Frame Skipping Test
The Frame Skipping Test advances a numbered marker one step every animation frame and logs the gap between frames, so you can watch the Frames Rendered and Dropped (Browser-Side) counters while it runs. Click Start and let it run for a bit — your browser can only catch drops happening on its own side, so if the counter looks clean but playback still feels stuttery, the camera long-exposure method is the way to confirm whether the panel itself is skipping frames. Use the flicker test online to confirm whether your monitor shows this issue before you adjust settings or return it.
Frame Skipping Test
Click Start and watch the counter and moving marker below — each tick should advance by exactly one frame. If the counter reports zero dropped frames but the panel still looks stuttery, dropped panel frames need the camera long-exposure method (photograph the moving marker with a shutter speed slower than one frame) to confirm the display itself is the cause, not your browser.
This test advances a marker by one step on every requestAnimationFrame callback and times the gap between callbacks. If a gap comes in noticeably longer than the running average, the browser counts it as a dropped frame. It's a real, useful signal — but it only sees what's happening on your browser's side of the pipeline, which is a narrower question than "is my monitor skipping frames."
What This Test Can and Can't Detect
A frame counted as "dropped" here means the browser itself failed to get a new frame to the screen on schedule — usually because the main thread was busy with something else (a background tab, a heavy script, garbage collection) and missed its window to paint. That's a real cause of visible stutter, and it's the kind of drop this counter is built to catch. Use the run a convergence test to confirm whether your monitor shows this issue before you adjust settings or return it.
What it can't see is frame handling that happens after the browser has already handed a frame off — inside the display's own scaler, or in the cable link between your GPU and the panel. If the counter reports zero dropped frames but motion still looks stuttery, the problem is downstream of the browser, and the only reliable way to confirm it is a camera long-exposure photograph of the moving marker: point a phone camera at the screen with a shutter speed slower than one frame interval and look at whether the streaks are evenly spaced.
Why a Clean Counter Doesn't Guarantee Smooth Motion
Several things can cause visible stutter even when this test reports a perfect frame count: The free black level test is free and runs entirely client-side, so nothing about your display is ever uploaded.
- Panel-side frame rate conversion. If the video signal's frame rate doesn't divide evenly into your display's refresh rate, the panel's own scaler has to repeat or insert frames to make up the difference — for example, a 60fps source on a 144Hz panel needs a frame repeated periodically because 144 isn't a clean multiple of 60. The browser sent every frame on time; the panel is the one reconciling the mismatch.
- Cable or port bandwidth. An older HDMI cable or port can run short of bandwidth at high resolution-and-refresh-rate combinations, causing the display to silently fall back or drop frames at the hardware level, invisible to anything running in the browser.
- Adaptive sync range limits. G-Sync and FreeSync match the panel's refresh rate to the GPU's output, but only within a supported range — outside it, the display falls back to a fixed rate and may duplicate frames, again below what the browser can observe.
Reading the Counters
Frames Rendered is a simple running count since you pressed Start. Dropped (Browser-Side) increments any time the gap between two consecutive animation frames comes in more than 1.5× the recent average gap — a threshold loose enough to ignore normal jitter but tight enough to catch a genuinely missed frame. Measured Refresh is an estimate derived from that same average gap, so it should settle close to your display's actual refresh rate after a few seconds of running.
If Dropped (Browser-Side) climbs steadily while this tab is the only thing open, close other tabs and background applications first — heavy CPU or GPU load elsewhere on the system is the most common cause of browser-side drops, and it's worth ruling out before assuming anything is wrong with your display itself.
Confirming Panel-Level Skipping With the Camera Method
Because this counter can't see past the browser, the camera long-exposure method is the practical way to check what the panel is actually doing. Set a phone camera to a shutter speed slower than one refresh interval (for a 60Hz display, slower than roughly 1/60s), aim it at the moving marker while the test runs, and take a shot. Evenly spaced streaks mean the panel is presenting frames at a consistent cadence; an uneven gap or a doubled-up streak points to the panel itself repeating or dropping frames — a hardware-level issue this browser-side counter has no way to catch.
Frequently Asked Questions
- What is frame skipping on a monitor?
- Frame skipping occurs when your display repeats a previously shown frame instead of rendering the next new one. This results in stuttering or uneven motion, particularly noticeable during fast-paced games or animations. It can be caused by signal integrity issues on the cable, GPU rendering delays, or monitor timing inconsistencies.
- Why does this test show zero dropped frames but motion still looks stuttery?
- This counter can only see drops that happen on the browser's side — a missed requestAnimationFrame callback. It has no visibility into frame handling inside your display's own scaler or the cable link to it. If the counter is clean but motion still stutters, use the camera long-exposure method described above to check whether the panel itself is the cause.
- Does V-Sync prevent frame skipping?
- V-Sync reduces screen tearing by synchronizing frame delivery to the refresh rate, but it can introduce input lag and does not fully eliminate skipped frames. Adaptive sync technologies like G-Sync or FreeSync are more effective, dynamically adjusting the refresh rate to match GPU output and reducing both tearing and frame skips.
- Is frame skipping the same as screen tearing?
- No. Screen tearing happens when two frames are displayed simultaneously in one refresh cycle, creating a visible horizontal split. Frame skipping is when a frame is never shown at all — the monitor displays the same frame twice in a row. Both degrade visual smoothness but have different causes and solutions.
- Why would a 60fps source cause judder on a 144Hz display?
- 144 isn't a clean multiple of 60, so the display's scaler can't map every source frame to an equal number of refresh cycles. It ends up holding some frames for a slightly different duration than others to make the ratio work out, and that irregularity is perceived as judder even though the source itself is delivering a perfectly steady 60fps.
- Can background applications affect this test's results?
- Yes. Anything competing for CPU or GPU time — another browser tab playing video, a heavy background process, even browser extensions — can delay the main thread long enough to miss an animation frame's paint window. Closing other tabs and applications before running the test gives a cleaner read on your display's own behavior.