Search Impression Share for PPC: What You Need to Know

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Making a good impression is important in many aspects of life, from job interviews to client interactions to social encounters. In terms of paid search and Google Ads, making a good impression (and making as many of them as possible) is potentially the most important aspect of any successful PPC campaign. The metric used to measure that success is search impression share.

What Is Search Impression Share?

Search impression share is the number of times a paid search ad appeared on search results (Google or otherwise) divided by the number of times if could possibly have appeared. This metric shows if your campaigns are missing out on potential traffic and conversions due to a number of factors, namely budget and rank. Search impression share can also be viewed by an ad’s position on a search results page, either in the very top spot or in positions above the fold.

Search Impression Share and Budget

As it pertains to budget, campaigns would lose impression share if their budgets are not large enough to show at all possible times based on current targeting settings. For example, if you were running a campaign that could potentially get up to 10 impressions in a day at a $10 daily budget and the budget was spent for the day after only receiving 8 impressions, then your impression share would be 80% with 20% lost due to budget. In that scenario, your campaign could have potentially achieved 100% impression share with a 20% larger (in this case $12) daily budget.

While that example is fairly straightforward, the real-life application of search impression share for budget is not as simple. In reality, there is no definite way to know how many impressions a campaign would get in a day to make adjustments to budget on the fly. Rather, the best practice when it comes to using search impression share to determine ideal budget is to review the search impression share for a defined time period (at least a week but preferably a month or longer) and make the necessary adjustments.

Using our previous example of a $10 daily budget, we may find that we have lost 50% impression share due to budget during the past 30 days. This means that we would have needed to run the campaign at a minimum daily budget of $20 in order to have come close to reaching 100% impression share for those 30 days. While we cannot accurately project that increasing the daily budget to $20 will get us to 100% search impression share going forward, we can use this historical evidence to suggest that a budget increase could be beneficial in moving toward that goal. Alternatively, honing in settings such as ad schedule or location targeting and making adjustments to keywords can have the effect of lowering the number of possible impressions, which can in turn lessen the impression share lost due to budget without actually changing the budget itself.

Search Impression Share and Rank

In addition to budget, search impression share can also be lost as a result of ad rank. With rank, you would lose impression share if your ad rank was not high enough to show your ads for a given number of searches. Ad rank is determined by a combination of your max bid (including modifiers), the quality of your ads and landing pages, and the expected impact of extensions and other ad formats. Improving impression share lost due to ad rank comes down to bidding and quality score. You will need to bid more and improve on the factors that make up quality score in order to decrease the amount of impression share lost due to rank.

Search Impression Share and Ad Position

Prior to Fall 2019, paid advertisers relied on Google’s average position metric to report back to clients and optimize for the position their ads showed in Google search results like when you look for the place to add in the correct spot. Though widely used by paid advertisers and agencies alike, the average position metric was (by Google’s own admission) inherently flawed, as it did not accurately reflect where on the page the ads were actually showing. When Google did away with this metric in September 2019, they introduced two new metrics for search impression share to act as a functional and more accurate replacement for average position: search absolute top impression share and search top impression share.

Search top impression share is the number of impressions an ad showed in the top location of a search results page (above the organic listings) divided by the estimated number of impressions the ad was eligible to show in the top location. Similarly, search absolute top impression share is the same formula, only measured against showing in the number one position for the search results page. These two metrics effectively act as the best way to know if your ads made a “good” impression.

Best practices around these two metrics will largely depend on the goals of the client and campaign. A campaign being run on branded terms like company/client name, for example, would want to have a very high absolute top page impression share to ensure those ads are showing at the top of search results. This would also apply in cases where upstaging the competition is crucial to success. The downside of this strategy is that it can drive up costs and, as a result, begin to increase the amount of search impression share being lost due to budget.

For most other instances, however, the best practice would be to focus on getting a balance between a high search top impression share and a reasonable cost per click. This can be achieved by optimizing for previously mentioned factors that affect Ad Rank, as well as the use of bidding rules or automated bidding strategies that focus on impression share.


Search impression share for PPC is not only about making a good impression — it’s also about making the right impression, at the right time, and in the right position. For a field as competitive as law, getting the correct budgets and positioning through tools such as search impression share is paramount to achieving successful results from any paid search campaign. At PaperStreet, we know the law and website marketing, and we know how to get the most out of PPC for law firms. Contact us to find out how we can start growing your client base today.

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