At SMX West last week, one of the things Gary Illyes revealed is that the new mobile ranking boost will be determined on a page by page basis and will not be assigned to an entire based on how much of the site is mobile friendly.

When the change was first announced, it wasn’t certain if 100% of pages would need to be mobile friendly in order to get the ranking this, if a lesser percentage needed to be done, or if Google would look at each page individually and assign it a “mobile friendly” tags them.  And some webmasters were concerned if a single page on a site that wasn’t mobile friendly could render the entire site flagged as being mobile unfriendly.

Google will be determining whether a page on a site is mobile friendly on a page by page basis, and assigning a page as mobile friendly or not individually.  This means other non-mobile-friendly pages on a site can’t hurt those pages that are, when Google begins using mobile friendliness as a ranking factor.

This is good news for webmasters that may have elements on a small number of pages that could not be made mobile friendly for whatever reason, whether it was a flash video or some other elements that could not be scaled properly for mobile devices. There was concern that some websites might have to remove these non-mobile-friendly pages from a site entirely in order to be considered “mobile friendly” when mobile ranking signal comes into play with the Google search algorithm on April 21.

This also means that for webmasters that might be a one-person-show or with massive sites that take time to be fully updated to a mobile friendly site, those webmasters can focus first on pages that bring the most traffic or are the most popular and get those mobile friendly first, then work through updating the rest of the site.

You also won’t be stuck waiting for a “mobile update” when you do make those pages mobile friendly.  As soon as Google bot crawls them the next time and determines they are mobile friendly, they can get the boost from the mobile ranking signal.  At SMX West, Illyes said “As soon as we discover it is mobile friendly, on a URL by URL basis, it will be updated.”

If you want to learn all the mobile related information from Illyes at SMX, the full session was covered at Google’s Gary Illyes Q&A on Upcoming Mobile Ranking Change.