Definition: Viewability Rate [VR]

What is a Viewability Rate?

Viewability Rate is the percentage of ads that are actually seen by a user.

By this we mean, the viewability rate is the percentage of ad impressions that count as being viewed. A viewed impression is described as being at least 50% on screen for one second. For example, if a website has 10 ad impressions, of which five are counted as viewable, then the site will have a Viewability Rate of 50%.

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What does Viewability Rate mean?

Viewability Rate is a new advertising metric that defines how many ad impressions on a site are actually viewed by users. The standard definition is that any ad which is at least 50% on screen for one second counts as being viewed. This definition is still being debated, however.

This metric is important as the ad pricing model CPvM only pays out on viewable impressions.


Viewability Rate Formula

The Viewability Rate equation is:

Viewability Rate FormulaClick to enlarge

Viewability Rate = (Viewable Ad Impressions ÷ Ad Impressions) x 100


Note: “Measured ad impressions” are used in the above formula (as opposed to regular ad impressions). This is because viewability/verification vendors are unable to measure 100% of total ad impressions. As a result, measured ad impressions are always lower than ad impressions.

Measured ad impressions are simply the number of ad impressions measured by a company.


What it looks like

What a viewable ad impression looks likeClick to enlarge


Top Tip

Place your ads above the fold to make sure your ads are all viewable. This will help even for users who don’t scroll down.


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