My internal dimensions are to the edge at approximately 18x9x4cm. (Deviations of up to 5 mm in the two chests)
I have to fit each filled with 200 (400x50cent) and 120 (400x20cent and 80x50cent). This is just above the edge of 4cm, it can therefore fall out a few coins when you open if you are not careful. It should be so ...
As a basis for calculating the filling I have known the extent of the coins used by Wikipedia (volume = d² * PI / 4 * h) and adopted the packing density of 64%. (See Abstract of Berryman, JG Random Close Packing of Spheres and Hard Disks. (1983))
Was easier than it sounds, and worked perfectly. See also the set photo.
