What is Viewability?

Viewability or viewable impressions is an advertising metric used to define impressions which can actually be seen by users, instead of simply recorded by publisher’s automated systems.

The most common example of viewability are ads loaded at the bottom of a page. If a user doesn’t scroll down, they won’t view it. However, it will be automatically recorded as an impression. With viewability as a factor, this impression wouldn’t be determined as viewable (and as such, wouldn’t be charged).

There is no industry standard that determines whether an ad is viewable. The IAB defines viewable impression as an impression that is at least 50% visible for at least 1 second. The Media Rating Council claims ads are viewable if 50% of desktop display ads are displayed for at least one second, desktop video ads have at least 50% in view for at least 2 seconds, and larger desktop units have at least 30% in view for at least 1 second.

According to research, over 56% of ads aren’t viewable to users, but a vast majority of them are still charged to advertisers. Viewability allows advertisers to more accurately assess and determine the success of their ad campaigns, as they can be sure that all of the charged impressions have actually been viewed by users.