Reach shows the potential number of people that might have come across your mentions. How this is calculated varies depending on the media type. The following is an explanation of how we calculate reach for each media type.
Online Articles: Based on daily visitor data from Alexa Reach*. Potential reach.
Blogs: Based on daily visitor data from Alexa Reach*. Potential reach.
Twitter: The number of followers of the specific Twitter account where the tweet was posted. Potential reach.
Facebook: The number of followers on the specific Facebook page where the post was published. Potential reach.
YouTube: The number of views for a video. Real reach.
Instagram: Reach is currently not available on Instagram due to restrictions in the Instagram API.
Forums: Based on daily visitor data from Alexa Reach, divided by 1000. Alexa Reach displays the number of site visitors on the start page of the forum, and since a forum has thousands of threads, we divide that number by estimating the proportion of users who can be assumed to visit a specific thread. Potential Reach.
*About Alexa Reach
Alexa is one of the most established tools for measuring reach. Alexa uses different factors to establish the number of visitors on a page and one of them is the traffic data from users that have their different plugins installed. You can read more about this here.