Frame skipping test

How to run the test

1. Set the refresh rate you want to check, for example after overclocking the monitor with custom resolution settings. Confirm with the monitor refresh rate test that the browser runs at that rate.
2. Press Full screen.
3. Set your camera or phone to a manual or pro mode with a shutter time of 1/10 s or longer, low ISO and focus on the screen. Hold it steady or rest it on something.
4. Take several photos of the whole grid. Watch Late frames while you do it.

Reading the photo

• A continuous run of lit cells: no frame was skipped during that exposure. The run is roughly as long as the shutter time multiplied by the refresh rate — about 14 cells for 1/10 s at 144 Hz.
• An unlit cell inside the run: that frame was drawn but not shown, which is what frame skipping looks like. If it happens in every photo, lower the refresh rate step by step until it stops.
• One cell clearly brighter than its neighbours: that frame stayed on screen for two refreshes, usually because the browser was late, not the monitor. The Late frames count will usually rise at the same time.
• Dimmer cells at the start and end of the run are normal: the exposure began or ended partway through those frames.

Keep the exposure short enough that the run does not wrap all the way round the 60 cells — at 144 Hz, under about 0.4 s.

Limits

• The page can only show frames the browser draws. If the browser itself drops frames, the photo cannot separate that from the display; repeat the test with fewer apps open.
• Each photo covers a fraction of a second. Skipping that comes and goes can be missed, so take several.
• Phone cameras with rolling shutters may record the top and bottom of the screen at slightly different times, which can make the run look uneven between rows.
• The page does not detect skipped frames automatically: you judge them from the photo.

For motion clarity and overdrive, use the monitor ghosting test.