Use this useful tool to convert typography choosing one of the 15 units of measurment included in this app (with the availability to add custom units), that are:
twip, meter, centimeter, millimeter, character (X), character (Y), pixel (X), pixel (Y), inch, pica (computer), pica (printers), en, PostScript point, point (computer), point (printers).
For every units of measurment are also included formulas to convert that unit as you want.