Abstract: The invention relates to a system for calibrating and measuring the magnetizability of at least a part of a rail, for instance a rail for guiding means of transport. The system includes a magnetic field generator for generating a changing magnetic field transverse to a longitudinal direction of the rail. The magnetic field generator comprises a substantially saddle-shaped transmitter coil arranged to be placed partly around the rail. The system further includes an induction detector for measuring a transverse induction. The system may further include a magnetic field generator for generating a changing magnetic field in the longitudinal direction, an induction detector arranged for measuring a longitudinal induction, and a processing unit arranged for determining a reference induction, on the basis of the transverse induction, and determining a longitudinal mechanical stress in rail on the basis of the longitudinal induction and the reference induction.