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Display Tests

Choose a display test according to what you need to observe: solid colours for visual pixel inspection, browser-reported dimensions for screen and viewport information, or frame timing for a refresh-rate estimate. These methods answer different questions; none certifies the physical panel or its advertised specification.

Choose a test

  • Monitor Test

    Inspect manually selected colors, gradients, uniformity and geometry patterns without automatic defect claims.

  • Dead Pixel Test

    Run full-screen solid colours to reveal dead, stuck or discoloured pixels on your display.

  • Screen Resolution Test

    See the resolution, viewport size, pixel ratio and colour depth your browser reports.

  • Refresh Rate Test

    Estimate the refresh rate your display is actually running at, with the limits of the method stated.

Inspect pixels with deliberate solid backgrounds

Dead Pixel Test displays nine solid colours for you to inspect. Look for a suspicious location that stays different from its surroundings across several backgrounds. A dark dot may disappear into black; a fixed coloured point may blend into a matching colour. Pause on each background and scan edges and corners rather than cycling quickly.

Rule out surface contamination and reflections before assigning a label such as dead or stuck pixel. Check the display with the screen off and clean only according to the manufacturer’s instructions. The browser does not photograph the panel or automatically detect defects. Your clear, suspicious or unsure answer is an observation, not an electronic diagnosis or warranty decision.

Screen dimensions and viewport dimensions are different

Screen Resolution Test reads the size reported by the browser’s screen API and the current page viewport. The screen is the browser’s view of the display; the viewport is the space available to the page. A resized window, browser toolbar or mobile interface can change the viewport without changing the physical monitor. Multi-monitor behavior depends on the browser and operating system.

These dimensions are expressed in CSS pixels. A CSS pixel is a layout unit, not necessarily one physical panel pixel. Device pixel ratio, or DPR, describes the browser’s device-to-CSS scaling relationship and may be influenced by system scaling and page zoom. Multiplying screen dimensions by DPR can provide context but is not guaranteed to recover native panel resolution.

Read reported information without inventing specifications

Available screen area can exclude operating-system interface regions. Reported colour depth and orientation also come from browser APIs, whose values may be limited or standardized for privacy. They do not establish panel bit depth, HDR performance, accurate colour reproduction or the monitor model. A changed number after zooming is a clue about reporting and scaling, not evidence that physical pixels changed.

Use operating-system display settings and the manufacturer’s documentation when you need the active output resolution or native panel specification. On a phone, turning the device can update orientation and available layout space. Compare readings after the layout settles. A browser page cannot promise consistent physical-display reporting across all devices.

Refresh-rate testing estimates browser frame cadence

Refresh Rate Test samples consecutive requestAnimationFrame timestamps. It skips a 500 ms warm-up, collects approximately 4.5 seconds of intervals and estimates Hz from the median interval. Longer gaps are reported separately, and sample count and consistency help put the estimate in context. This is browser animation scheduling, not a direct panel-controller measurement.

A 60 Hz-like estimate does not prove a higher-refresh monitor is limited to 60 Hz. Browser scheduling, power saving, load, window placement and operating-system configuration can constrain the observed cadence. Variable-refresh displays can change timing with content and settings. Repeat with the tab visible, keep conditions similar and check system display settings before drawing conclusions.

Fullscreen helps coverage, not certification

Fullscreen can expose more of the display during pixel inspection and reduce browser chrome. If the browser refuses fullscreen, the tool can only cover the available window. It cannot inspect areas outside that window. Fullscreen availability does not establish native resolution, remove all scaling or guarantee a more accurate refresh estimate.

Keep brightness and viewing conditions comfortable. Avoid pressing on suspicious marks or using rapid-flashing repair claims. These tools do not calibrate colour, measure brightness, quantify motion blur or provide manufacturer-grade panel certification. Browser-reported dimensions, frame intervals and inspection answers remain local and are not sent to analytics. For persistent anomalies, repeat the observation and consult the appropriate display support policy.

Read the methodology for measurement principles and the privacy policy for data handling. Return to all device tests to check another part of your setup.

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