Gigapascals to pounds per square inch conversion calculator above calculates how many pounds per square inch are in 'X' gigapascals (where 'X' is the number of gigapascals to convert to pounds per square inch). In order to convert a value from gigapascals to pounds per square inch (from GPa to psi) type the number of GPa to be converted to psi and then click on the 'convert' button.