In general, this specification relates to content presentation. One aspect of the subject matter described in this specification can be embodied in methods that include the actions of presenting one or more content items to a user, each content item being associated with a conversion location; logging an identifier for each of the one or more content items presented to the user; receiving a location and user identifier from the user; using the user identifier to identify the one or more content items presented to the user and comparing, using one or more processors, the location to the conversion location of the one or more content items presented to the user; and logging a conversion for a particular presented content item having a conversion location matching the received location. Other embodiments of this aspect include corresponding systems, apparatus, and computer program products.