TL;DR

Google defines impression share as impressions divided by estimated eligible impressions, counting auctions where the ad showed or was competitive enough to show; Search Partners are excluded.
Search lost IS (budget) is reported at campaign level only, while Search lost IS (rank) points to bids or ad quality; with impression share they roughly cover the eligible pool.
The Google Ads API reports Search impression share between 0.1 and 1, returning values below 10% as 0.0999 and lost impression share above 90% as 0.9001.
Google's auction insights report shows no data when your impression share is below 10%, and impression share metrics update within 1-2 days.
Target impression share bidding can aim for anywhere, top or absolute top placement; Google suggests it for brand terms and warns that a low max CPC limit blocks the goal.

Google Ads impression share is the percentage of impressions your ads actually received out of the total impressions Google estimates they were eligible to receive. If a Search campaign shows 40% impression share, your ads appeared in roughly four of every ten auctions where Google judged them eligible and competitive enough to show, and two companion columns tell you whether the other six were lost to budget or to Ad Rank.

That makes impression share one of the few numbers in an account that describes the demand you are not reaching, rather than the traffic you already paid for. It is also an estimate built on rules that are easy to misread. This guide covers how Google calculates it, how the Search and Display versions differ, what the budget and rank loss columns mean, how top and absolute top share work, where to find each column, and what to change when each one moves.

Google's formula is a simple ratio: impression share equals impressions divided by total eligible impressions. The numerator is a count you can see in any report. The denominator is not. Google estimates eligible impressions from your targeting settings, the approval status of your ads and their quality, and it looks at the auctions over the course of the day using internal data about you and the other advertisers in those same auctions.

The detail that matters most is which auctions count as eligible. Google includes every auction where your ad showed, plus every auction where it was competitive enough to show. Google's own illustration: an auction where your ad could have appeared at twice its current bid may be counted, while one where you would have needed a 1,000% bid increase may be left out. So the denominator is not every search that matched your keywords. It is the set of auctions you could realistically have entered with the settings you have today.

Two consequences follow from that. First, small day-to-day swings are not necessarily a signal. Changes to your bids, your ad quality or Google's own systems can change which auctions the estimate treats as competitive, so the denominator moves too. Second, impression share can fall when you expand. Add a new region or a broader keyword and more auctions become eligible, so the same number of impressions becomes a smaller share.

Reporting rules behind the number

Impression share is available for campaigns, ad groups, keywords and, in Shopping campaigns, product groups.
Search Partners are excluded. Google states that Search Partners do not distinguish between top and other positions and are not included in impression share data.
Impression share is reported separately for each campaign type and is not aggregated across the account, so there is no single account-wide figure to chase.
Google says the metrics update within one to two days. A "--" in the column usually means there is not enough data yet, for example low traffic or newly added keywords.
In the Google Ads API, Search impression share is reported in a range of 0.1 to 1, and any value below 10% is returned as 0.0999. The lost impression share fields run from 0 to 0.9, and anything above 90% is returned as 0.9001. Treat values at those edges as "below 10%" or "above 90%", not as exact readings.

Google reports the two networks in separate columns. Search impression share is the impressions you received on the Search Network divided by the estimated impressions you were eligible to receive there. Display impression share is the same ratio for the Display Network. They describe different kinds of inventory, so they should never be averaged together or compared as if they were one metric.

On Search, eligibility starts with queries that trigger your keywords inside your targeted locations, languages and schedule. On Display, the pool is made of placements and audiences, and Google's improvement advice is different: work on display ad quality and review managed placements. Google notes that adding placements grows the pool, which lowers share unless budget grows with it, while removing placements can lift share simply because the pool got smaller.

Some campaign types calculate impression share their own way. Shopping impression share comes from Search Network traffic only, not Display or Search Partners, and when several of your Shopping ads appear in the same auction only your first impression counts toward the share. Performance Max combines Search and Shopping impressions in both the numerator and the denominator. Hotel campaigns measure share inside the Hotel ads booking module.

Search exact match IS divides the impressions you received by the estimated eligible impressions for searches that matched your keywords exactly or as close variants, regardless of the match type you actually used. It is available only for Search Network campaigns and not for Shopping. Google suggests using it when broad match keywords show low overall share. If exact match share is healthy while overall share is low, the shortfall sits in the broader queries, and the search terms report shows which of those to add as keywords with their own bids or to block as negatives.

Google attributes eligible impressions you did not receive to one of two causes, and the split between them is usually the most useful thing on the screen.

Search lost IS (budget) is the percentage of time your ads were not shown on the Search Network because the budget was insufficient. It is available at campaign level only, because budgets are set per campaign. Search lost IS (rank) is the percentage of time your ads were not shown because of poor Ad Rank in the auction. Ad Rank is driven by your bid together with ad quality and other auction-time factors, so a rank loss points to a bid problem, a quality problem, or both. Display has matching columns: Display lost IS (budget) and Display lost IS (rank).

For a Search campaign, the three figures together roughly account for the whole eligible pool: impression share plus lost to budget plus lost to rank. A hypothetical example: a campaign shows 55% Search impression share, 15% lost to budget and 30% lost to rank. Doubling the budget can recover at most the 15%. The larger gap is in Ad Rank, and money alone will not close it.

One reporting quirk catches people out. Google notes that lost IS (rank) is not shown on the Ad groups tab if the campaign ran out of budget at any point during the selected date range. If rank loss is blank at ad group level, look at the campaign's budget column before concluding there is no rank problem.

Being eligible and showing is one thing. Showing near the top of the results page is another, and Google reports it separately. Google defines top ads as ads adjacent to the top organic results. They are generally above the organic results but can appear below them for some queries, and their placement changes with the query. Absolute top means the very first ad among top ads.

Search top IS: impressions you received among top ads divided by the estimated impressions you were eligible to receive among top ads.
Search abs. top IS: impressions you received in the absolute top position divided by the estimated impressions you were eligible to receive among top ads.
Search lost top IS (budget) and (rank): how often your ad did not show anywhere among top ads because of a low budget or poor Ad Rank.
Search lost abs. top IS (budget) and (rank): how often your ad was not the very first ad among top ads because of a low budget or poor Ad Rank.

Do not confuse these with Impr. (Top) % and Impr. (Abs. Top) %. Those two are rates calculated on your own impressions: of the impressions you received, what percentage appeared among top ads or in first position. Google explicitly advises against using those location rates as bidding targets, because they can fall as bids rise when higher bids let you into more competitive auctions in a worse position. The top impression share metrics, by contrast, are the ones Google says you can bid against.

Click the Campaigns icon, then choose Campaigns or Ad groups from the section menu. For keywords, open the Audiences, keywords and content menu and choose Search keywords.
Click the columns icon above the table.
Open the Competitive metrics group and tick Search impr. share and Display impr. share, plus the lost IS, top IS and absolute top IS columns you need.
Click Apply. The columns now appear in the statistics table and can be saved as part of a custom column set.

To compare yourself with other advertisers, use the auction insights report, available for Search, Shopping and Performance Max campaigns. For Search it shows impression share, overlap rate, outranking share, position above rate, top of page rate and absolute top of page rate. Two limits are worth knowing. The report does not show insights when your impression share is below 10%. And a competitor's impression share in your report is measured against your eligible auctions, so it will not match the figure that competitor sees in their own account.

Google's own improvement guidance is short: raise the budget, raise bids, improve ad quality, or change the size of the pool through targeting. The work is in matching the right lever to the column that is actually moving.

When lost IS (budget) is high

The campaign runs out of money before searchers run out of demand. Before adding budget, check whether the conversions it already produces are profitable, because extra budget mostly buys more of the same traffic. There are also options that need no new money: tightening the location or ad schedule to where and when the campaign converts, lowering bids so the same budget covers more auctions, or shifting budget from a campaign that shows no budget loss. Google notes that reducing regional targets can lift impression share, while reminding you that it also shrinks the number of impressions available.

When lost IS (rank) is high

The ad is losing auctions on Ad Rank. Start with the quality side, meaning ad relevance, expected click-through rate and landing page experience, since gains there improve rank without pushing up cost per click. Raise bids only where the keyword's economics support it. On Smart Bidding strategies, a high rank loss can reflect the strategy choosing to skip expensive auctions in order to hold a CPA or ROAS target. In that case the target, not a manual bid, is the setting to review.

When visibility is the goal

Target impression share is an automated strategy that sets bids to show your ad anywhere on the page, among top ads, or as the absolute top ad for a chosen percentage of eligible auctions. Google suggests it for brand terms, for example a 100% target on searches for your own brand name. It includes a maximum CPC bid limit, and Google warns that a limit set too low will stop the strategy from reaching its goal. Existing bid adjustments are ignored under this strategy, except a -100% device adjustment, which still excludes that device. Impression share here counts only the Google Search Network, not Search Partners.

The table below maps the main columns to what each one measures and the first thing to check when it changes.

Impression share columns at a glance
Column	What it measures	First thing to check
Search impr. share	Impressions received divided by estimated eligible impressions on the Search Network	Which of the two lost columns explains the gap
Search lost IS (budget)	Eligible impressions missed because the budget ran out (campaign level only)	Profitability of current conversions before adding budget
Search lost IS (rank)	Eligible impressions missed because of poor Ad Rank	Ad quality, bids and any Smart Bidding target
Search top IS and abs. top IS	Share of eligible top-of-page impressions won, or won in first position	Whether top placement matters for this campaign's goal
Search exact match IS	Share on searches matching keywords exactly or as close variants	Search terms report for broad queries pulling overall share down

What this means for businesses advertising in Thailand

Advertisers in Thailand often run Thai-language and English-language keywords side by side, sometimes inside a single campaign. Because impression share is reported per campaign and per keyword, a blended campaign figure can hide two very different situations: a Thai keyword set losing on budget next to an English set losing on rank. Check keyword-level share and lost IS (rank) for each language before touching the campaign budget, and consider separate campaigns if the two sets need different budgets.

Location targeting changes the picture as well. A campaign targeting the whole country has a much larger eligible pool than one targeting a few Bangkok districts, so expanding from city to country will usually lower impression share even when impressions rise. Read the impressions count and the share together. Finally, many local businesses bid on their own brand name to protect it in the results; a separate brand campaign on Target impression share is the setup Google itself points to for that case.

There is no universal benchmark, and Google does not publish one. The right level depends on the campaign's goal: brand campaigns usually aim high because the searcher is already looking for you, while for generic keywords the last few points of share tend to be the most expensive auctions. Judge the trend and the split between budget and rank loss rather than a single number.

A "--" usually means there is not enough data yet, for example low traffic or newly added keywords. Google also notes that these metrics can take 24 to 48 hours to process, so very recent date ranges may be empty.

No, Search Partners are not included in impression share data. Target impression share bidding also counts only the Google Search Network.

Why can't I see lost IS (budget) for my ad groups?

Lost IS (budget) exists only at campaign level, because budgets are set per campaign. Google removed it in June 2022 from saved Report Editor reports that also used ad group or keyword dimensions.

Should I raise the budget or the bids first?

Let the lost IS columns decide. If most of the gap is lost to budget and the campaign converts profitably, budget is the lever; if most of it is lost to rank, extra budget will not help and ad quality or bids are the lever.

Impression share works best as a diagnostic. It shows how much eligible demand you are missing and whether budget or Ad Rank is the constraint. Read it with the two lost columns, at the right level, and next to conversion data, and it turns into a short list of specific changes instead of a number to push upward for its own sake. If you would like a second opinion on what is limiting your campaigns, Relevant Audience's Google Ads management team can review impression share together with conversion data, and the search advertising service covers keyword and bid structure. For reliable conversion data underneath those decisions, see GA4 setup and migration.