Feet per second to nautical miles per day conversion calculator above calculates how many nautical miles per day are in 'X' feet per second (where 'X' is the number of feet per second to convert to nautical miles per day). In order to convert a value from feet per second to nautical miles per day (from ft/s to nmi/d) simply type the number of ft/s to be converted to nmi/d and then click on the 'convert' button.