Screen Tearing Test
Watch fast moving bars to spot screen tearing: a horizontal break where the top and bottom of each bar no longer line up. Adjust speed and bar width, go full screen and read the live frame rate, refresh rate and dropped frames.
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Keys: Space pause, ← → speed, ↑ ↓ bar width, F full screen. Tearing shows as a horizontal break where the top and bottom parts of a bar don't line up.
How to use the Screen Tearing Test
- Watch the moving bars: the test starts at once at 1,440 pixels per second.
- Press Start full screen for the most reliable view, and look at the middle of the screen rather than following one bar.
- Look for a horizontal break where the bars shift sideways. A tear line that jumps around or crawls up the screen is classic V-Sync off tearing.
- Change speed and bar width with the sliders or arrow keys: wider bars and higher speeds make tears larger.
- Check the stats: frame rate should match your refresh rate, and dropped frames should stay near zero. Copy the result to share it.
Tearing, judder or blur: what you are seeing
| What you see | Likely cause | What to try |
|---|---|---|
| A horizontal break with the lower part of the bars shifted sideways | Tearing: a new frame was shown in the middle of a refresh (no V-Sync) | Enable a compositor or V-Sync, G-SYNC or FreeSync; update the GPU driver |
| Several break lines at once | Frame rate far above the refresh rate with V-Sync off | Limit the frame rate or turn on V-Sync |
| Bars jump unevenly but stay straight | Judder or stutter from dropped or late frames | Check the dropped frames counter, close heavy apps, plug in a laptop |
| Bars leave a faint trail or halo | Pixel response time (ghosting or overshoot), not tearing | Adjust the monitor overdrive setting |
| Bars look doubled or duplicated | Frame interpolation or strobing on a TV or monitor, or your eyes tracking motion at low refresh rates | Use game mode on TVs; compare at a lower speed |
How the test works
The pattern is redrawn on every display refresh with requestAnimationFrame, at the screen's native resolution. The distance the bars move per frame is speed ÷ refresh rate, so 1,440 px/s on a 60 Hz screen moves 24 pixels each refresh, and 10 pixels on a 144 Hz screen. A tear shifts the lower part of each bar by about that many pixels, which is why higher speeds make tearing easier to see.
The refresh rate is the median of the last 240 frame intervals (1000 ÷ median ms). A frame counts as dropped when its interval is more than 1.5 times the median, and long gaps add one dropped frame per missed refresh.
Tips for testing V-Sync and adaptive sync
- Use full screen and look at the middle of the screen. Tears are easiest to spot with wide bars and a white on black pattern.
- Try the Opposite rows pattern: rows moving in different directions make a tear line show as a step across every row.
- To check G-SYNC or FreeSync, enable the monitor's on-screen refresh rate counter; in a browser it should match the refresh rate shown here.
- Games run outside the browser compositor, so if games tear but this page doesn't, change V-Sync or frame limit settings in the game or GPU control panel.
Frequently asked questions
What does screen tearing look like?
Tearing shows one frame on the top part of the screen and the next frame on the bottom part, so moving vertical bars appear cut by a horizontal line with the lower part shifted sideways. The line often moves or flickers from frame to frame. Stutter or judder is different: the whole image jumps unevenly but stays in one piece.
Why does tearing happen?
It happens when the graphics card replaces the image being sent to the monitor in the middle of a refresh. That is the normal behavior with V-Sync turned off when the frame rate does not match the refresh rate. V-Sync, G-SYNC, FreeSync and other adaptive sync technologies prevent it by timing frame changes with the display.
Can a web page show tearing at all?
Browsers normally draw through the operating system's compositor, which waits for vertical sync, so on most Windows, macOS, Android and iOS setups this test shows no tearing. Tearing in a browser points to the display pipeline: Linux X11 sessions without a compositor or with TearFree disabled, some GPU driver settings, remote desktops and screen capture tools, or a monitor or TV processing the signal badly.
What is the Whole pixels per frame option?
Normally bars move by a distance based on elapsed time, which can be a fraction of a pixel. With this option on they move by the same whole number of pixels on every refresh, so any uneven jump you see is caused by dropped or late frames rather than by rounding.
Why is my frame rate lower than my refresh rate?
The browser may be throttled by a power saving mode, a busy CPU or GPU, or because the tab is in the background. Laptops on battery and browsers with hardware acceleration turned off often run at lower rates. The refresh rate shown is the median frame interval, so it stays correct even when some frames drop.
How do I fix tearing on Linux?
Use a desktop with a compositor (most Wayland sessions are tear free), enable the compositor in Xfce or similar desktops, or turn on the TearFree option of the Intel or AMD X11 driver. On NVIDIA with X11, enabling Force Full Composition Pipeline in the NVIDIA settings removes tearing at a small latency cost.
Is the test safe for people sensitive to flashing?
The patterns move but do not flash the whole screen. Very high speeds with thin bars can still look flickery, so lower the speed or stop if it is uncomfortable.
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.