it should be able to easily read up to about 1.5" (4 cm) less than the media width, and with some effort can get lower. As pat said, it's between the outside 2 pinch rollers, i think they have blue tabs on that printer. The printer doesn't read the sheet width, but the distance between those 2 rollers, so if they aren't at the edge of the media, it won't read the whole width.