Impression Share
Paid MediaAlso: IS · Search Impression Share · Display Impression Share
Quick definition
Impression Share is the percentage of eligible ad auctions in which your ad actually appeared. If your ads could have shown 1,000 times but only showed 600 times, your Impression Share is 60%. The gap between 100% and your actual share is split into two buckets: lost to budget and lost to rank.
Impression Share alone doesn't tell you whether to act. Check whether the loss is budget or rank, then weigh the cost of closing that gap against your target CPA or ROAS.
How it varies across Australia
Impression Share across Australian advertisers varies sharply by category competitiveness and budget concentration. High-competition verticals like insurance, finance and legal typically see strong players holding a meaningfully higher share than challengers, while less competitive categories often leave substantial share unclaimed.
See acquisition performance across Australian industries →The three numbers that matter
The share of eligible auctions where your ad actually showed.
Target depends on strategyShare you missed because your daily budget ran out before the day did.
Fix: increase budget or tighten targetingShare you missed because your Quality Score or bid was too low to win the auction.
Fix: improve Quality Score or raise bidsWhat it actually means
Impression Share tells you how much of the available auction you are actually participating in. Think of it like a shop that could be open for 100 customer visits but only greeted 60. The 40 missed visits matter, and the reason for them matters more.
Google breaks the lost share into two causes. Lost to budget means your ads stopped showing because you spent the day's allocation before the day ended. Lost to rank means your ads were eligible but the combination of your bid and Quality Score wasn't high enough to win the auction at that moment.
These two causes have different fixes. Budget loss responds to increasing spend or tightening targeting so you show for fewer but more valuable queries. Rank loss responds to improving your Quality Score through better ad relevance, landing page experience and expected click-through rate (CTR), or raising bids.
Impression Share pairs naturally with ROAS and CPA to give a more complete picture of search coverage. A campaign with a strong ROAS but low Impression Share is leaving qualified demand on the table. A campaign with high Impression Share but poor ROAS is buying reach it cannot make profitable. The relationship between the two is the real diagnostic.
Low Impression Share is a symptom. The diagnosis comes from which bucket ate it.
How to calculate it
Impression Share = Impressions received ÷ Eligible impressions × 100
Worked example. Your Search campaign received 6,200 impressions last week. Google reports your Lost IS (Budget) as 18% and Lost IS (Rank) as 16%. That means eligible impressions were approximately 6,200 ÷ (1 - 0.18 - 0.16) = 6,200 ÷ 0.66 = 9,394. Impression Share = 6,200 ÷ 9,394 × 100 = 66%.
The Australian context
Australian search volumes are smaller than equivalent US markets, which means eligible impressions are more concentrated and Impression Share figures can swing more dramatically week to week than they would in a larger market. A campaign that looks stable in a US account can read as volatile in an Australian account simply due to lower base volumes.
Australian advertisers in regulated categories like financial services and healthcare face additional eligibility restrictions that reduce the total eligible impression pool, sometimes making high Impression Share figures misleading about true market coverage. Always filter by approved ad formats and check eligibility reasons before drawing conclusions.
Where people get this wrong
Related terms
Common questions
What is a good Impression Share for a Google Ads campaign?
There is no universal target. For branded campaigns, above 90% is generally the floor. For non-branded campaigns, the right share is whatever maximises conversion volume at your target CPA or ROAS. Chasing 100% on competitive generic terms is usually expensive and rarely profitable.
How do I improve Impression Share lost to rank?
Improve Quality Score by tightening keyword-to-ad-to-landing-page relevance, or raise bids. Quality Score improvements tend to be more durable and cost-efficient than bid increases because they reduce your cost per auction win rather than just outspending the competition.
Why does my Impression Share fluctuate so much week to week?
Impression Share is sensitive to competitor behaviour, seasonal demand shifts and your own budget pacing. In smaller markets like Australia, lower base volumes amplify these fluctuations. Use four-week rolling averages for trend analysis rather than reading individual weeks in isolation.
Does Impression Share work the same way in Google Shopping and Display campaigns?
The concept is the same but the eligibility criteria differ. Shopping Impression Share is calculated against searches where your product was eligible to appear, which depends on product feed data quality and pricing. Display uses a reach-based calculation. The lost-to-budget and lost-to-rank split applies across all three.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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