Liquid Composite Moulding processes are considered as promising and effective to manufacture structure composite parts reinforced with synthetic and natural fabrics. The main novelty of this work is the estimation of capillary pressure (Pcap) for both fabrics at different fibre volume fractions (Vf) and with different liquids. From the previous works, the Pcap was defined as the equivalence between Washburn’s equation and Darcy’s law while our novel model for the capillary wicking could predict very well the swelling behaviour of natural fabrics. The combination of our Pcap definition and our novel model was explored in this study. Linear trends, thresholds and extremums of Pcap at different conditions were found for the first time. These results are relevant to estimate the importance of capillary effects during Liquid Composite Moulding processes and extremely valuable for numerical models at the fibrous scale to predict voids formation.