Smartphones became powerful tools for interacting with information anytime and anyplace. This paper investigates mobile information supply by assessing smartphones as information channels. We apply concepts of information theory for estimating the amount of information that smartphones supply. We contribute a measure of mobile information supply and describe a large-scale study analyzing data from more than 790 participants. Our main ﬁndings are that our participants’ smartphones supply about 13 bytes of information per second and 1143 bytes per session. Further, within device sessions mobile information supply peaks at the beginning and the end. Our data also shows differences between sessions regarding the ratio of supplying old content vs. new content.