This article explores how the shift from print to electronic calendars materializes and exacerbates a distinctively quantitative, “spreadsheet” orientation to time. Drawing on interviews with engineers, I argue that calendaring systems are emblematic of a larger design rationale in Silicon Valley to mechanize human thought and action in order to make them more efficient and reliable. The belief that technology can be profitably employed to control and manage time has a long history and continues to animate contemporary sociotechnical imaginaries of (...) what automation will deliver. In the current moment we live in the age of the algorithm and machine learning, so it is no wonder, then, that the contemporary design of digital calendars is driven by a vision of intelligent time management. As I go on to show in the second part of the article, this vision is increasingly realized in the form of intelligent digital assistants whose tracking capacities and behavioral algorithms aim to solve life’s existential problem—how best to organize the time of our lives. This article contributes to STS scholarship on the role of technological artifacts in generating new temporalities that shape people’s perception of time, how they act in the world, and how they understand themselves. (shrink)