Gigapascals to inches of water converter on this page calculates how many inches of water are in 'X' gigapascals (where 'X' is the number of gigapascals to convert to inches of water). In order to convert a value from gigapascals to inches of water (from GPa to inH2O) type the number of GPa to be converted to inH2O and then click on the 'convert' button.