The evidence for economic impact of molecular modelling of chemicals and materials is investigated, including the mechanisms by which impact is achieved and how it is measured. The impact pathway is followed from the fundamental theories via the users of software to the researchers that utilise the results and to new, engineered products. While a quantification of the impact of one methodology is very difficult, it has been possible to consider measures of impact at each stage along the above mentioned pathway. This included publications, patents, the growth of the communities of modelling authors, users, and consumers of the technology and the ensuing software industry. Quantification of R&D process improvements due to modelling could be related to key metrics of value creation. On a macroeconomic level, it was attempted to estimate the contributions that modelling makes as a proportion of chemistry research as well as high performance computing.