@Anonymous hi,
i see your model space is defined in meters and your paper space is defined in millimeters. this drags you to define these viewport scale ratio:
1xp is 1:1000
2xp is 1:500
2.5xp is 1:250
ps plot scale is 1=1 fix - am i right?!
all of this is due to AutoCAD limited to plot only in mm (or inch)
although this is the 'common' way to define drawings in AutoCAD, i would like to present you another way of thinking to do this and it is to synchronize paper space units to model space units e.g to move to meters.
(do not change your current work only we will do a test on another layout or saveas to new name)
let say you want to set A0 sheet size, create a new layout and delete the viewport. open page setup dialog and choose your large printer, choose A0 sheet size and set plot scale to 1000=1 and close dialog.
zoom all and create a viewport to maximize the space. now go to Format\Scale list (scalelistedit) and do reset to metric scale and add your favorite scale (e.g 1=1000, 1=500, 1=250 etc)
show the Viewport toolbar (if it's not already there) and select the viewport and choose 1:1000 or 1:500
now tell me isn't it more convenient to see the real scale 1:1000 or 1:500 or 1:250 on the viewport toolbar?
(instead of 1 or 2 or 2.5)
moshe