A scanner apparatus and method includes an optical scanner, at least one movable carriage associated with the optical scanner, and a point sensor that rides the movable carriage to measure a slow scan document width associated with a document scanned by the optical scanner. The point sensor moves in a slow scan direction with respect to the document scanned by the optical scanner. The point sensor also includes a single moving size sensor that improves a resolution by which a size associated with the document is determinable.