Unfilled impressions are ad requests for which Ad Manager was not able to serve a line item. Ad Manager Help describes unfilled impressions as a ‘red alert’ to lost revenue, but this can be misleading, as they can be equally indicative of set-up issues.
Genuine unfilled impressions can be expensive. Therefore, understanding when these impressions represent real lost opportunity vs when they are a reporting anomaly is a valuable skill to have.
Where do I find unfilled impressions?
The most obvious place that unfilled impressions are shown is in the demand comparison card on the Google Ad Manager home page.
This card shows Unfilled as a green line on the chart, allowing you to easily spot changes over the reported period. In the example below, you can see a steep increase in unfilled impressions, which is something that you would definitely want to investigate further.
To monitor unfilled impressions over a period other than the 7 day or 30 day options of the home page cards, you need to run a report.
Where is the yield report?
Unfilled impressions used to be reported in the DFP Yield Report and many out of date guides still suggest using this report to diagnose and fix unfilled impressions. The Yield report was deprecated in January 2019 and has now been replaced by the Demand comparison card pictured above.
How to run an unfilled impressions report
You can run an unfilled ad impressions report directly from the Demand comparison card. Clicking the “Show details” drop-down in the image above will open up a table of additional information. Clicking the word “Unfilled” in this table runs a report showing unfilled impressions by ad unit for the period shown.
The same report can, of course, also be run by building your own query under Reports > Queries . This way you can even schedule the report to run periodically and have the results sent to you by email.
What causes an unfilled ad impression?
There are two common root causes of unfilled impressions in Google Ad Manager. The first is that Ad Manager attempted to display an ad but did not have an eligible line item. The second is that an ad unit was defined, but never displayed.
The first of these is a genuine missed opportunity, the second will cause unfilled impressions to be reported. This can cause problems, but is not immediately lost revenue in the same way as when Ad Manager is not able to show an ad for a true impression.
Fixing unfilled ad impressions
Fixing genuine unfilled impressions is a case of ensuring that you have a line item that can display in all circumstances. There are a number of reasons why this might not be the case, even when you think you should have all bases covered. Common ones include:
- Not targeting all ad unit sizes: Responsive set-up, in particular, may be calling units that have not been accounted for. Running a report on unfilled impressions by request size can identify this type of issue.
- Not enough demand to meet supply: If you are requesting ads faster than your demand sources can supply them, this will cause unfilled impressions. This is mostly a risk in situations where there are a high number of requests being made (high traffic and multiple ad units) and demand partners with limited supply. This can be resolved by adding high fill partners such as Ad Exchange.
- Poor viewability: Many demand partners have minimum viewability requirements. Ad Exchange will also lazy load ads and only display them when they will be viewed. This can result in unfilled impressions into low viewability units, or units that are defined without ever making it into view.
- No “catch all” line item: If every line item has targeting criteria that need to be met, then there may be situations where impressions slip through and go unfilled. Having a low priority line item that can serve when there is no higher valued line will resolve this.
- Rate limiting: If all lines are limited to a maximum number of impressions per user, you can be left without an eligible line item on high-depth visits. This can be resolved by ensuring that your “catch all” line has no rate limits.
Fixing falsely reported unfilled impressions
Google Ad Manager code exists in two parts: The units are defined in the header of the page and then called in-line in the body. If units are defined in the header but never called, then the impression is unfilled. This is a common issue on sites where the same ad unit definitions are used across multiple templates.
Although these unfilled impressions do not represent immediately lost revenue, they can still be problematic. Defining units that are not called can bring down your viewability, trigger invalid traffic warnings and mess with reporting.
Fixing the issue requires that unused ad unit definitions are removed from pages. One way to find these is to run a report of unfilled impressions by ad unit then look for places that those units are defined but not displayed. Another way is to view the site using publisher console looking for this same issue.
Unfilled ad impressions are definitely worth monitoring for, as any significant amount of them is problematic. Genuine unfilled ad impressions (ad units that are displayed without an impression) are the most immediately problematic, but also the easiest to fix.
Monitoring of issues such as unfilled impressions is just one of the regular tasks that OKO manage for publishers as part of our Website Monetization service. If you would like an expert team dedicated to protecting and growing your revenue, please get in touch.