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