A bigger monitor won't really do anything since the UI coordinate system is always rendered at a base height of 768 and adjusts the width according to the aspect ratio.
According to the following data, the following formula should give you the needed scale.
Code:
Scale = BaseHeight / AspectRatio / RequiredWidth
BaseHeight is always 768 and RequiredWidth seems to be 1476.
For a 5:4 monitor:
Code:
0.6504 ~= 768 / (5/4) / 1476
For a 4:3 monitor:
Code:
0.6938 ~= 768 / (4/3) / 1476
For a 16:9 monitor:
Code:
0.9250 ~= 768 / (16/9) / 1476