Frame Skipping Test

Photograph a fast numbered sequence to find out whether your monitor shows every frame at its current refresh rate.

Go to test controls

This check opens a focused test surface. You can return with Escape. How accurate is this test?

Before you start

  • Keep this tab visible and close heavy background work while the pattern settles.
  • Use a supported manual shutter setting from the READY exposure guide; full-cycle or wrapped photographs cannot support this comparison.
Step-by-step instructions

How to run this check

  1. Open the Frame Skipping Test and leave the numbered pattern running automatically
  2. Enter fullscreen and wait until the pattern state changes from WAIT to READY
  3. Use the displayed browser-cadence guide to choose a manual shutter spanning about 4–12 of the 24 positions
  4. Take several photographs and discard full-cycle, wrapped, clipped, or unstable captures
  5. Look for gaps in the numbered trail; an evenly spaced trail means every frame was shown, a repeated gap means frames are being skipped

Long-exposure camera pattern

Photograph the numbered sequence

The pattern is already running. Enter fullscreen, wait for READY, then use the exposure guide below to photograph a short trail with a steady camera.

WAIT
Browser cadence —
Timing stability —
Pattern state WAIT
24-frame sequence WAIT

One cell advances on each browser animation callback

Wait for READY to see exposure guidance based on this browser sequence.

Calibrating browser timing. No camera access or upload is used.

Camera setup

A screenshot captures one instant and cannot show this sequence. Use a real camera exposure that spans several refreshes.

  1. 1. Set the exposure

    Choose a manual exposure spanning roughly 4–12 positions using the current browser-cadence guide. An exposure covering the whole 24-position cycle can hide missing positions.

  2. 2. Separate the cells

    Lower ISO, exposure, or display brightness if the trail becomes one white smear.

  3. 3. Repeat the photo

    Take at least three steady photographs. Keep captures with one short trail away from the 24 → 1 boundary; discard wrapped, full-cycle, clipped, or unstable captures.

This sequence advances once per animation callback and repeats after 24 positions. At 60 browser FPS a cycle is about 400 ms, so 1/10 s covers about six positions. At 240 browser FPS a cycle is about 100 ms: 1/10 s covers the whole cycle and is unsuitable. A 1/30 s exposure covers about eight positions instead. These are pattern-framing calculations, not measurements of panel refresh or camera timing.

Choose a shutter setting your camera actually supports within the displayed range. If only automatic exposure is available, or the photo fills or wraps the sequence, leave the result unassessed. Save the original photos with shutter, browser cadence, configured OS rate, and display connection in their filenames or your notes.

Typical capture

A continuous numbered run

123456789101112

Illustration only: one short trail with consecutive positions, away from the sequence boundary. Dark cells outside the trail and partially lit end cells are expected exposure boundaries, not missing frames.

Recheck this pattern

Internal gaps repeat

1 2 3 4 5 6 7 8 9 10 11 12

Illustration only: a dark position inside an otherwise continuous short trail. Look for internal gaps across several usable photos; they need not occur at the same numbered position. One odd photo cannot establish a fault.

Background

Why monitors skip frames

Frame skipping means the monitor accepts a signal at one refresh rate but does not show every frame it receives. The OS reports 75 Hz, for example, but the panel is only displaying 60 of those frames and silently dropping the rest. Motion then looks less smooth than the setting suggests, often with an irregular stutter.

When it happens

The most common cause is monitor overclocking: creating a custom refresh rate above the rated one with the graphics driver (NVIDIA Control Panel or AMD Software custom resolutions) or a tool such as Custom Resolution Utility. Some monitor controllers (scalers) accept the faster signal and show a picture, but internally keep refreshing the panel at its native rate and discard the extra frames.

It can also happen with some TVs and budget monitors at refresh rates that are listed but not native to the panel, and occasionally with adapters or capture devices that convert between rates.

How the photo shows it

The test lights one box per frame along a numbered row. A camera with an exposure longer than a few frames captures several consecutive boxes in one photo. If every frame reaches the screen, the lit boxes form a continuous, evenly spaced trail. If the monitor drops frames, the trail has gaps, often in a repeating pattern, because the same frames in each cycle are discarded.

Phone cameras usually need a manual or pro mode to set a slower shutter speed. Hold the camera steady or rest it on something, and take several photos: a single photo can have its own artifacts.

What to do if you find gaps

  • Go back to the monitor’s rated refresh rate. An overclock that skips frames gives you no benefit and can look worse than the native rate.
  • Try lower custom rates in small steps. Some panels handle a modest overclock cleanly and skip only beyond a certain point.
  • Swap the cable or try another port to rule out a link that drops to a lower mode.
  • Retest after driver updates. Driver changes can affect custom resolutions.

Common questions

Can frame skipping damage my monitor?
Skipping itself is the monitor ignoring frames it cannot show. Running a panel above its rated refresh rate with custom resolutions is still at your own risk, so check the monitor’s warranty terms before overclocking.
Does the test need a specific browser?
The browser must render one frame per refresh, so use a desktop browser that is not in a power-saving mode, keep the tab visible, and close heavy background apps.
Who came up with this method?
Photographing a frame sequence to spot dropped frames was popularized by Blur Busters’ TestUFO tests and is widely used by monitor overclocking communities.

How accurate is this test?

What it shows reliably

  • Whether usable photographs of a short numbered trail show repeated internal gaps while browser animation timing is stable.

What needs a measuring instrument

  • Isolating which link (cable, GPU, compositor, or monitor) skips frames takes swapping one component at a time and repeating the photo.

Reading your result

  • One 24-position cycle lasts about 24 divided by observed browser FPS seconds. At 240 browser FPS, 1/10 second covers the whole cycle and can conceal gaps; the exposure guide is browser-pattern framing, not hardware timing measurement.
  • Compare internal gaps in short unwrapped trails across several photos; they need not occupy the same number. Dark cells outside the trail and partially lit endpoints are exposure boundaries.
  • Rolling shutter, exposure settings, camera processing, browser scheduling, and operating-system composition can create misleading results.
Recommended setup and sources

Recommended setup

  1. Keep the tab visible, enter fullscreen, wait for READY, and steady the camera square to the display.
  2. Choose a supported manual shutter from the displayed 4–12-position exposure guide. Keep the setup fixed and take several photographs; discard clipped, unstable, wrapped, or full-cycle captures.

Sources

Methodology reviewed: