Device for calibration of a field transmitter comprising a shaped body on which there are disposed first means for sensing magnetic fields the activation of which allows calibration of a first measurement parameter of the transmitter, second means for sensing magnetic fields the activation of which allows calibration of a second measurement parameter of the transmitter, magnetic actuation means suitable to activate said first and second means for sensing magnetic fields. Said shaped body is configured so that it can be removably connected to the transmitter on the external surface of the enclosure thereof.