How the test works
Press Start and the screen fills with the chosen background. A tile with vertical stripes of growing width, from one pixel to eight, sits still in the upper half as the reference. A second, identical tile crosses the lower half from left to right at the chosen speed and wraps around. Your job is to follow the moving tile with your eyes, the way you follow a car passing by, and compare its stripes to the still copy.
The speeds are 240, 480, 960 and 1920 pixels per second. Tap the screen, press Space or the right arrow to go to the next speed, the left arrow to go back. The caption at the bottom shows the speed, how many pixels the tile moves between frames at the frame rate the browser is delivering, and the time. The background can be dark, grey or light, because blur and ghosting look different on each: dark backgrounds show overshoot halos, light ones show dark smears.
While the tile moves, the test counts the frames the browser draws, the same measurement as the refresh rate test. Press Esc, swipe down or use the exit button to finish. The result card records how long you watched, the last speed, the pixels per frame, the background and the frames skipped, so a screenshot of the card is a complete note of the conditions.
Under reduced motion the tile stands still and moves for three seconds each time you tap; the left arrow changes the speed.
What the result means
The browser cannot see the panel, so the result is a record of what was shown, not a grade. The judgement is yours, and it goes like this:
- All stripes sharp at every speed. A fast panel, typically 120 Hz or more with good overdrive, or an OLED. Nothing to do.
- Thin stripes blur at 960 and above, sharp below. Normal for a 60 Hz LCD. At 60 Hz the tile moves 16 pixels per frame at 960 pixels per second, and the one and two pixel stripes cannot survive that.
- A bright or dark halo just outside the tile. Overshoot from too much overdrive. Lower the setting in the monitor menu.
- A faint copy trailing behind the tile. Ghosting, from pixels that change too slowly. Raise overdrive by one step, or accept it: on VA panels a dark background shows it most.
- The tile jumps or stutters. Skipped frames; look at the count on the card and at the fps test. Not a panel fault.
- Blur much worse on one side of the screen. Uneven panel response, which is a fault.
Pixels per frame is the useful number to compare between screens: at the same speed, a 144 Hz panel moves the tile 6.7 pixels per frame and a 60 Hz panel 16, and the blur scales with it.
What to do about blur and ghosting
Open the monitor menu and find the overdrive or response time setting, often called OD, Trace Free, Response Time or AMA. Run the test at 960 pixels per second and step through the levels: ghosting means the level is too low, a halo means too high. Set the refresh rate to the highest the screen supports, since that reduces blur more than any other setting. On a TV, game mode turns off processing that adds lag, and motion smoothing or black frame insertion reduces blur at the cost of a dimmer picture and, sometimes, flicker. On a phone, the adaptive or high refresh setting does the same job. If the picture is fine at 60 Hz and smears at 144, the cable or the overdrive at that rate is the cause; try a DisplayPort cable.
When to return or claim the warranty
Motion blur within the normal range for the panel type is not a defect and is not a warranty matter, and shops know the difference. What is covered: ghosting or smearing that is clearly worse on one part of the screen, a coloured trail behind moving objects at every overdrive setting, or a panel that cannot reach its advertised response without heavy overshoot. Before contacting the seller, note the monitor's model, the overdrive level, the refresh rate shown by the refresh rate test and the speed at which the fault appears, and photograph the trailing halo with a short exposure if your camera allows it. A new monitor can be returned within the return window simply because its motion handling is not what you expected; after that window, the fault has to be one of the above.
Frequently asked questions
How do I read the test?
Look at the moving tile, not at a fixed point. Its stripes should look as sharp as the stripes of the still tile above. If the thin stripes melt together while the thick ones stay, the panel has motion blur. A darker or brighter copy trailing behind the tile is ghosting or overshoot. Try each speed; blur that only appears at the fastest speed is normal for most monitors.
Is motion blur a defect?
Usually not. Every sample-and-hold display, which is every LCD and OLED, blurs moving objects because the picture stays still for a whole frame while your eye keeps moving. A higher refresh rate shortens that hold and reduces the blur, which is the main reason 120 and 144 Hz screens look smoother. A defect is a coloured trail, a smear that lags well behind the tile, or blur that is much worse on one side of the screen.
What does the overdrive setting on my monitor do?
It pushes pixels harder so they change colour faster, which reduces the smear. Too much of it causes overshoot: a bright or dark halo just ahead of or behind the tile. Run this test while changing the overdrive setting in the monitor menu and pick the level where the halo disappears; the middle setting is usually right.
Why does the tile stutter instead of blur?
Stutter is missing frames, not a slow panel. The result card lists the frames the browser skipped during the run; if there are many, the machine could not keep up with the refresh rate, and the same tile would look smooth on a faster computer. The fps test isolates that.
Does the test work on a phone or TV?
Yes, in any browser. On a phone, hold it in landscape so the tile has room to move. On a TV, open the page in the TV's own browser or cast it, and try the motion smoothing or game mode settings while watching; the difference between them is easy to see here.