Microbes power biogeochemical cycles and significantly alter host fitness. Yet the way we study microbes can be detached from the quantitative assessments needed to link community properties to larger scale processes or ecological theory. Increasingly microbial communities are viewed through lenses of ordinations, relative abundances, sequences counts, and treatment effects. Likewise, many measurements are in units that are difficult to compare across studies (e.g. community similarity), or describe a proxy (e.g. lipid biomarker signatures) that is difficult to scale to other relevant variables. Complementing relative approaches with quantitative assessments will increase the impact and extrapolation potential of microbial studies. This session aims to highlight existing efforts – and motivate future studies – that ground microbial research in absolute, comparable numbers for greater impact and broader engagement in the field. Speakers will demonstrate diverse ways that they have, or plan to, ‘put a number on it’ across various study systems. These brief research descriptions may describe mathematical and laboratory methods (both new and old) that aid in quantification, but may also highlight simple auxiliary measurements or calculations that have served to effectively contextualize results. In this session, we hope to assess methodological and conceptual gaps in microbial ecology and provide concrete ways to increase the impact of microbial research using quantitative approaches.