Quoted By:
Each Pokemon stored in the in game PCs is held in a 136 byte value.
So let's say 1 kilobyte, or 1,024 bytes, is 7.5 Pokemon (it is, give or take 0.05 of a Pokemon).
So 1 kilobyte is 7.5 Pokemon, and Pokemon Bank contains a maximum of 3000 Pokemon.
3000 Pokemon are, going by the 7.5 Pokemon = 1 kilobyte value, exactly 400 kilobytes.
This service is $5 per year for a total amount of cloud storage effectively equal to 0.4 megabytes.