Based on a new policy update found in a blog post, which was announced on Tuesday, AdSense publishers are able to now include 300×250 ad units above the fold on their mobile websites.
John Brown, the head of publisher policy communications at Google explained in the blog post:
After careful review, we’ve determined that when 300×250 ads are implemented above the fold in a user-friendly way, the ads do not annoy, distract, or result in ad performance issues.
If you are a publisher who is featuring the ad unit above the fold on mobile, you’ll be warned to still have site content clearly shown in view to avoid accidental ad click.
Google’s own research showed that a 300×250 ad unit placed below the fold has a viewability rate of about 50 percent. This ad size had the lowest viewability rate at 41 percent of any standard ad size Google measured. By letting this popular ad unit appear above the fold on mobile, there will be the obvious effect of increasing viewability rates to around 70 percent per the study. So this basically means higher RPM potential for publishers, as well as Google itself.