Atmospheres (standard) to inches of water conversion calculator above calculates how many inches of water are in 'X' atmospheres (standard) (where 'X' is the number of atmospheres (standard) to convert to inches of water). In order to convert a value from atmospheres (standard) to inches of water (from atm to inH2O) simply type the number of atm to be converted to inH2O and then click on the 'convert' button.