Purpose: This paper aims to investigate the relationship between hybrid classes (where a per cent of the class meetings are online) and transportation-related CO[subscript 2] emissions at a commuter campus similar to San José State University (SJSU). Design/methodology/approach: A computer model was developed to calculate the number of trips to campus for a student body similar to SJSU. Different scenarios considered the theoretical effectiveness of implementing a hybrid course system to reduce CO[subscript 2] emissions. Findings: Increases in hybrid courses resulted in decreased student trips to campus and associated CO[subscript 2] emissions. The utility of such a relationship is demonstrated through a case study where the required increase in online class meetings needed to eliminate the need for an overflow parking lot is studied. Finally, preferential scheduling of online meetings can further reduce trips to campus. Research limitations/implications: A limitation of the model is that student schedules are random. Future research could use actual student schedules to better model how online course delivery will affect trips to campus. Practical implications: As today's universities struggle with financial pressure, online course delivery is being offered as a way to cope. This analysis provides an additional metric to evaluate online courses and includes other potential financial savings. Social implications: Transportation contributes to local air pollution and emissions of heat-trapping gases. As universities move toward more sustainable behaviors, reducing automobile trips to campus can be seen as a priority. Originality/value: To the authors' knowledge, this is the first attempt to model the relationship between hybrid courses and CO[subscript 2] emissions at an urban university. This information will be valuable to the SJSU community, as well as many other institutions.