It's dependent on the resolution of your monitor.
For instance, on my 21 in. CRT monitor, I have to set the resolution to 1152 X 870 to see an 8.5 X 11 document at full size - which will not accomodate the full height. If I lower resolution, it gets bigger. Raise resolution and things get smaller.
This is the same with all programs, and not related to ID.