On a less technical level, a further consideration to be weighed when buying a scanner is the maximum size image a particular unit can scan. Most sheetfed scanners can easily scan documents up to 8.5" wide and 14" long. Among flatbed scanners, particular units are divided between those that can scan only a letter-size (8.5" x 11") page and those that can handle a full legal-size (8.5"x 14") scan. Letter-size scanners are also sometimes referred to as A4-sized, in reference to the European paper sizing system. In choosing a scanner, consider how important it is to you to have a full legal-sized scanning bed. Most users have little need for this feature, but real estate agents and others who work with documents in that format will appreciate the flexibility.

One warning on scanning area size: an increasing number of scanners are using lenses to increase the resolution available in one part of the scanning bed, by concentrating the light reflected off the image. This is very useful for scanning slides and other materials that benefit from being scanned at high resolution, but it can be misleading if the high-resolution area is only a small part of the overall scanning area. Be on the lookout for scanners offering dual resolutions, and realize ahead of time that the highest resolution will probably only be available for small images.