Screen Test — Free Online Test

Our free online Screen Test cycles your display through eight solid-color fields (white, black, and the six primary/secondary hues) so you can spot dead pixels, stuck pixels, uneven backlight, and color-uniformity problems in a matter of seconds. Because the test runs full-screen in your browser, no drivers, no installs, and no permissions are required — it works on Windows laptops, MacBooks, Chromebooks, tablets, and phones alike. Whether you're inspecting a new machine, a used purchase, a warranty return, or a monitor before an important edit, a five-minute pass through these color pages will catch almost every panel defect a human eye can see.

How to use the Screen Test

Clean your screen with a dry microfiber cloth so dust does not masquerade as a dead pixel.
Dim the room slightly — reflections make small defects harder to see.
Click "Start Test" to enter full-screen mode. Your display will fill with a single color.
Slowly scan the entire panel corner to corner. Look for tiny black dots (dead pixels), bright always-on dots (stuck pixels), and any patches that look brighter or darker than the surrounding area.
Press the right arrow or click the next button to cycle through all eight colors. Repeat the scan for each.
Press ESC to exit full-screen mode when finished, then download or share your results.

How to interpret your results

A healthy display shows a perfectly uniform field of color with no visible dots, streaks, or blotches. A single dead or stuck pixel in the center of the screen is usually considered a defect worth returning; edge defects are often within manufacturer tolerance (ISO 9241-307). Uneven brightness patches on the white screen typically indicate backlight bleed or IPS glow — small amounts are normal on IPS panels but heavy bleed is a return-worthy fault. Colored tint bands on the black screen usually indicate a failing display cable or panel connector.

Common issues and what they mean

Dead pixels won't go away

True dead pixels are physically broken subpixels and cannot be repaired by software. Try our Pixel Repair tool for stuck (not dead) pixels — it often revives them within 15-30 minutes.

Backlight bleed on the black screen

A small amount of light leakage in the corners of an IPS panel is normal. Heavy, cloudy bleed that's visible during regular use qualifies for a warranty replacement on most brands.

One color looks tinted

If red looks pink or blue looks purple across the entire screen, your color profile is likely wrong. Reset the display profile in Windows Color Management or macOS Displays > Color settings.

Full-screen mode not activating

Some browsers block auto-fullscreen. Manually press F11 (Windows) or Ctrl+Cmd+F (macOS) after clicking Start.

When to run this test

Before accepting delivery of a new laptop or monitor.
Immediately after buying a used or refurbished device.
Before the return window closes on any new display purchase.
After a screen replacement or repair to verify the technician's work.
Before an important color-critical task (photo editing, print prep).

Dead pixel policies at Dell, HP, Lenovo, Apple and Samsung

Every major manufacturer publishes a pixel-defect threshold, and knowing yours before you call support decides whether you get a replacement panel or a polite refusal. Most consumer lines are warranted to ISO 9241-307 Class II, which tolerates a handful of subpixel faults per million pixels. Premium and professional lines are often warranted to Class I, meaning zero bright dots.

Dell warrants its Premium Panel Exchange on most XPS, Alienware and UltraSharp monitors: a single bright pixel qualifies for a free replacement during the standard warranty. HP typically applies a graded policy where centre-of-screen defects are treated more seriously than edge defects. Lenovo follows ISO Class II on most ThinkPad and IdeaPad models but upgrades to a stricter standard on its X1 and P-series panels.

Apple does not publish a numeric threshold; Genius Bar staff assess visibility at normal viewing distance, and a clearly visible dot on a Retina display is usually accepted. Samsung and LG monitors generally require multiple defects on consumer lines but offer zero-bright-dot guarantees on professional models. Run this test, photograph the defect against a solid white and a solid black field, and note where it sits relative to the screen centre before you open a case.

Return windows: what US, UK and EU buyers should know

In the United States, retailer return windows are the practical route to a replacement. Best Buy allows 15 days for most laptops and 60 days for My Best Buy Plus and Total members; Amazon gives 30 days on most electronics; Costco has no fixed deadline on many categories but caps laptops at 90 days. A dead pixel found in week one is a no-questions return; the same defect found in month four is a warranty claim with a higher bar.

In the UK, the Consumer Rights Act 2015 gives you 30 days to reject faulty goods for a full refund, and up to six months during which the retailer — not the manufacturer — must prove the fault was not present at delivery. Online purchases also carry a 14-day cooling-off period under the Consumer Contracts Regulations, which lets you return a working laptop simply because you changed your mind.

In the EU, the Sale of Goods Directive guarantees a two-year legal conformity period in every member state, with a one-year presumption that any defect existed at delivery. Distance selling adds a 14-day withdrawal right. In all three regions the retailer is your first contact, not the manufacturer — and a dated screenshot from this test, taken within days of delivery, is the evidence that keeps the conversation short.

What this test can and cannot detect

A browser-based solid-colour test is excellent at what your eyes are good at: locating always-black dots, always-lit dots, colour tint bands, cloudy backlight bleed and IPS glow. Those are the defects that matter most for a return decision, and they are exactly what a technician looks for during an intake inspection.

There are limits worth being honest about. This test cannot measure absolute luminance in cd/m², colour accuracy in Delta-E, gamma tracking, or panel uniformity in percentage terms — all of those require a hardware colorimeter. It also cannot distinguish a failing panel from a failing display cable when the symptom is intermittent, though a defect that changes when you flex the lid is almost always a cable or connector issue rather than the panel itself.

For a complete display assessment, pair this test with the gradient test for colour banding, the brightness test for black crush and clipping, and the refresh rate test to confirm the panel is actually running at its rated Hz rather than a lower fallback mode after a driver update.

Frequently asked questions

Is this dead pixel test accurate?

Yes. It uses the same full-screen solid-color technique that manufacturers and repair shops use for panel inspection. A careful pass through all eight colors reveals most visible pixel faults.

What is the difference between dead and stuck pixels?

A dead pixel is completely black on every color — the transistor driving it has failed and it cannot be fixed by software. A stuck pixel is locked on one color (usually red, green, or blue) and can often be revived by rapidly cycling colors through our Pixel Repair tool.

Will this test damage my screen?

No. The test displays static solid colors briefly. It is completely safe for OLED, IPS, VA, and TN panels alike.

How many dead pixels are acceptable?

Most manufacturers use ISO 9241-307 Class II, which permits up to 2 bright dots, 2 dark dots, or 5 subpixel faults per million pixels. However, most retailers offer replacements for any pixel defect within the return window.

Can I run this test on my phone?

Yes. The screen test works on any device with a modern browser. Rotate to landscape for the best coverage on phones and tablets.