One or more techniques and/or systems are provided for determining a user work schedule. A user may seldom update actual work hours, such as within a calendar, to reflect an actual schedule of the user, which may result in erroneous information being exposed to services that may notify other users as to when the user is inside or outside work hours. Accordingly, user signals (e.g., a current device location, execution of a work-related app, access to a work VPN, participation in a conference call from home, etc.) may be evaluated to generate a set of user activity patterns that may be indicative of recurring work patterns of the user. A user work schedule for the user may be determined based upon the set of user activity patterns. The user work schedule may be used to modify user interfaces (e.g., a conferencing website, a phone app, etc.) exposed to other users.