The implementation of the BSIM-CMG parameter extraction procedure is presented and discussed, based on measurements. FinFETs with mask channel length from 45nm to 10μm were measured and their DC I-V data used for the extraction. We show an improved fitting of a wide range of channel lengths using a single set of model parameters. Measured devices with fin thickness of 10nm, 15nm and 20nm are studied and the variation of extracted parameters discussed. We propose improvements on the BSIM-CMG extraction procedure to obtain a fitting over a wide range of L_eff. The results present mean absolute percentage errors around 50% and 30%, which shows that a single set of model parameters is inadequate for a wide range of FinFET geometries.