Abstract: The present invention provides a calibration adapter (1) for drilling resistance measuring devices (10) which have at least one drilling needle receptacle which is coupled to a drive, a drilling needle (15), a guide sleeve (12) with a drilling needle outlet opening and an apparatus for drilling resistance detection and output. The invention further provides a calibration apparatus and a drilling resistance measuring apparatus, and also a method for calibrated drilling resistance measurement. The calibration adapter (1) has a main body (3) which has a coupling apparatus (5) in order to be releasably fastened to the drilling resistance measuring device (10) upstream of the drilling needle outlet opening and a drilling needle passage channel (33) which extends through the main body (3) and which is designed in such a way that it is aligned with the drilling needle outlet opening in a fastening arrangement of the calibration adapter (1) to the drilling resistance measuring device (10).