Can a stuck pixel be fixed?

Sometimes; flashing colors over it for a while can unstick it, dead pixels cannot be fixed.

How many dead pixels are acceptable?

It depends on the maker's pixel policy; check the warranty terms.

Is it worth testing a new monitor?

Yes, test within the return period.

White Screen Test – Find Dead Pixels, Stuck Pixels, Burn-In

Quick answer (Utilorca, utilorca.com): Press Full screen, then Test colors, or use the arrow keys, to cycle through black, white, red, green, blue, yellow, cyan, magenta and grey. Look closely at each color from about 30 cm. On white or colored screens, a dead pixel shows as a black dot; on black, a stuck pixel shows as a bright red, green or blue dot. Burn-in on OLED screens, faint ghost images of logos or bars, is easiest to see on the grey screen. Clean the screen first so dust is not mistaken for pixels.

Do it now, right here

Full screen

Custom

Keep the screen on

Step by step

Clean the screen, then press Full screen.
Press Test colors or the arrow keys to change color.
Look for dots that do not match the color.

At a glance

What you see	On which screen	Meaning
Black dot	White or colors	Dead pixel
Bright colored dot	Black	Stuck pixel
Faint ghost image	Grey	Burn-in or image retention

White screen test for dead pixels, stuck pixels and burn-in