What stutter and tearing look like. Drawn on purpose, not measured.
When motion looks bad it helps to know which fault it is, because each has a different cause. This draws each on purpose: smooth, what microstutter looks like, what stutter looks like, the halving that vertical sync does, and what tearing looks like. It gives no verdict; the frame pacing test is the one that measures.
This check is visual: it draws movement or flicker on the screen, and you judge the result by eye, so a screen reader cannot describe it. The list under "What it measures" says in words what each one shows. If motion or flicker makes you unwell, or you have reduced motion switched on, you can leave it out: no other test on this site depends on it.
One check
- Stutter and tearing
One check after another, with your progress along the top and a plain verdict on each. Nothing you show the camera or say into the microphone leaves this page.
In short
Stutter and tearing demo: the answer first
A stutter and tearing test draws each motion fault on purpose, smooth, microstutter, stutter, vertical sync halving and tearing, so you can match what you see in a game to its name and its fix. It is a reference; the frame pacing test is the measurement.
Reading your result
- Tearing
- Two frames on screen split across a line. Variable refresh rate with a frame cap just under the refresh rate removes it.
- Halving
- Vertical sync without variable refresh drops to half rate when a frame is late. Variable refresh or a frame cap the machine can hold fixes it.
- Stutter
- Irregular holds, usually something busy in the background. Measure it with the frame pacing test.
What it measures
Measured here, not assumed.
- What microstutter looks like
- One frame in eight lands a step short. Barely visible, felt as a roughness; in a game, usually two frames delivered too close together.
- What stutter and halving look like
- The mark holds for three frames then jumps, or every frame is shown twice. Regular holds like these are strictly judder; real stutter is irregular, which is why the pacing test measures and this only shows.
- What tearing looks like
- Two frames on screen at once, split across a line. A browser cannot tear a composited canvas, so this is a drawing of tearing with the top half newer than the bottom.
If it fails
The usual failures, and what fixes each.
- Your game tears
- Turn on vertical sync, or better, variable refresh rate (G-Sync, FreeSync) if the monitor has it, with the frame rate capped just under the refresh rate.
- Your game halves
- Vertical sync without variable refresh drops to half rate when a frame is late. Use variable refresh, or a frame cap the machine can hold.
- Your game stutters
- Look for what is busy: a background program, a full drive, a driver. The frame pacing test shows whether the machine can deliver even frames at all.
Where a browser stops
What it cannot tell you.
- Everything here is drawn, nothing is measured, and the result is recorded as a demonstration rather than a verdict. The frame pacing test measures what your machine actually delivers.
- A game's stutter has causes a page cannot see: shader compilation, loading, a background process. The pictures help you name it; the fix is in the game or the system.
- Variable refresh rate removes tearing and halving; this shows what they look like without it.
Privacy
Nothing leaves this page.
The camera and microphone are read on this page and stopped as soon as they have been measured. The clip you can play back lives in the browser's memory and is discarded when you leave. The location check discards the position. The internet test sends random bytes to this site and nothing else. The result is stored nowhere unless you ask for it by email, and then only the fact that an email was sent is kept.
Questions
Stutter and tearing demo, answered
- What is the difference between stutter and tearing?
- Stutter is time: frames arrive unevenly, so motion jumps. Tearing is space: two frames share the screen, split by a line. The demonstration shows each.
- What is microstutter?
- Small, frequent unevenness in frame delivery, often two frames bunched together. It looks like a roughness rather than a jump, and it is common with multiple graphics cards or badly paced frame caps.
- Does variable refresh rate fix stutter?
- It fixes the halving and the tearing, because the screen waits for each frame. It cannot fix frames that are late; that is the machine, and the frame pacing test shows it.
- Why does the page draw tearing instead of causing it?
- A browser composites its canvas, so it cannot tear. The drawing shows what tearing looks like, with the top half newer than the bottom.
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