Convert from button measure to kilometer

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 (kilometer)
The kilometer is one of the most common metric units of length or distance. One kilometer equals exactly 1000 meters (metres), about 0.62137119 mile, 1093.6133 yards, or 3280.8399 feet.