The complete screen test routine: patterns, interpretation, and limits
A screen test displays known-good reference patterns — solid colors, grayscale steps, gradients, color bars, and motion sequences — so visible defects stand out against them. Run the full set here, free, in your browser: no download, no account. Test patterns render locally, and your pixel markings, notes, and reports stay on your device. We collect anonymous usage statistics to improve the tools — never your observations.
What a complete screen test covers
Solid colors are the foundation: a full-screen white reveals dark dots and uneven backlight, black reveals light bleed and stuck pixels, and pure red, green, and blue isolate individual subpixels. Any spot that behaves differently from its surroundings on a solid field is worth recording — after cleaning the screen and re-verifying it on at least two colors.
Grayscale steps and gradients expose what flat colors cannot: backlight bleed in the corners, vignetting, dirty-screen effect (DSE) — the cloudy patches visible on camera pans in dim scenes — and banding, where an 8-bit panel quantizes a smooth ramp into visible stripes.
Motion patterns complete the picture, revealing response-time smear and refresh behavior that static images never show. Together these checks cover the visible display faults you might notice in daily use; deeper topics are covered by the dedicated dead pixel, uniformity, and ghosting guides.
The 5-minute full-panel routine
Minute 1 — set up. Wipe the screen with a microfiber cloth (a large share of "dead pixels" are dust), dim the room, and warm the panel for ten minutes if it was off. Press F to enter fullscreen so browser chrome does not cover the test area.
Minutes 2–3 — sweep the solid colors. On white, scan for dark dots and uniformity; on black, for bleed and bright defects; then cycle red, green, and blue. Work the screen in a grid rather than randomly — that is how factory QC does it. Any suspicious dot gets verified with the dedicated dead pixel test or marked with the Pixel Locator.
Minutes 4–5 — check the grays and motion. Step through the gray levels for tint and DSE, run the gradient for banding, and let the sliding bars cross the panel to expose ghosting or smear. On OLED panels, add the 50% gray scan from the burn-in test; on high-refresh displays, confirm the panel is actually running at its rated Hz with the refresh rate test.
When to run a screen test
The first week of ownership is the critical window: defect rates are highest in new panels and return windows are short. Photograph anything you find against the failing test color — evidence makes exchanges frictionless.
Used-monitor purchases are the second checkpoint. A two-minute sweep for dead pixels, burn-in, and uniformity belongs in every pre-purchase inspection and gives you negotiating leverage on the spot. Bring the test up on your phone and cast or load it on the seller's setup.
Then re-test occasionally. Panels age: backlight character drifts, OLED emitters wear unevenly, and a monthly glance at gray fields catches problems while they are still small. After any GPU driver update or cable change, re-verifying native resolution and refresh rate takes thirty seconds and prevents the classic silent 60 Hz downgrade.
What a browser screen test can and cannot do
Browser-based patterns make certain visible screen problems easier to notice: suspicious pixels, uneven-looking fields, visible banding, and motion artifacts where the relevant test is supported. They are practical first checks — the same primitives a factory test bench uses.
What they cannot do: visual inspection does not measure calibrated brightness, color accuracy, color gamut, input lag, or most panel specifications. Browser color management, OS scaling, display settings, graphics hardware, and the panel itself all affect what you see. For color-critical work or numerical measurements, use suitable measurement hardware — the color calibration guide explains where that line sits.
Device compatibility and browser limitations
The tests run in supported modern browsers on monitors, laptops, tablets, phones, and TVs with a built-in browser. Fullscreen behavior, scaling, and remote-control support vary by device — verify that the pattern actually fills the intended display before judging anything.
Known limits: browser-reported display information (resolution, pixel ratio, measured refresh rate) is indicative, not a laboratory measurement. Battery-saver modes, night-light color shifts, and background load can distort what you see — disable them and close other tabs before drawing conclusions.
Frequently Asked Questions
How do I test my monitor online?+
Open a supported screen test, use fullscreen mode when available, and inspect a series of solid colors. Follow with grayscale, gradient, uniformity, or motion tests based on what you want to check.
How do I check for dead pixels?+
Display solid white, black, red, green, and blue backgrounds. Scan the whole panel for persistent dots or subpixels that differ from nearby pixels. Clean the screen first and repeat suspicious findings to rule out dust or reflections.
Can a browser test confirm that my monitor is defective?+
No. It can help reveal visible anomalies, but it cannot confirm every hardware fault. Retest under suitable conditions and consult the manufacturer's diagnostic guidance and warranty policy when necessary.
Can I use an online screen test on a laptop or TV?+
Many modern devices can display browser-based test patterns, but fullscreen support, browser availability, scaling, and remote-control behavior vary by device. Use the device's supported browser and verify that the pattern fills the intended display.
Can a screen test measure color accuracy or brightness?+
Visual patterns can reveal some visible color and tone issues, but they do not replace calibrated measurement hardware for numerical brightness, color accuracy, or gamut measurements.
What should I do if I find a suspicious pixel?+
Repeat the test on multiple solid colors, inspect the location carefully, and record the observation. Check the manufacturer's pixel-defect policy before deciding whether the result qualifies for service or return.
Is a browser-based monitor test a replacement for professional calibration?+
No. It is useful for visual inspection and basic troubleshooting. Color-critical work and reliable numerical measurements require an appropriate calibrated workflow and, where necessary, measurement hardware.