Percentage of ferrite and ferrite number was measured or calculated on a set of 22 samples coming from welding trials related to welding procedure specifications or all weld metal characterizations. Various welding processes, welding preparations and parameters were tested to cover a broad range of ferrite contents. Metallographic manual point counting, magnetic measurements using a magnetometer with axial extraction technique and X-ray diffraction had been performed in order to measure the percentage of ferrite. The ferrite number was given using the WRC diagram and magnetic permeability measurements by induction using a Feritscope apparatus. All these results were then discussed focussing on the accuracy and reliability of the different techniques. Ultimately, some recommendations are suggested for controlling the amount of ferrite during fabrication. A correspondence curve between the two scales is proposed.