What does Viewable Impression mean?

An ad impression occurs whenever an ad serving platform (such as DFP or OpenX) loads a display ad on a webpage. However, many impressions that are “served” are never seen by a visitor if they appear on a section of the site that requires users to scroll down from the initial load.

A viewable impression refers to an ad that is displayed in a viewer’s screen for a specified amount of time. That doesn’t necessarily mean that it is viewed–some banner blind visitors completely tune out ads–but that it was at least viewable.

Ads that are above-the-fold are visible as soon as a webpage loads, and are therefore viewable impressions (assuming that the visitor doesn’t scroll past them before the minimum viewable time is met).

Ads that appear below-the-fold will typically load along with the rest of the webpage. If, however, the visitor doesn’t scroll down to the portion of the page where these ads are located, these ads would never be viewable.

All Recipes ExampleViewable Impression Example

Let’s assume that the adjacent webpage, from AllRecipes.com, is loaded but that the visitor never scrolls down. As a result, only the content above the black horizontal like is ever visible.

When this page load occurs, seven ad impressions would be recorded. However, only  two viewable impressions would occur: the 728×90 leaderboard and the 300×250 medium rectangle at the top of the page.

All of the ad impressions below the fold would only be considered to be “viewable” if the visitor scrolls down and puts them into the screen for a minimum amount of time.


How to improve ad viewability? 

There are many ways to improve ad viewability, and these are includes: 

  • Optimized for speed

According to Google that mobile sites that loaded within 5 seconds versus 19 seconds, were observed to have 25% higher viewability. If a web page takes a long time to load, it will reduce the viewability since the visitor would likely leave the web. 

  • Engaging content

The most obvious way to make the users to stay on the web page is to create engaging content. The more the users find the content engaging, the longer they will stay on the page, and it will increase the viewability

  • Ad position and type

Choose the ad units that have greater visibility. Also, try to implement responsive ad units that resize according to the viewport, so that ad is compatible with all device types.

  • Good design

Publisher should ensure that their web page has good design and clean layout. Shorter content tends to yield higher viewability, but if you have longer-form content, make sure there is a clear visual hierarchy with adequate proportions. 

Other Applications

The concept of a viewable impression can impact various metrics as well:

  • Viewable CTR: This term refers to the click-thru rate only on viewable impressions. This would be calculated as: total clicks / viewable ad impressions.


The concept of a viewable impression will likely become increasingly important for sites that monetize through direct ad sales.

Many advertisers and agencies are making a push to pay only for viewable impressions during CPM-based campaigns. As this becomes the common practice, it will reduce the number of impressions for which publishers are allowed to bill. This could obviously have an adverse impact on revenue, especially for sites that sell a large amount of below-the-fold under a CPM model.

If you are currently monetizing a large number of non-viewable impressions via CPM-based ad campaigns, you may need to begin considering alternatives for these units. In a few years, it is very possible that almost all advertisers will only pay for viewable impressions. This will likely set off a number of changes in the display ad industry, including a general increase of rates.


What is a viewable impression?

Viewable impressions are a term used for online advertising metrics refers to an ad delivered onto a web page in a place that could be seen by the user.

How are viewable impressions measured?

There are a few different standards of viewability but the main one to focus is a display ad must have 50% of its pixel (or more) visible for at least one continuous second within the frame of a browser.

Why are viewable impressions important?

Viewability data can help publishers increase the long term value of their display inventory. Advertisers are asking to buy viewable impressions, and publishers with the most viewable inventory will be in the best position to earn more revenue.