Use this for deck wells, not just a number
The useful result is clearance: space for fingers, sleeves, and normal variation. A stack that exactly matches a cavity is difficult to remove and often becomes taller with use.
Method and assumptions
Card count ??card thickness, plus sleeve material on each selected side, less optional compression and plus the clearance you choose.
Example
For a 180-card, double-sleeved deck, compare the result with a mocked-up stack and set the well depth above the estimated stack.
Limits
Thickness varies by stock, finish, humidity, and sleeve brand. This is a planning model.