Miles per minute to millimeters per second conversion calculator above calculates how many millimeters per second are in 'X' miles per minute (where 'X' is the number of miles per minute to convert to millimeters per second). In order to convert a value from miles per minute to millimeters per second (from mpm to mm/s) simply type the number of mpm to be converted to mm/s and then click on the 'convert' button.