Calibration of a penetrometer is an important step in the metrological confirmation of cone penetration testing. This paper summarises experience of Fugro’s calibration laboratory based in The Netherlands. This laboratory performs calibrations for about 3000 cone penetrometers used worldwide. The calibration laboratory is accredited to ISO/IEC 17025:2005 “general requirements for the competence of testing and calibration laboratories”. This accreditation status is unique for cone penetration test equipment and implies rigorous quality standards.