What is the maximum length of a VGA cable?

Information deterioration only begins on a noticable level after the first 100 ft or so.

There are two factors that greatly affect the image quality. One is the VGA driver - the display card. Many are designed to drive only short distances and do not perform well above 10 to 20 feet. The other is the cable itself. VGA is a high resolution video signal and demands a properly designed cable to carry it over a long distance. Many short VGA cables do not comply with the transmission standards for long distances. They work over a length of 5 feet or so but for long distance transmission, 75 ohm co-ax cable is needed for each of the red, green and blue signals.

Given a proper video driver in the display card, several hundred feet is possible if the right grade of video cable is used to carry the signal. This type of cable is not a standard product in most cases, so it will need to be made to order. Standard cables over 100 feet are rare.