Frame skipping test. Squares, and a photograph.
An overclocked monitor can accept a refresh rate it cannot show, and quietly drop frames. A web page cannot see that, because the graphics card paces the frames and a panel that drops one says nothing back. So the browser's side is counted here, and the panel's side is read from a photograph.
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
- Frame skipping
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
Frame skipping test: the answer first
A frame skipping test catches a monitor that accepts a refresh rate it cannot show. The page counts the frames the browser missed, then lights a strip of squares one per frame for you to photograph; a gap in the photographed run is a refresh the panel skipped.
Reading your result
- Clean browser side first
- If the browser missed frames, the photograph cannot be read. Close other programs and run again.
- A gap in the run
- The panel is skipping at this rate. Lower an overclock a step at a time until the photograph is clean.
- One square per photo
- The shutter is too fast. Use a slow shutter or a long exposure mode so several frames land in one picture.
What it measures
Measured here, not assumed.
- Frames the browser missed
- Counted from the timing of frames. The browser's side must be clean before a photograph means anything.
- The strip
- One square per hertz of the measured rate, lit one per frame for ten seconds, in rows so a whole refresh cycle is on screen at once and never wraps.
- The photograph
- A tenth-second exposure or longer. Lit squares in a run with no gap: the panel skipped nothing. A gap: a skipped refresh.
If it fails
The usual failures, and what fixes each.
- Gaps in the photograph
- The panel is skipping refreshes at this rate. Lower the overclock a step at a time until a photograph shows a clean run.
- The browser missed frames
- Close other tabs and programs and run it again. The photograph can only be read once the browser's side is clean.
- Every photo shows one square
- The shutter is too fast. Use a slow shutter or a long-exposure mode so several frames land in one photo.
Where a browser stops
What it cannot tell you.
- The panel's own skipping is invisible to a page. Only the photograph can show it, which is why the test asks for one.
- A phone camera at a fast shutter shows one square; set a slow shutter, a night mode, or a long exposure.
- Screenshots cannot show it either: a screenshot is one frame.
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
Frame skipping test, answered
- How do I test an overclocked monitor for frame skipping?
- Run the test, photograph the strip with a tenth-second exposure or longer, and look for gaps in the run of lit squares. A gap is a skipped refresh; a clean run means the panel is keeping up.
- Why can a website not detect frame skipping itself?
- Because the graphics card sends every frame and a panel that drops one does not report it. The browser only sees its own missed frames, which this test counts and reports separately.
- What exposure should the photo use?
- A tenth of a second or longer. At 144 Hz that captures about fourteen frames, enough to see a gap. Phones do this in a night mode or a manual mode.
- Why can't the page detect skipping on its own?
- The graphics card paces the frames, and a panel that drops one sends nothing back. Only a camera looking at the screen can see it.
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