Newtons per square millimeter to inches of water conversion calculator shown above calculates how many inches of water are in 'X' newtons per square millimeter (where 'X' is the number of newtons per square millimeter to convert to inches of water). In order to convert a value from newtons per square millimeter to inches of water (from N/mm² to inH2O) just type the number of N/mm² to be converted to inH2O and then click on the 'convert' button.