Frame Skipping Test
When you overclock a monitor to a higher refresh rate, it may accept the signal but silently drop frames, so it feels no smoother. This test lights the next box on every frame. Take a photo with a shutter slower than a few frames: an unbroken run of lit boxes means every frame was shown; a gap means the monitor skipped one.
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Shutter speed helper
Reading your photo
Continuous run: every frame was shown. No skipping at this refresh rate.
Dark box inside the run: the monitor skipped a frame. Lower the overclock.
One brighter box: the computer showed a frame twice (browser or GPU stall), not the monitor. Retake the photo.
How to use the Frame Skipping Test
- Set the refresh rate you want to test in your operating system (for example a custom 75 Hz or 165 Hz overclock) and open this page in a browser with hardware acceleration.
- Check the measured refresh rate below the grid. It should match the rate you set; if it does not, the browser is running at a different rate.
- Press Start full screen, close other busy apps, and set your camera or phone to manual (pro) mode with a shutter of about 1/10 to 1/30 second.
- Take a few photos of the grid, holding the camera steady.
- Read the photo: lit boxes should form one continuous run. A dark box inside the run means a skipped frame; a box brighter than the others means the computer showed that frame twice.
How the test works
The page asks the browser for a callback before every screen refresh (requestAnimationFrame) and lights the next box each time, so box 1 is lit for one refresh, box 2 for the next, and so on. A camera exposure that lasts several refreshes records all the boxes that were lit during it. If the monitor really shows every frame it receives, the photo shows an unbroken run. If it drops some frames to keep up with an overclocked signal, the boxes for those frames never appear and leave gaps, often in a regular pattern, for example every fourth box missing when a 60 Hz panel is driven at 80 Hz.
Boxes lit per photo
Expected boxes = refresh rate × exposure time. The ends of the run can be dimmer because the shutter may open or close partway through a frame.
| Refresh rate | 1/60 s | 1/30 s | 1/15 s | 1/10 s | 1/4 s |
|---|---|---|---|---|---|
| 60 Hz | 1 | 2 | 4 | 6 | 15 |
| 75 Hz | 1.25 | 2.5 | 5 | 7.5 | 18.75 |
| 120 Hz | 2 | 4 | 8 | 12 | 30 |
| 144 Hz | 2.4 | 4.8 | 9.6 | 14.4 | 36 |
| 165 Hz | 2.75 | 5.5 | 11 | 16.5 | 41.25 |
| 240 Hz | 4 | 8 | 16 | 24 | 60 |
Tips for a clean result
- Use the camera's manual or pro mode; automatic modes pick fast shutters in bright light. Lower ISO or the screen brightness if the boxes are overexposed.
- Hold the phone steady or rest it on something. Motion blur smears boxes but does not create gaps.
- Avoid a camera whose sensor reads out line by line too slowly at very fast shutters; 1/10 to 1/30 second avoids rolling-shutter confusion.
- Take several photos. One doubled box from a browser hiccup is normal; gaps that repeat in every photo are frame skipping.
- If the measured refresh rate is not what you set, check that the monitor is the one the window is on, that variable refresh (G-SYNC or FreeSync) is not lowering the rate, and that the browser's power saving is not capping it.
Frequently asked questions
What is frame skipping?
Frame skipping happens when a monitor is driven at a refresh rate above what its electronics truly support, which is common with overclocking. The monitor accepts the higher rate but drops some frames and shows the rest at its real rate. The refresh rate shown in Windows or macOS looks correct, but motion is no smoother, and can even stutter.
Why do I need a camera?
Frames are skipped inside the monitor, after the computer has sent them, so no software, including this page, can detect them on its own. A camera with a slow shutter captures several frames in one photo, and the lit boxes reveal which frames actually appeared on the screen.
Which shutter speed should I use?
Use an exposure that covers several frames but less than the whole grid. At 60 Hz, 1/10 second shows about 6 boxes; at 144 Hz, 1/30 second shows about 5 and 1/10 second about 14. The shutter helper on this page calculates it for your measured refresh rate and grid size. Phone cameras in pro or manual mode work well.
What do gaps and bright boxes mean?
Every box is lit for exactly one refresh. If the monitor skips a frame, its box never appears, so the photo shows a dark box inside the lit run. If the computer or browser misses a frame, the previous image stays on screen for two refreshes, so that box appears brighter (double exposure) and there is no gap. Bright boxes point to a software or GPU stall, gaps point to the monitor.
The page says some frames were dropped. Is my monitor skipping?
No. The drop counter only measures frames the browser itself missed, for example during page loading or when the computer is busy. Those show as doubled boxes. Monitor frame skipping can only be seen in a photo. A few browser drops while starting or switching tabs are normal.
Is monitor overclocking safe?
Small overclocks such as 60 to 75 Hz are commonly done and usually reversible by returning to the default refresh rate, but they run the panel outside its specification and may affect warranty. Increase the rate in small steps, test for frame skipping and artifacts at each step, and go back to the last good setting if you see problems.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.