Search Impression Share

Search Impression Share is the percentage of impressions your ads received on the Google Search Network compared to the total number of impressions you were eligible to receive. It is calculated as Search Impressions / Total Eligible Search Impressions and is the primary visibility metric for Search campaigns.

Key Takeaways

• Search IS = Search Impressions / Total Eligible Search Impressions
• Specific to the Google Search Network (excludes Display, Video, and Shopping)
• Google provides two diagnostic columns: Search Lost IS (Budget) and Search Lost IS (Rank)
• Branded keyword search IS should typically be 90%+ to protect your brand
• Non-branded search IS targets vary by strategy — 100% is rarely cost-efficient

What Is Search Impression Share

Search Impression Share is the Search Network-specific version of the broader Impression Share metric. It tells you what percentage of all searches matching your keywords and targeting actually showed your ad.

Google breaks the missing impressions into two clear categories:

Column	Meaning	Primary Fix
Search Lost IS (Budget)	Impressions lost because daily budget was exhausted	Increase budget or reduce CPC
Search Lost IS (Rank)	Impressions lost because Ad Rank was too low	Improve Quality Score or increase bids

In the 2026 Google Ads interface, additional position-specific metrics are available:

• Search Top IS — percentage of impressions shown above organic results
• Search Abs. Top IS — percentage of impressions shown in the very first ad position

How It Works

Google evaluates every search query against your active keywords and targeting settings. If your keyword matches and your campaign is eligible, that search counts as an eligible impression — whether your ad actually appeared or not.

The calculation happens in real time, but Google reports aggregated data at the campaign and ad group level. Search Impression Share data is not available at the keyword level.

Factors that determine eligibility:

1. Keyword match — the search query triggers one of your keywords
2. Location targeting — the searcher is in your targeted geography
3. Ad schedule — the search occurs during your active ad schedule
4. Campaign status — the campaign, ad group, and ads are all enabled and approved
5. Budget availability — your daily budget has not been exhausted
6. Ad Rank sufficiency — your Ad Rank meets the minimum threshold for the auction

Practical Example

A dental practice runs a local Search campaign targeting “dentist near me” and related terms:

Metric	Branded Terms	Non-Branded Terms	Total Campaign
Impressions	4,500	3,000	7,500
Eligible Impressions	5,000	10,000	15,000
Search IS	90%	30%	50%
Lost IS (Budget)	2%	45%	30%
Lost IS (Rank)	8%	25%	20%

Analysis:

• Branded terms at 90% — strong. The 8% lost to rank is likely from competitor bidding on the practice name. Consider slightly higher branded bids.
• Non-branded at 30% — the practice is missing 70% of potential patients searching for local dental services
• 45% lost to budget on non-branded terms means the $50/day budget runs out by early afternoon

Action plan:

• Increase daily budget from $50 to $90 to capture the budget-lost impressions
• At current CPC of $8 and 6% conversion rate, the additional 4,500 impressions would yield approximately 270 clicks and 16 additional appointment bookings per month

Why It Matters

Search Impression Share is uniquely valuable because it quantifies the demand you are leaving on the table:

• Growth opportunity sizing — if your Search IS is 40%, you know there is 60% more search demand available. This directly informs budget and bid decisions.
• Budget sufficiency check — high Lost IS (Budget) is the clearest evidence that increasing budget will generate incremental results
• Competitive health — declining Search IS with stable budgets signals competitors are improving their positions or new competitors are entering the auction
• Brand protection — low Search IS on branded terms means competitors are showing ads on your brand name. This is typically the highest-ROAS traffic and should be protected at 90%+ impression share.

Use Search Impression Share as a strategic planning tool, not just a reporting metric. It answers the question most other metrics cannot: “how much more could we be getting?”