Viewability is a measure of whether an ad had a chance to be seen by a user.

## Measure / Calculate with Active View

Active View is a proprietary ad viewability solution that implements all of the standards established by the Interactive Advertising Bureau (IAB).

It calculate an Active View score

Active View breaks down viewability into the following buckets:

• Eligible impressions - An impression is considered eligible if it's successfully communicated with the ad server.
• Measurable impressions - From the group of eligible impressions, we determine how many are measurable — meaning that they're eligible to be measured by Active View technology.
• Viewable impressions - Viewable impressions, culled from the measurable impressions group, are the remaining impressions considered viewable based on MRC standards.

Which means among the total impressions served:

• a percentage are considered eligible impressions. Of those eligible impressions:
• a percentage are considered measurable impressions. And of the measurable impressions,

• Using the reporting capabilities of Google Ad Manager’s Active View, you can quickly determine whether the impressions you’re serving are viewable by your users.

## Metrics

### Active View % viewable impressions

the most important metric is Active View % viewable impressions, defined as the percentage of viewable impressions out of all measurable impressions. That calculation looks like:

$$\text{Active View % viewable impressions} = \frac{\text{viewable impressions}}{\text{measurable impressions}} × 100$$

### % Measurable

% Measurable shows the percentage of impressions that were measurable with Active View, out of the total number of Active View eligible impressions. In other words, this reveals how much of your inventory is accessible for Active View to record data.

### % Viewable

% Viewable shows the percentage of viewable impressions out of all measurable impressions.

It's recommended that you optimize your site to make sure that the % Viewable metric is as high as possible.