Monitor Tester

This tool uses your browser's rendering engine and the requestAnimationFrame API to measure real-time display performance — and provides fullscreen solid-color screens for pixel defect inspection. No software to install, no calibration hardware required.

Refresh Rate Measurement

The tester counts actual rendered frames per second using requestAnimationFrame callbacks. Each callback timestamp is compared to the previous one to calculate instantaneous FPS. Over time, the average converges on your display's true refresh rate. At 60 Hz you'll see ~60 FPS; at 144 Hz, ~144 FPS. Close other tabs and applications for the most accurate measurement.

Dead Pixel Test

The dead pixel test displays a solid color in fullscreen mode. Cycle through red, green, blue, white, and black backgrounds and carefully examine every region of your screen. Dead pixels appear as tiny dots that remain black (or a wrong color) against the solid background. Examine corners and edges — defects often cluster near panel borders.

Gradient & Banding Test

The gradient test displays smooth color transitions to reveal color banding — visible steps between shades instead of smooth gradients. Banding indicates limited color depth (6-bit panels show more banding than 8-bit or 10-bit panels) or aggressive color compression in your display cable or settings.

What You Can Discover

• Dead pixels: Permanently non-functional sub-pixels that appear as black dots.
• Stuck pixels: Sub-pixels stuck on one color (always red, green, or blue). Sometimes fixable.
• Backlight bleed: Light leaking from edges on IPS panels, visible on black backgrounds.
• IPS glow: Silvery glow in corners when viewed off-angle, common in IPS panels.
• Clouding: Uneven brightness patches on VA panels, visible on gray backgrounds.
• Actual refresh rate: Verify your monitor runs at the advertised Hz.

LCD Panels

IPS (In-Plane Switching): Best color accuracy and viewing angles. Prone to IPS glow and backlight bleed — the dead pixel test will reveal these. Common in professional monitors (Dell UltraSharp, LG UltraFine, BenQ PD series). VA (Vertical Alignment): Best contrast ratio and deep blacks. Check for clouding and response time smearing. Common in curved gaming monitors (Samsung Odyssey, MSI MAG). TN (Twisted Nematic): Fastest response times but worst viewing angles and color. Dead pixel tests should be done straight-on.

OLED & Mini-LED

OLED displays (LG OLED, Samsung QD-OLED, ASUS ROG, Dell QD-OLED) don't have backlight bleed by design — each pixel emits its own light. The dead pixel test checks for dead sub-pixels and burn-in. Mini-LED (Apple Pro Display XDR, ASUS) can show halo effects around bright objects that the gradient test can reveal.

Laptop Displays

Built-in laptop screens work perfectly. Run the fullscreen test to check for dead pixels before your warranty expires. Most laptop displays are 60 Hz IPS — the refresh rate test will confirm.

External Monitors & TVs

Move the browser window to the display you want to test, then enter fullscreen. Works with any connection — HDMI, DisplayPort, USB-C/Thunderbolt, VGA (analog — less precise for pixel tests). For refresh rate verification, ensure your OS is set to the monitor's native rate (check Display Settings > Advanced > Refresh Rate).

Refresh Rate Shows 60 Hz on a High-Refresh Monitor

• OS settings: Check Display Settings → Advanced → Refresh Rate. Many monitors default to 60 Hz until manually set higher.
• Cable limitation: HDMI 1.4 caps at 60 Hz for 4K. Use HDMI 2.1 or DisplayPort 1.4 for 4K@120Hz+. DisplayPort is preferred for high refresh rates.
• V-Sync or frame rate cap: Disable V-Sync in browser settings. Chrome: chrome://flags/#disable-frame-rate-limit.
• Power saving: Laptop GPU power management may limit refresh rate on battery. Plug in or switch to performance mode.

Dead vs Stuck Pixels — Can They Be Fixed?

• Dead pixels (black): Usually permanent. The transistor controlling the sub-pixel has failed. Covered by warranty if you have more than the manufacturer's threshold (typically 3–5 for consumer monitors, 0 for Class 0 panels).
• Stuck pixels (constant color): Sometimes fixable. Try a pixel-cycling video (rapidly flashing colors) run on the affected area for 30–60 minutes. Gentle pressure with a soft cloth on the stuck pixel while cycling colors can also help. Success rate is roughly 50%.

Backlight Bleed Assessment

• Display a black fullscreen. Light leaking from edges/corners is backlight bleed.
• Some bleed is normal on IPS panels — it's a design trade-off for better color and viewing angles.
• Excessive bleed that's visible during normal use (dark movie scenes, etc.) may warrant a warranty claim or return.
• Take a photo in a dark room with your phone camera to document the extent — useful for warranty claims.