Screen Tearing Test

What Is Screen Tearing?

Screen tearing is a visible discontinuity that can occur when the display shows portions associated with different rendered frames during one scan. A vertical edge may appear horizontally offset across one or more tear lines. It is often most noticeable during steady horizontal camera movement or on crisp vertical features. Tearing is different from blur, which softens motion, and stutter, which disrupts timing.

The exact presentation path includes the application, graphics API, compositor, synchronization settings, operating system, display connection, and panel. A browser page cannot inspect every stage. The screen tearing test supplies repeatable moving geometry that can make a discontinuity easier to notice, but it cannot automatically certify whether the hardware is operating correctly.

How a Screen Tearing Test Works

The pattern contains broad moving vertical bars crossed by fixed horizontal guide lines. Position is calculated from elapsed time in pixels per second, so speed remains consistent when the callback cadence changes. If part of a moving edge is presented from a different temporal position, the horizontal guides make the offset easier to locate. Direction and speed controls vary the inspection conditions.

The animation uses the browser’s synchronized frame callback, so modern composited browsers may avoid tearing in circumstances where an unsynchronized native game would show it. A clean browser result does not prove that every application or fullscreen mode is tear-free. The tool demonstrates and inspects the browser display path currently in use.

How to Get Started

Place the window entirely on one display, select a moderate speed, and follow a vertical edge without staring at one fixed pixel. Switch direction and try a faster pass. Fullscreen increases the pattern area and can make a horizontal discontinuity more apparent. If motion is uncomfortable, pause immediately and use a lower speed.

1. Begin at 480 pixels per second and watch where colored edges cross the horizontal guide lines.
2. Try both directions, then increase speed while keeping the same display and browser conditions.
3. Repeat only long enough to observe comfortably; record what you saw rather than expecting an automatic verdict.

Tearing vs Stutter

Tearing usually appears as a spatial split: different horizontal regions show an edge at different positions. Stutter appears as uneven motion over time, such as a pause followed by a jump. Both can occur together, and blur can make either harder to see. The FPS drop test detects unusually long browser intervals, while this moving-line test relies on visual inspection of spatial continuity.

A camera recording may show bands caused by the camera shutter interacting with the display rather than what your eyes see directly. Slow-motion video can be informative only when capture and display timing are understood. The page therefore avoids asking users to upload an image for automated diagnosis or claiming that a screenshot proves the absence of tearing.

V-Sync, VRR, and Refresh Mismatch

V-Sync coordinates presentation with display refresh to prevent mid-scan changes, often at the cost of queueing or rate behavior when a frame misses its window. Variable refresh rate technologies let a compatible display adjust refresh timing within a supported range. Frame limiters can keep production within that range. Implementations and latency tradeoffs vary, so no one setting is correct for every system.

A mismatch between application frame production and fixed display refresh increases the conditions in which unsynchronized presentation can tear. The browser compositor commonly synchronizes web content, limiting what this test can reproduce. Use the pattern to inspect the current browser path and the FPS-vs-Hz guide to understand the concepts, not to override application-specific documentation.

When a Tearing Test Is Useful

The tearing test helps after changing a display mode, synchronization setting, cable path, or compositor-related option, provided that change affects browser presentation. It can help distinguish an edge split from general blur and offers a consistent moving subject for comparing two settings. Keeping speed, direction, resolution, and refresh mode constant makes observations more useful.

If tearing occurs only in a native game, reproduce it inside that game and review its presentation mode, V-Sync, frame limiter, and VRR status. This web tool does not access those settings. Likewise, intermittent signal faults, pixel defects, and image retention require different tests and should not be labeled as tearing solely because motion looks unusual.

Limitations of Browser-Based Tearing Tests

Browser compositing can prevent or transform tearing, and windowed presentation may differ from exclusive fullscreen software. The pattern cannot detect tear lines computationally because the page does not receive a camera view of the physical output. It also cannot verify VRR, cable capability, scan direction, or hardware health. Fullscreen is a convenience, not a switch to native exclusive presentation.

Use the screen tear test as a controlled visual aid. Stop if fast patterns cause discomfort. A result may vary with browser, operating system, monitor, refresh setting, power mode, and system load. No observed tear proves a component is faulty, and no clean run guarantees that another workload or presentation mode will remain tear-free.