We present an approach that aims to comprehensively account for scientists’ academic engagement and commercialization activities. While previous research has pointed to the economic and social impact of these activities, it has also been hampered by the difficulties of accurately quantifying them. Our approach complements university administrative records with data retrieved from external sources and surveys to quantify academic consulting, patenting, and academic entrepreneurship. This allows us to accurately account for ‘independent’ activity, i.e., academic engagement and commercialization outside the formal university channels and often not recorded by universities. We illustrate this approach with data for 10,000 scientists at Imperial College London. Results indicate that conventional approaches systematically underestimate the extent of academic scientists’ impact-relevant activities by not accounting for independent activities. However, with the exception of consulting, we find no significant differences between individuals involved in supported (university-recorded) and independent activity, respectively. Our study contributes to work concerned with developing appropriate and accurate research metrics for demonstrating the public value of science.