Impression share

Impression share (IS) is the percentage of impressions your ads received compared to the total number of impressions they were eligible for. Eligibility is determined by your targeting settings, approval status, quality scores, and bids. If your ad was eligible for 10,000 impressions in a given period and appeared 7,000 times, your impression share is 70%.

The metric is primarily used in Google Ads and Microsoft Ads, where it is reported at the campaign, ad group, and keyword level. It answers a question that other metrics cannot: how much of the available market opportunity are you capturing, and how much are you leaving on the table?

Impression share is decomposed into two types of loss: lost impression share due to budget and lost impression share due to rank. Budget-limited impression share means your daily budget ran out before the day ended, so your ads stopped showing. Rank-limited impression share means your ad rank (a combination of bid and quality score) was too low to win the auction for some eligible queries.

This decomposition is what makes impression share actionable. A campaign losing 30% of impressions to budget tells you that increasing budget will capture more opportunity. A campaign losing 30% to rank tells you that improving quality score or increasing bids is the path to more impressions. Without impression share, you would see the same total impressions in both scenarios but have no way to diagnose the cause or the opportunity.

Google Ads estimates total eligible impressions using auction data, quality factors, and targeting settings. The estimate is not exact but is directionally reliable for decision-making.

Impression share is reported as a percentage at the campaign, ad group, and keyword level. At the keyword level, it tells you how effectively you are competing for specific search terms. At the campaign level, it gives an aggregate view of market coverage.

The two loss metrics decompose the gap between your actual impression share and 100%.

Impression share connects to campaign reach and revenue by determining how many potential impressions turn into actual ad displays. It decomposes into budget adequacy and ad competitiveness.

The tree shows that impression share is the first conversion point in the paid search funnel. Before a user can click your ad, the ad must appear. Impression share determines what fraction of eligible searches actually see your ad.

The decomposition into budget adequacy and ad rank competitiveness makes the optimisation path clear. If impression share is low due to budget, increasing spend is the direct solution. If it is low due to rank, improving quality score through better ad relevance, expected click-through rate, and landing page experience is more cost-effective than simply raising bids.

1. 1

   Increase budget for budget-limited campaigns

   If lost IS due to budget is significant, your ads are running out of budget before the day ends. Increase the daily budget or redistribute budget from lower-priority campaigns to capture the missed impressions.

2. 2

   Improve quality score to reduce rank loss

   Quality score is the most cost-effective lever for improving ad rank. Improve expected CTR through better ad copy, improve ad relevance by tightening keyword-to-ad alignment, and improve landing page experience through faster load times and relevant content.

3. 3

   Refine targeting to focus on winnable impressions

   Broad targeting dilutes impression share across too many queries. Tighten keyword match types, add negative keywords, and use audience targeting to focus budget on the searches and users most likely to convert.

4. 4

   Use ad extensions to boost ad rank

   Sitelinks, callouts, structured snippets, and other extensions improve ad rank without increasing bids. They also improve CTR, which feeds back into quality score over time.

5. 5

   Adjust bid strategies based on loss type

   If rank loss is concentrated at specific times of day or on mobile devices, use bid adjustments to compete more aggressively in those segments rather than raising bids across the board.