test works
A striped block moves across the screen by a fixed number of pixels on every screen refresh, using the browser's animation timing, so on a 144 Hz monitor it moves 144 times a second. Ghosting and overshoot show up as smears or halos behind and in front of the block. It is a visual check: the browser cannot measure pixel response time in milliseconds.
Pro Tip: If you see ghosting, check your monitor's overdrive setting before assuming the panel is defective: it is the most common fixable cause, and it's free to change. Checking a new monitor from top to bottom? The complete monitor test puts this test in order with the others.
One honest note up front: this is a visual check, not a lab measurement. A browser can't report a millisecond response-time figure - that needs a high-speed camera or dedicated test hardware. What it can do is show you, right now, whether your monitor's current settings produce visible ghosting.
What You're Actually Looking At
Ghosting
A distinct trailing edge or faint double image behind the block. Usually means the panel is too slow to fully switch color between frames.
Overshoot
A bright or dark halo that leads ahead of the block instead of trailing it. Almost always means your monitor's overdrive (OD) setting is too aggressive.
Motion Blur
A more uniform smear across the whole block. Common on any sample-and-hold display and reduced by a higher refresh rate, not just a faster panel.
Before You Blame the Monitor
Open your monitor's on-screen menu and check the overdrive setting (often labeled OD, Response Time, or Overdrive - Off/Normal/Fast/Extreme). Try each option while this test runs and pick whichever shows the least ghosting and the least overshoot together. It's the single most common fixable cause of visible ghosting, and most monitors don't ship on their best setting by default.
Frequently Asked Questions
Can this tool tell me my monitor's response time in milliseconds?
No. Measuring milliseconds needs a high-speed camera or dedicated test hardware. This tool is a visual check for ghosting and overshoot, useful for spotting a real problem or comparing settings, not for verifying a spec sheet number.
I see ghosting. Is my monitor defective?
Usually not. Check the overdrive setting in the monitor's on-screen menu first, because it is the most common fixable cause. If ghosting stays at every overdrive level and looks much worse than on similar monitors, that points to a real panel problem.
Which overdrive setting should I use?
Usually the middle one, often called Normal or Fast. The lowest setting leaves a dark trail behind moving objects, the highest adds a bright halo (overshoot). Try each level with this test and keep the one where the moving block looks cleanest.
Why does the trail change when I change overdrive?
Overdrive briefly pushes extra voltage to the pixels so they change color faster. Too little and you get ghosting, too much and the pixels overshoot the target color, which shows as a halo in front of or behind the object.
Does a higher refresh rate fix ghosting?
It reduces motion blur, because each frame is shown for a shorter time, but it doesn't fix true ghosting. Ghosting comes from how fast the pixels themselves change color, which is a panel response time issue.
Why does the moving block look choppy?
The animation runs at your screen's refresh rate. If it stutters, check that your display is set to its highest refresh rate in the system display settings, close other heavy tabs, and plug in a laptop so it doesn't throttle.
Written by R. Ottens, front-end developer & image editing specialist.