Convert from button measure to fuss [German]

Unit Definition (button measure)
The button measure is a unit of distance equal to 1/40 inch (0.635 millimeter), used to measure the thickness of buttons.

Unit Definition (fuss [German])
The length of the fuß (or fuss) is the German foot. It varied somewhat; the Viennese version was equal to 12.444 inches or 31.608 centimeters, while the Rheinfuss (Rhine foot), used in much of western and northern Germany, was equal to 12.357 inches or 31.387 centimeters. In Bavaria a shorter fuß of about 29 centimeters was used. There's no change in the plural.