The present invention relates to a method for determining the compressive tensile force acting on a fuel cell stack due to at least one tensioning element. Thereby, the compressive tensile force is the overall tensile force compressing the fuel cell stack. This is determined according to the invention by means of acoustic measurements on vibratable sections of the tensioning elements. The subject matter of the invention also includes a data processing program for carrying out the method according to the invention along with the use of a smartphone for carrying out the method according to the invention.