This article investigates the possibility that e-journal collections can reach a maximum size that satisfies long-term patron needs without further significant expansion. The study included collection and usage data taken from 2000 to 2013. In terms of the e-journal collection, the occurrence of a maximal mass appears to be very real. The e-journal collection has well-defined critical and maximal masses. The maximal mass of e-journals stands at approximately 25,000 unique titles.