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