How to test for dead pixels before returning a monitor

Published April 20, 2026

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A new monitor with a dead pixel is annoying; a dead pixel discovered a week into the return window is expensive. Most retailers and manufacturers allow a return or exchange within a stated window, but only if the fault is verified. This guide walks through the 5-minute test that catches dead pixels, stuck pixels, backlight bleeding, and colour uniformity issues before you’ve gone past the return deadline — and covers what documentation you need if the return goes to warranty review.

Dead pixel vs stuck pixel vs sub-pixel

Dead pixel. A single pixel that never lights. On a white background it appears black; on any coloured background it also appears black. The transistor driving that pixel has failed; nothing you do to the software will fix it. This is the fault manufacturers accept as a return.

Stuck pixel. A pixel that always shows one colour regardless of what the operating system is drawing. Usually stuck red, green, or blue because one sub-pixel is permanently “on.” Sometimes fixable by running pixel-cycling software (“JScreenFix” pattern, FFmpeg pixel-flicker) for a few hours; frequently not. Most manufacturers don’t accept stuck pixels as a return unless you have multiple clustered together.

Sub-pixel defect. One of the three sub-pixels (R, G, or B) in a single pixel is stuck or dead. Harder to see — shows as a slight colour tint on solid colours. Generally not grounds for return.

The 5-minute test sequence

Use our LCD test tool in fullscreen on the display under test. The tool cycles solid colours — red, green, blue, black, white, yellow — one full-screen at a time.

1. Dim the room. Ambient light masks faint defects. A dark room at night is ideal; closing blinds and dimming overhead lights works during the day.
2. Run at native resolution. Set the OS display to the monitor’s rated resolution (often QHD 1440p or 4K UHD). Scaling down softens defects; running native shows every pixel at 1:1.
3. Cycle all six colours at full screen. For each colour, move your eyes slowly across the panel — top-left, top-right, middle, bottom-right, bottom-left. Spend 20–30 seconds per colour. Note any pixel that doesn’t match the surrounding field.
4. Photograph any defect. Use a phone camera with flash off, focused on the screen. Take a wide shot showing the overall screen and a close-up of each defect. Include the colour field that reveals the defect (dead pixel shows best on white; stuck pixel shows best on the opposite colour).
5. Disable Night Shift, Blue Light Filter, and HDR. Those features shift colour; defect detection needs neutral output.

Beyond dead pixels — other common new-monitor faults

Backlight bleed. On a solid-black field, look for uneven glow near the edges of the screen. Some bleed is unavoidable on IPS panels; severe bleed (bright corners, uneven stripes) is a defect.

Colour uniformity. On a solid mid-grey (50% grey), look for pink/green/yellow tints in different regions. Ideal uniformity is a perfectly even grey field; subtle variation is normal; strong regional tints indicate a panel defect.

Banding. On a smooth greyscale gradient (our LCD test can render one), look for visible steps between colour bands. 8-bit panels have some banding; 10-bit panels should be smooth.

Dead rows or columns. Rare but severe. An entire horizontal or vertical line that is dead or stuck. Unmistakable on the colour cycle. Grounds for immediate return.

What manufacturers and retailers accept

Acceptance policies vary by vendor and region. Common thresholds (check your specific vendor):

Dell, HP, LG, Samsung pro lines. Typically zero-dead-pixel guarantee on premium monitors; any dead pixel within 30 days is a return. Budget consumer monitors often require 3 or more dead pixels within a specified region before accepting a return.

Apple Studio Display, Pro Display XDR. Any defective pixel is grounds for exchange within the 14-day return window.

Amazon, Best Buy, big-box retailers. Their policies are usually more permissive than manufacturer warranty — a dead-pixel defect within the retailer’s return window (often 30 days) is accepted with proof.

Documentation that helps a return go through

If the return is contested or goes to warranty review, having documentation saves time:

• Phone photo of each defect. Close-up with the defect-revealing colour field visible.
• Timestamped screenshot of the LCD test running in fullscreen (most retailers accept this as evidence that the test was performed).
• Serial number of the monitor (usually on a sticker on the back).
• Purchase receipt with the purchase date.

What to do if you find a defect

Contact the retailer first; their return process is usually simpler than the manufacturer warranty. Most retailers process a return within 48 hours if the defect is verified in the test evidence. If the retailer’s return window has passed but you’re still within the manufacturer warranty (typically 12–36 months), escalate to the manufacturer with the same evidence set.

What to do if you find a stuck pixel

Before accepting that a stuck pixel is permanent, try the “pixel massage” technique: a damp microfibre cloth, gentle pressure directly on the stuck pixel for 5–10 seconds, repeat a few times. Alternately run a pixel-cycling pattern for 6–24 hours (rapid colour flickering at the stuck pixel’s location often unfreezes the liquid crystal). Fix rate is maybe 30–40% — worth trying before initiating a return if you’re past the easy return window.

Related tools

• LCD Test — the full-screen colour cycle used throughout this guide.
• Dead Pixel Testing Guide — deeper technical background on pixel mechanics.
• Camera Test — verify a new laptop’s webcam.
• Microphone Test — verify a new laptop’s mic.

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