Book excerpt: The modelling tools for soils and rocks require more and more specific parameters not always available from the standard or usual survey campaigns, this generally for reasons of delay or costs. The use of correlations to solve the gap between available parameters and the required ones is a common practice. Many of them exist but are spread throughout numerous papers or books. The aim of this formulary is to provide a large synthesis of the existing correlations accumulated by the authors during more than 40 years academic and consulting careers.