Monitor Ghosting Test
A UFO-style moving object test for ghosting, overdrive overshoot and motion blur. Track the object with your eyes and compare the trail on dark, mid and light backgrounds.
UFO motion test
Measuring paint rate…
What to look for behind the object
The object keeps the speed you pick, in pixels per second. Each frame moves by that speed divided by the refresh rate, and only whole device pixels are drawn, so a fraction waits for the next frame. Actual speed, above, is the rate those frames really covered. It matches the button while motion is smooth, and it falls if a frame is late, because the object does not jump ahead to catch up. This page cannot time how fast a pixel changes colour. Look for a fading smear, a bright or dark halo, and soft blur. Keep this tab visible. If you leave, motion pauses so the object does not jump when you come back. Close heavy tabs and use full screen for the cleanest motion. A photo of the UFO freezes one frame and adds camera blur, so it is not the trail you see while tracking with your eyes.
Why the box says 1 ms
How the test works
The page times the gap between animation frames and uses the median as the paint rate. It is not the refresh setting in Windows or macOS, and a browser can paint near 60 Hz on a faster panel. Each frame adds the speed you picked divided by that rate, keeps any fraction, and draws only whole device pixels. The average matches the button: at 960 px/s and 60 Hz that is 16 px per frame, and at 144 Hz the step averages about 6.7 px. A late frame does not fling the object forward. Follow the object with your eyes, like a pursuit camera following a car, and use the static centre line and ticks to check you are tracking it, not staring at one spot. The trail you see is what the panel adds. If you leave this tab, the animation frame is cancelled and the object stays where it is. If the dropped-frame counter climbs, the motion stutters and the result means nothing; check the rate with the refresh rate test.
Ghosting, inverse ghosting and motion blur
Ghosting is a smeared tail behind the object: the pixels cannot finish changing before the next frame, and on VA panels it is often worst on the dark lane. Inverse ghosting is a bright or dark halo in the opposite colour, caused by overdrive pushing pixels past their target. Even a perfect panel shows some even blur, because each frame is held on screen for the whole refresh while your eyes keep moving. That is sample-and-hold blur, and only more Hz or strobing reduces it.
Tuning overdrive
Overdrive goes by names like Response Time, OD, TraceFree or AMA. Start at the middle setting, run the test at 960 px/s, then step up until the smear shortens and stop as soon as halos appear. Check all three lanes, since a setting that is clean on mid grey can overshoot on the dark one, and recheck at a lower refresh rate if you use variable refresh.
The 1 ms claim, strobing and OLED
The response time on the box is usually a best-case grey-to-grey figure, taken at the harshest overdrive mode, the one that tends to overshoot. This page cannot turn that into a millisecond reading. Watch the trail: a fading smear means the pixels are slow, a bright or dark halo means overdrive is too high, and even softness on both edges is sample-and-hold blur. Backlight strobing (ULMB, ELMB, DyAc) flashes the backlight once per frame and cuts that blur sharply, at the cost of brightness and some flicker. OLED panels usually show no smear or overshoot, but they still hold each frame, so the sample-and-hold blur remains. That is why 240 Hz looks clearer than 144 Hz: each frame is held for about 4.2 ms instead of 6.9 ms, so that blur is about 40% shorter.
Related tools
- Refresh Rate Test: confirm the monitor runs at the rate you paid for.
- Frame Skipping Test: check that an overclocked panel shows every frame.
- FPS Test: compare how 30, 60 and higher frame rates look side by side.
- Display Test: run a full set of screen checks in one place.
Frequently asked questions
What is the difference between ghosting and overshoot?
Ghosting is a fading smear behind the object: the pixels have not finished changing colour before the next frame. Overshoot, also called inverse ghosting, is a bright or dark halo in the opposite colour. It appears when overdrive pushes the pixels past the colour they should land on. Compare those trails by eye on the dark, mid and light lanes.
Why does a photo of the UFO lie?
A phone photo freezes one moment, and the camera shutter plus any handshake adds its own blur. The smear, halo and blur that matter show up while your eyes follow the object. Track it and use the still centre line to see that you are following, not staring at one spot. A still photo cannot show that pursuit trail.
Does this measure grey-to-grey response time?
No. A lab grey-to-grey figure needs a photodiode and a controlled pattern. This page cannot print a response time in milliseconds. It moves an object so you can see smear, a bright or dark halo, and blur. The millisecond number on the box is a marketing spec, usually taken at the harshest overdrive mode.
Does the tab have to stay visible?
Yes. Browsers slow or stop animation frames when a tab is in the background. This page cancels the animation while the tab is hidden and does not add the missed time, so the object does not jump when you come back. Leave the tab in front, and close heavy pages so the motion stays even.
Why might the actual speed differ from the button I picked?
While frames arrive on time, the average matches 480, 960 or 1920 px/s. Any fraction of a pixel is carried to the next frame, and only whole device pixels are drawn. Actual speed is measured from the pixels just drawn. It falls if a frame is late, because that frame does not fling the object forward to catch up.
How do I set overdrive from what I see?
Start at the middle setting. It may be named Response Time, OD, TraceFree or AMA. Run the test at 960 px/s and watch all three lanes. Raise the setting until the smear shortens, and lower it as soon as a bright or dark halo appears. Check again at a lower refresh rate if you use variable refresh, because a clean setting at a high rate can overshoot when the rate drops.
What is the soft blur that is not a one-sided trail?
Even softness on both edges is sample-and-hold blur. The panel holds each frame for the whole refresh while your eyes keep moving. More hertz, or a backlight strobe mode, shortens that blur. It is not the same as a one-sided smear from slow pixels or a halo from too much overdrive.