Ghosting test
The ghosting test moves shapes across black, gray and white so you can spot trails, halos, smearing and blur. No install needed.
Follow a shape with your eyes. A faint copy trailing behind it is ghosting. Try each overdrive level in your monitor’s menu.
Runs in your browser. Test data stays on your device.
- Refresh rate
- –
- Dropped frames
- –
- Speed
- 960px/sWhole pixels per frame
- Background
- All threeBlack, gray, white
Your observations
- Ghosting
- Not checked
- Overshoot
- Not checked
- Black smearing
- Not checked
- Motion blur
- Not checked
After each preset, choose what you see under the test.
Presets answered: 0 of 4
A web page cannot measure response time in milliseconds. This summary is only what you saw.
How to use the ghosting test
- Set your monitor to the refresh rate you play at (on Windows: Settings > System > Display > Advanced display; on a Mac: System Settings > Displays). Close other tabs and apps that could slow the browser down.
- Click Start ghosting test. Shapes start moving across black, gray and white lanes.
- Follow one shape with your eyes instead of staring at one spot. Trails and blur show only while your eyes track the motion.
- Work through the four presets: Ghosting, Overshoot, Black smearing and Motion blur. After each one, choose what you see under “What do you see?”.
- Use Full screen for bigger lanes. Press Esc or Exit to come back, and click Stop test when you are done.
Each preset switches the background to the one where its fault shows up clearly: gray for Overshoot, black for Black smearing, and all three for the other two. The Speed menu offers 240, 480, 960 and 1,920 px/s, rounded to whole screen pixels per frame. If you are not sure what you see, look again at a slower speed or in full screen.
What the results mean
The test gives two kinds of results: numbers it measures (refresh rate, dropped frames, speed) and what you report seeing.
| Result | What it means | What to do |
|---|---|---|
| Trails behind a shape (Ghosting, answer Trails) | Pixels change color too slowly, so a faint copy follows the shape. Trails grow with speed. | Raise the monitor’s overdrive one level and look again. |
| A bright or dark outline around a shape on gray (Overshoot, answer Halos) | Overdrive pushes pixels past the target shade. This is also called inverse ghosting. | Lower overdrive one level. |
| A dark smudge behind dark gray shapes on black (Black smearing, answer Smearing) | Pixels switch slowly between near-black shades. VA panels do this most often. | Try a stronger overdrive level or a little more brightness. |
| Vertical lines merge, horizontal lines stay sharp (Motion blur, answer Blurry) | Each frame stays on screen until the next one, so tracked motion blurs even on a good screen. | Use a higher refresh rate or the monitor’s blur reduction mode. |
| Refresh rate: 60, 120, 144 Hz or another value | The rate at which your browser draws new pictures on this screen. | If it is lower than your monitor’s rating, see “Refresh rate stuck at 60 Hz” below. |
| Dropped frames: 0 | The browser missed no frames, so stutter is not the cause of what you see. | Nothing to fix. |
| Dropped frames rising, with “Frames are being dropped” | The browser misses frames. That stutter is not ghosting. | Close other tabs and apps, then start the test again. |
Under the test, “Your observations” lists your answers and a verdict that comes only from them. It says “Clean so far” when you answered Clean or Sharp at least once and reported no fault, “You saw” followed by the faults you reported, or “Not sure yet” when every answer was Not sure. It never judges the screen itself.
Refresh rate reads “Measuring…” for the first moments and shows “Frame timing is unstable”, with no number, when frames arrive unevenly. A reading close to a common rate, such as 59.94 Hz, is shown as 60 Hz. Dropped frames counts frames that arrived late; the line under the number shows the last 5 seconds.
Speed is the speed after rounding to whole screen pixels per frame. On a 144 Hz screen at 100% scaling, the 960 px/s setting becomes 7 pixels per frame, which is 1,008 px/s. On a narrow window or a phone the test lowers the speed so a shape crosses a lane at most 3 times a second, and the cell says “Capped for this width”.
Motion blur follows from the refresh rate. At 960 px/s, a frame that stays on screen for 16.7 ms (60 Hz) smears a shape over about 16 pixels, and one that stays for 6.9 ms (144 Hz) over about 7 pixels. Doubling the refresh rate halves the blur.
Ghosting depends mostly on the monitor’s overdrive setting. Try every level, from off to the strongest, and test at the refresh rate you play at. Some monitors tune overdrive for their top rate and overshoot more at 60 Hz.
Ghosting test not working?
This test needs no permission, so it has one error message of its own.
Browser not supported
The test needs animation frames from the browser, which every current version of Chrome, Edge, Firefox and Safari provides. If the page says your browser does not support this test, update the browser or open the page in one of them.
Refresh rate stuck at 60 Hz
The test shows the rate your browser really draws at, which can be lower than the monitor’s rating.
- Open the display settings and pick the highest rate: Settings > System > Display > Advanced display on Windows, System Settings > Displays on a Mac.
- Some HDMI cables and ports limit the rate. Try the cable and port the monitor’s manual recommends.
- Battery saver and low power modes can lower the rate on laptops and phones. Plug in and turn them off.
- The browser draws at the rate of the monitor that holds most of the window. Move the window fully onto the fast monitor.
- Safari on iPhone limits web pages to 60 frames per second, even on 120 Hz screens.
Refresh rate will not settle
A reading needs about 1.5 seconds of frames, and the test names a rate only when most frames arrive evenly. “Frame timing is unstable” means they do not. Close other tabs and heavy apps, plug in a laptop, keep the window on one monitor, and wait a few seconds. When you move the window to another screen, the test measures again from the start.
Dropped frames and stutter
If the shapes jump or the warning appears, the browser is missing frames, and trails you see now may be stutter. Close other tabs and apps, plug in a laptop and turn off battery saver. Then click Stop test, start again and check the counter before you judge the screen.
The shapes look slow, or Speed says “Capped for this width”
The test never lets a shape jump more than half its own width in one frame or cross a lane more than 3 times a second. On a narrow window it lowers the speed to respect both. Use a wider window, full screen, or a phone held sideways.
The shapes do not move
With reduced motion turned on in your system, the test shows a message and waits for you to click Start motion. To change that setting, go to Settings > Accessibility > Visual effects > Animation effects on Windows, or System Settings > Accessibility > Display > Reduce motion on a Mac. The shapes also stop when you switch to another tab or leave the page, because nothing should move where nobody can see it. Click Start ghosting test again.
Full screen does not open
The test asks the browser for full screen. If the browser refuses, for example inside an embedded frame, or on iPhone, where Safari allows full screen only for video, the test fills the page instead. Press Esc or click Exit to return.
How we measure
The refresh rate comes from the gaps between requestAnimationFrame timestamps over the last 4 seconds, and the test shows it only when most frames arrive evenly, matching a common rate such as 60 or 144 Hz within 1% and otherwise rounding to whole hertz. A frame counts as dropped when it arrives later than 1.5 frame times after the one before. The shapes move a whole number of screen pixels per frame, so a dropped frame shows as a jump rather than slower motion. A web page cannot measure response time or see the panel itself, so the verdict comes only from your answers.
Frequently asked questions
How do I test my monitor for ghosting?
Start the test, follow one moving shape with your eyes and, for each of the four presets, choose what you see. A faint copy trailing the shape is ghosting. Then change your monitor’s overdrive setting, run the test again at the refresh rate you play at, and compare the trails.
How do I fix ghosting on my monitor?
Change the monitor’s overdrive setting. Open the monitor’s on-screen menu with the buttons on the monitor, look for Overdrive, Response Time, Trace Free or OD, often in a gaming or picture section, and change it one level at a time. Run the test again at the same speed after each change, and keep the level where neither trails nor halos show. If no level looks clean, the panel itself may be the limit. Also check that the monitor runs at the refresh rate you play at.
What is the difference between ghosting and motion blur?
Ghosting is a faint separate copy left behind a moving object, caused by pixels that change color too slowly. Motion blur is a soft edge on the object itself, because each frame stays on screen while your eyes keep moving. A screen can show both at once, and the presets let you judge them one at a time.
Can a website measure my monitor’s response time?
No. Response time in milliseconds needs a light sensor and an oscilloscope. This test measures only your refresh rate and dropped frames, and it builds its summary from what you say you saw. It tells you whether trails or halos are visible, not how many milliseconds a pixel takes to change.
Is keyboard ghosting the same as monitor ghosting?
No. Keyboard ghosting means a keyboard fails to register some keys pressed at the same time. Monitor ghosting is a trail behind moving objects on a screen. This page tests the screen only.
Is the ghosting test safe if motion bothers me?
Nothing moves until you click Start ghosting test, and a shape crosses any spot of a lane at most 3 times a second. If your device asks for reduced motion, the shapes wait for a click on Start motion and are smaller and slower. Click Stop test to end the test at any time.