Convert from point [Britain, US] to button measure

Unit Definition (point [Britain, US])
The unit of measure for the height of type, defined as 1/72 of an inch* or 0.3527777778 mm (*small differences occur in this unit between countries, the variables lying between 0.188 and 0.4mm)

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.