The rise of smartphones has transformed search behavior, with almost two-thirds of the US population expected to search on smartphones this year—a phenomenon that has changed how search results look and allowed users to start searching with their voice or an image.

Among the many digital activities we have tracked over the years, search is second in penetration only to email. We estimate that 85.4% of US internet users, or 242.5 million people, executed searches monthly in 2019. Those figures will rise slightly to 85.6% and 246.4 million, respectively, by the end of this year.

The vast majority are conducting many of these searches on smartphones. We estimate that more than nine in 10 smartphone users in the US searched on those devices in 2019, amounting to 211.5 million people, or 64.0% of the population. (Note that we do not provide estimates of search users on desktop and laptop PCs, a group that overlaps with smartphone search users.)

These searches on smartphones and other mobile devices add up to a mountain of mobile search impressions, including for search ads.

Marketing technology provider Kenshoo reported that more than 70% of its clients’ US search ad impressions, as well as clicks, occurred on mobile devices in Q3 2019. However, mobile’s share of ad spending just passed the 50% mark in Q2 2019 due to the historically lower prices for mobile search ads compared with desktop ads.

Merkle, another performance agency focused on search, social and ecommerce channel advertising, also reported that 69% of its clients’ US search ad clicks on Google and Microsoft search ad platforms came from mobile devices in Q3 2019, with almost all of that total coming from mobile phones (64%). Clicks from tablets have stagnated in recent years, but mobile phones have accounted for a steadily increasing share.

Similar to Kenshoo, Merkle reported that mobile’s portion of search ad spending lagged its impression share. Paid search ads run on smartphones and tablets accounted for just 41% of search ad spending in Q3 2019 because performance lagged on mobile phones compared with desktop. For nonbranded paid search placements, for example, revenues per click on mobile were just 34% as high as on desktop, and costs-per-click (CPCs) were 47% as high.

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