I've got a problem with a layout view scale in ArcGIS. When I'm vewing a map in layout view and then print it in scale for example 1:10000, 10cm isn't 10 but 9,5. I've checked a 100% size in layout view before print and that's teh same problem 10cm scale bar is 9,5. Moreover a A4 paper format isn't 21cm as it should be but it's 20cm. I really don't know where is the problem. Can anyone explain me what is going on?