Inches per hour to millimeters per second conversion calculator above calculates how many millimeters per second are in 'X' inches per hour (where 'X' is the number of inches per hour to convert to millimeters per second). In order to convert a value from inches per hour to millimeters per second (from in/h to mm/s) just type the number of in/h to be converted to mm/s and then click on the 'convert' button.