Hello Everyone,
I would like to clear few of my doubts in the process of creating a new footprint for a component.

After creating the footprint , on what basis the padstack height and width are assigned for different layers.

For instance,
in a particular footprint, i saw
the pad width and height for top layer = 1.47mm
while the same for Solder Mask Top = 1.80mm
and for drill drawing it is = .86mm

Kindly guide me on how to arrive at suitable pad values like the one described above, when creating a new foot print.
any calculations needed to do that?

Thanking all,
suresh.