Google Ads Competitive Metrics: Impression Share, Lost IS, and Auction Insights
What Competitive Metrics Are and Why They Matter
Competitive metrics are a distinct layer of Google Ads reporting. While basic metrics such as impressions, clicks, cost, and conversions describe what actually happened in your campaigns, competitive metrics describe the gap between what happened and what could have happened.
They answer a specific question: of all the auctions you were eligible to enter, how many did you actually show up in? And when you did not show up, why not?
This distinction matters because a campaign can look perfectly healthy in isolation, with a good CTR, a solid conversion rate, and a CPA within target, while still missing a large share of its available market. Competitive metrics are the only way to see that gap.
The group breaks into three subgroups: Impression Share metrics, Lost Impression Share metrics, and Prominence metrics.
Core idea: standard metrics tell you what happened. Competitive metrics tell you how much more was available and why you did or did not capture it.
Search Competitive Metrics
Search Impression Share
UI name: Search impr. share
API field: metrics.search_impression_share
Search Impression Share is the baseline market coverage metric for the Search network. It tells you what fraction of eligible search auctions your ads actually appeared in. A Search IS of 45% means 55% of users who searched your keywords, in your geo, during your ad schedule, did not see your ad.
That is not automatically a problem. Many accounts deliberately run at less than 100% Impression Share because the marginal cost of capturing the remaining share is not worth it at the target CPA or ROAS. But it is always the right starting point for a coverage discussion.
Campaign type availability: Search, Shopping, and Performance Max at campaign level only. It is not available for Display, Video, App, or Demand Gen.
API resource availability: selectable from campaign, ad_group, and keyword_view. It is not available from ad_group_ad or asset-level resources.
Segment support: available with device segmentation. Network segmentation is supported, but Search Partners are excluded from all impression share calculations regardless.
Search Lost Impression Share, Budget
UI name: Search lost IS (budget)
API field: metrics.search_budget_lost_impression_share
This metric estimates the share of eligible impressions you lost because your campaign budget ran out before the end of the day. A value of 0.22 means roughly 22% of your potential impressions were lost to budget exhaustion.
The word estimate matters. Google models the number based on historical traffic patterns and budget pacing behavior. It is directionally reliable, but not perfectly precise.
The practical read is straightforward. If Search Lost IS (budget) is high and your CPA or ROAS is within target, that is a direct argument for increasing the budget. If performance metrics are already strained, the better move is usually to tighten targeting before expanding budget.
Diagnostic rule: Search IS + Search Lost IS (Budget) + Search Lost IS (Rank) ≈ 100%. They describe almost the full eligible impression pool, with small rounding differences.
Search Lost Impression Share, Rank
UI name: Search lost IS (rank)
API field: metrics.search_rank_lost_impression_share
This estimates impressions lost because your Ad Rank was not high enough to show. Ad Rank is affected by bid, Quality Score, the expected impact of your ad assets, and the context of each specific auction. Losing to rank means you are losing in the auction mechanics, not simply running out of money.
The key split is between a bid problem and a quality problem. If Lost IS (rank) is high, either your bid is too low for the competitive environment, or your Quality Score is too low for your current bid level.
Case 1: low bid, reasonable Quality Score
- Raise bids
- Or move to a bidding strategy that can optimize bids dynamically
Case 2: low Quality Score, reasonable bid
- Improve expected CTR, ad relevance, and landing page quality
- This is often more efficient than forcing the issue with higher bids
Case 3: raising bids on low-QS keywords
- Usually an expensive short-term fix
- It does not solve the underlying problem
Search Absolute Top Impression Share
UI name: Search abs. top IS
API field: metrics.search_absolute_top_impression_share
Formula: impressions in position #1 above organic / eligible impressions for that position
This measures how often you appear in the very first ad position above organic results relative to how often you were eligible to appear there. It is the metric used as the target in the Target Impression Share bidding strategy when the goal is to dominate the top position.
The use case is mainly brand campaigns and high-intent commercial terms where being first matters. For branded keywords, you generally want this number to be high. For non-brand campaigns, the business case depends on the economics of the category.
Availability: Search and Shopping only. Not available for Performance Max.
Search Top Impression Share
UI name: Search top IS
API field: metrics.search_top_impression_share
Formula: impressions anywhere above organic / eligible impressions for those positions
In Google terminology, top means any position above the organic results. Search Top IS measures your share of those premium positions relative to what was available to you.
Comparing Search Top IS and Search Absolute Top IS together gives you a positioning picture. If Top IS is 60% but Abs. Top IS is 15%, you are frequently in the top block but rarely first.
Availability: Search and Shopping. Not available for Performance Max.
Search Lost Absolute Top IS, Budget and Rank
API fields: metrics.search_budget_lost_absolute_top_impression_share and metrics.search_rank_lost_absolute_top_impression_share
These apply the same lost impression share logic, budget versus rank, but specifically to the first ad position above organic. They are useful when position #1 is a strategic requirement, not just a preference.
Availability: Search only. Not available for Shopping or Performance Max.
Search Click Share
UI name: Search click share
API field: metrics.search_click_share
Formula: your clicks / estimated maximum clicks available
Click Share is more demanding than Impression Share. Google estimates not just how many impressions were available, but how many clicks you could have received if your ads were always shown in their best possible position. It accounts for expected CTR at different positions.
Click Share can be meaningfully lower than Impression Share even if you are winning many auctions. A large gap between IS and Click Share points to a CTR problem. You are showing, but not compelling enough to get the click.
Availability: Search and Shopping only.
Display Competitive Metrics
The Display Network has its own set of impression share metrics, structurally analogous to the Search versions. In practice, they are used less frequently for optimization because competitive dynamics in Display are harder to interpret. The eligible impression pool is driven by audience and contextual targeting rather than explicit keyword matches.
Content Impression Share and Lost IS
API fields: metrics.content_impression_share, metrics.content_budget_lost_impression_share, and metrics.content_rank_lost_impression_share
Content Impression Share measures your share of available Display impressions relative to your targeting settings. Lost IS (budget) and Lost IS (rank) split the losses the same way as in Search: budget exhaustion versus insufficient ad rank.
Availability: Display campaigns only. Not available for Performance Max, Video, App, or Search-type campaigns.
Prominence Metrics
Prominence metrics are frequently confused with impression share metrics, but they measure something different. Impression share is competitive: your share of the available market. Prominence metrics are positional: of the impressions you actually won, where did they show up?
Absolute Top Impression Rate
UI name: Impr. (Abs. Top) %
API field: metrics.absolute_top_impression_percentage
Formula: impressions in position #1 / total impressions
This is the share of your own impressions that landed in the absolute top position. If you had 10,000 impressions and 2,800 of them were in position #1, your Absolute Top Impression Rate is 28%.
Important nuance: Google explicitly advises against using this metric to set bids. When you raise bids, you often enter more competitive auctions where you may land in lower positions, so Absolute Top % can fall even as spend rises. Use Search Abs. Top IS for bid targeting instead.
Availability: Search, Shopping, and Performance Max at campaign level.
Top Impression Rate
UI name: Impr. (Top) %
API field: metrics.top_impression_percentage
Formula: impressions in the top block / total impressions
This shows the share of your impressions that appeared anywhere above the organic results, not just in position #1. The same caveat applies here as with Absolute Top Impression Rate: do not use this as a bid target. Use Search Top IS instead.
Availability: Search, Shopping, and Performance Max at campaign level.
Performance Max: A Special Case
Performance Max deserves its own section because competitive metric support is much more limited than in Search or Shopping, and the limitations are architectural rather than temporary.
PMax runs across multiple networks simultaneously, including Search, Display, YouTube, Gmail, Maps, and Discover. There is no single auction pool against which Google can calculate one unified impression share. Google does calculate Search-based competitive metrics for PMax, but only at the campaign level.
Available for Performance Max at campaign level:
metrics.search_impression_sharemetrics.search_budget_lost_impression_sharemetrics.search_rank_lost_impression_sharemetrics.absolute_top_impression_percentagemetrics.top_impression_percentage
Not available for Performance Max at any level:
metrics.search_absolute_top_impression_sharemetrics.search_top_impression_sharemetrics.search_click_share- Any competitive metric at asset group level or below
What this means in practice:
- If you need granular competitive visibility, PMax remains a reporting blind spot
- The channel-level performance report adds some visibility, but not channel-level impression share
Auction Insights: Competitor-Level Data
Impression Share and Lost IS metrics tell you about your own performance in aggregate. Auction Insights takes that one step further by showing your performance relative to specific competitors that appeared in the same auctions.
Auction Insights is not available through standard GAQL metrics.* fields. It is a separate reporting surface, accessible in the interface through the Auction Insights tab and through a separate API resource rather than the standard metrics query.
For Search Campaigns
Auction Insights shows six statistics per competitor:
- Impression share, their share of eligible impressions in your shared auctions
- Overlap rate, how often their ad and your ad appeared in the same auction
- Outranking share, how often your ad ranked above theirs or appeared when theirs did not
- Position above rate, how often their ad ranked above yours when both appeared
- Top of page rate, how often their ad appeared in the top block
- Absolute top of page rate, how often their ad appeared in position #1
For Shopping and Performance Max
For Shopping, Auction Insights is limited to impression share, overlap rate, and outranking share. Position-based metrics are not available.
For Performance Max, Auction Insights is available at campaign level. PMax impression data across the Search network is segmented into Search and Shopping categories inside the Auction Insights report.
Availability requirement: Auction Insights only populates when there is sufficient auction activity. For short date ranges or low-volume keywords, you may see no data at all.
Reading Competitive Metrics as a Diagnostic System
Competitive metrics are most useful as a system, not in isolation. The combination of Impression Share, Lost IS (budget), and Lost IS (rank) tells a specific story about what is limiting your campaign, and each story requires a different response.
| Search IS | Lost IS (Budget) | Lost IS (Rank) | Diagnosis and action |
|---|---|---|---|
| Low | High | Low | Budget-constrained. If performance metrics are good, increase budget to capture more of the available market. |
| Low | Low | High | Quality or bid issue. More budget will not help. Improve Quality Score components or raise bids relative to the competitive level. |
| Moderate | Moderate | Moderate | Mixed constraints. Evaluate which loss type is larger. Quality and budget issues often coexist, so fixing quality first is usually more efficient. |
| Good IS, but Click Share much lower | Low | Low | CTR problem. You are winning auctions but not getting the click. Focus on ad copy, headline relevance, and assets. |
| IS drops suddenly with no budget change | Stable | Spikes | Competitive pressure increased or Quality Score dropped. Check for ad disapprovals, QS changes, or new competitors in Auction Insights. |
Metric Availability by Campaign Type
In the table below, Campaign level only for Performance Max means the metric is available when querying the campaign resource, but not at ad group, asset group, or lower levels.
| Metric / API field | Search | Shopping | PMax | Display | Video | App | Demand Gen |
|---|---|---|---|---|---|---|---|
Search Impression Share metrics.search_impression_share |
Yes | Yes | Campaign level only | No | No | No | No |
Search Lost IS (Budget) metrics.search_budget_lost_impression_share |
Yes | Yes | Campaign level only | No | No | No | No |
Search Lost IS (Rank) metrics.search_rank_lost_impression_share |
Yes | Yes | Campaign level only | No | No | No | No |
Search Abs. Top IS metrics.search_absolute_top_impression_share |
Yes | Yes | No | No | No | No | No |
Search Top IS metrics.search_top_impression_share |
Yes | Yes | No | No | No | No | No |
Lost Abs. Top IS (Budget) metrics.search_budget_lost_absolute_top_impression_share |
Yes | No | No | No | No | No | No |
Lost Abs. Top IS (Rank) metrics.search_rank_lost_absolute_top_impression_share |
Yes | No | No | No | No | No | No |
Search Click Share metrics.search_click_share |
Yes | Yes | No | No | No | No | No |
Content IS metrics.content_impression_share |
No | No | No | Yes | No | No | No |
Content Lost IS (Budget) metrics.content_budget_lost_impression_share |
No | No | No | Yes | No | No | No |
Content Lost IS (Rank) metrics.content_rank_lost_impression_share |
No | No | No | Yes | No | No | No |
Abs. Top Impression Rate metrics.absolute_top_impression_percentage |
Yes | Yes | Campaign level only | No | No | No | No |
Top Impression Rate metrics.top_impression_percentage |
Yes | Yes | Campaign level only | No | No | No | No |
Auction Insights (separate report, not metrics.*) |
Yes | Yes | Campaign level only | No | No | No | No |