Touch Screen Test

How to use

1. Open the page on the affected phone, tablet, or touch-enabled display, then choose Grid, Draw, Edge, Multi-touch, or Ghost watch. This page reads real touch Pointer Events, not mouse or pen input.
2. For Grid, Draw, Edge, or Multi-touch, optionally enter Fullscreen while idle, then select Start. Exiting Fullscreen during capture interrupts and freezes that run so evidence from different surface geometry is not mixed.
3. Tap Start and use a finger on the marked test surface. Mouse simulation is rejected so it cannot be mistaken for touch input.
4. In Grid mode, move one finger across the full 8 × 12 grid. Retest untouched cells deliberately; a cell missed in one run is not automatically a dead area.
5. In Draw mode, draw continuous lines, lift your finger, and repeat in different areas. Completed paths remain visible so you can compare them with draw break hints.
6. In Edge mode, touch all four edges and corners slowly. Browser navigation gestures can intercept input near the screen boundary; set up Fullscreen before Start where the browser supports it.
7. In Multi-touch mode, place two or more separated fingers on the surface and move them independently. Review the colored paths, the observed maximum, and the browser-reported max touch points; neither is a hardware certification.
8. For Ghost watch, clean and dry the screen, remove accidental contact, place the device still, select Start, and keep hands and objects off the page for the full 20-second observation window. It counts only browser-reported touch contact starts.
9. If the unexpected-touch symptom is condition-specific, repeat after changing one variable: compare unplugged when charging is relevant, or without a tight case or problematic protector when practical and safe. Do not assume those accessories are the cause.
10. Tap Stop to freeze the current results. Tap Reset before a clean run; Reset returns the session to Ready and does not start capture.
11. Switching modes clears the previous mode’s metrics. Basic testing still works when Fullscreen is unavailable.

What the result means

• Session shows Ready before capture, Running after Start, Stopped when results are frozen, or Interrupted after focus, visibility, or another pointer interruption. Only a running session records touch input.
• Grid coverage is the percentage of cells where the browser received a touch pointer event. Higher coverage means more areas were reached in this run; lower coverage can simply mean you did not cross the full surface.
• Untouched cells received no touch event during this run. Touch them deliberately in another clean run before treating an area as suspicious; one run cannot identify a hardware dead zone.
• Max simultaneous is the largest number of touch points the browser reported at once in this run. Device, operating system, browser, and system gestures can limit it, so it is not the manufacturer-certified multi-touch capacity.
• Browser-reported max touch points is navigator.maxTouchPoints, a capability value exposed by the browser/device. Compare it with the observed run; it does not guarantee every gesture exposes every contact.
• Completed paths are paths saved after a normal finger lift. Their count is not a touch-quality score, and the paths remain visible after pointerup and Stop.
• Cancelled paths end through pointercancel, often after a browser or system gesture. Focus or visibility interruption freezes active contacts as interrupted paths. These browser-session events do not by themselves indicate screen damage.
• Draw break hints flag larger gaps between samples in a path. Fast movement, browser event coalescing, scheduling, or an interruption can cause them; they are not a definite diagnosis of dropped touch input.
• Mouse rejects counts mouse PointerEvents rejected from touch metrics. Pen, stylus, and unknown non-touch pointer types are also ignored, but they are not added to this mouse count.
• Edges and corners show whether this run received touch events in the corresponding boundary areas. Navigation gestures can interfere there, so repeat missed boundaries slowly and in another orientation.
• Ghost watch reports touch contact starts received while the page instructed you to remain hands off. A quiet 20-second run means no unexpected touch was reproduced in that browser window; a reported contact is evidence to repeat and troubleshoot, not confirmation of a hardware fault.
• Reset or switching modes clears paths and metrics. Stop freezes the current results, while completed paths persist after you lift a finger.

Limitations

• OS gestures may cancel touches on iOS Safari or Android Chrome.
• Mouse, pen, and stylus simulation is not a valid touch-screen test; only touch PointerEvents enter touch metrics.
• Does not measure hardware touch sampling rate.
• Browser paths cannot distinguish a hardware fault from accidental contact, palm contact, system gestures, browser behavior, or screen contamination. Pointer Events are browser-exposed touch evidence, not raw hardware telemetry.
• Ghost watch cannot inspect browser chrome, the lock screen, system UI, other apps, or touches the browser does not expose. Its 20-second window is a product observation window, not a diagnostic threshold.

Troubleshooting

No touch points appear

Confirm the device has a real touch screen, tap Start, use a finger instead of a mouse, and keep the tab visible. Try another supported browser before concluding that hardware has failed.

Page scrolls while drawing

Start the session and draw inside the marked surface, where running mode uses touch-action: none. Browser chrome and areas outside the surface can still scroll.

Edge or corner touches do not register

Repeat slowly and try both portrait and landscape. Operating-system navigation gestures may intercept edge input. Enter fullscreen while idle, then Start; exiting fullscreen interrupts the run so two surface geometries are not mixed.

Multi-touch count is lower than expected

Keep fingers clearly separated on the marked surface and avoid browser or operating-system gestures. The device and browser may expose fewer points than the manufacturer’s specification.

Paths are cancelled or the session is interrupted

Keep the page foregrounded and avoid switching tabs, opening notifications, or using system gestures. Tap Reset and repeat a clean run.

Draw break hints appear

Move more slowly, repeat the same path, and compare several clean runs. Browser scheduling and event coalescing can create gaps as well as an interrupted touch.

Unexpected touch paths appear

Use Ghost watch after cleaning and drying the screen and removing accidental contact. If relevant, compare one later run unplugged or without a tight case or problematic protector. Repeated browser contacts justify manufacturer diagnostics or support, but do not confirm a hardware fault.

Fullscreen is unavailable

Basic touch testing still works. This is a browser capability limit; try landscape orientation or hide browser controls where possible.

Related tools

• Dead Pixel Test

  Check a monitor, laptop, phone, or tablet for dark, bright, or fixed-color pixel anomalies with nine full-screen solid-color patterns. You inspect the screen; the browser cannot diagnose physical pixels.

• Screen Resolution

  See browser-reported screen and viewport CSS sizes, DPR, and an estimated device-pixel size. Refresh after display changes; this is not native panel telemetry.

• Refresh Rate Test

  Estimate the refresh rate reaching this browser window from requestAnimationFrame timing. Review median frame interval, timing consistency, interruptions, and repeatable local results without treating browser Hz as panel telemetry.

FAQ