PINTEREST INC

The numbers for our key metrics, which include our monthly active users ("MAUs") and average revenue per user ("ARPU"), are calculated using internal company data based on the activity of user accounts. We define an MAU as an authenticated Pinterest user who visits our website, opens our mobile application or interacts with Pinterest through one of our browser or site extensions, such as the Save button, at least once during the 30-day period ending on the date of measurement. The number of MAUs does not include Shuffles users unless they would otherwise qualify as MAUs. Unless otherwise indicated, we present MAUs based on the number of MAUs measured on the last day of the current period. We measure monetization of our platform through our ARPU metric. We define ARPU as our total revenue in a given geography during a period divided by the average of the number of MAUs in that geography during the period. We calculate average MAUs based on the average of the number of MAUs measured on the last day of the current period and the last day prior to the beginning of the current period. We calculate ARPU by geography based on our estimate of the geography in which revenue-generating activities occur. We use these metrics to assess the growth and health of the overall business and believe that MAUs and ARPU best reflect our ability to attract, retain, engage and monetize our users, and thereby drive revenue. While these numbers are based on what we believe to be reasonable estimates of our user base for the applicable period of measurement, there are inherent challenges in measuring usage of our products across large online and mobile populations around the world. In addition, we are continually seeking to improve our estimates of our user base, and such estimates may change due to improvements or changes in technology or our methodology.