Methods, systems, and programs are presented for determining exposure rate. One method includes an operation for operation for receiving a request, from a client device, for a value of an exposure rate of a zone within a webpage, the request comprising at least one search parameter and information about a viewport of the presented webpage. A check is made to determine if the exposure rate has been previously calculated. When the exposure rate has not been previously calculated, a visibility height of the zone is calculated and stored in a memory. When the exposure rate has been calculated, the visibility height is retrieved from the memory. Recordings of members accessing the webpage are analyzed to determine when the visibility height of the zone is visible in member devices accessing the webpage. The exposure rate of the zone is calculated based on the determinations of visibility of the zone.