What's a good impression share?

There's no universal target, it depends on strategy. A brand deliberately bidding conservatively on broad terms may accept a lower impression share; a brand aggressively pursuing its core keywords typically aims for 70-90%+ on those specific terms.

Why would I want to raise my budget if my impression share is already high?

You generally wouldn't, a high impression share (90%+) suggests the campaign is already capturing most available demand, so more budget would be better spent expanding into new keywords or audiences rather than raising an already-high share further.

Can impression share be 100%?

Yes, in principle, though in practice most campaigns settle somewhat below it due to natural fluctuations in competition and eligibility, and pursuing the last few percentage points often costs disproportionately more than it's worth.

Does impression share apply to display and video, or just search?

It's reported for both Search and Display campaigns in Google Ads, though the concept and its usefulness are most commonly discussed in the context of Search, where auction dynamics are most direct.

Does impression share affect Quality Score?

Not directly, they are related but separate: Quality Score affects how competitively an ad can win auctions, and impression share reports the resulting outcome of that competitiveness across all eligible auctions.

How often should impression share be reviewed?

Regularly, especially for core, high-value keywords, since competitive dynamics (new entrants, seasonal bid pressure) can shift Lost IS quickly without any change to your own account settings.

What Is Impression Share?

Impression share is the percentage of impressions an ad actually received out of the total number it was eligible to receive. It measures how much of the available, relevant auction volume a campaign is actually capturing, rather than how well it's performing once it does show, which makes it a demand-capture metric rather than an efficiency one.

Every time a search or a placement matches a campaign's targeting, that's a potential impression the campaign was eligible for. Impression share compares how many of those eligible opportunities actually resulted in the ad being shown. When it's below 100%, the platform also reports why, breaking the gap into two distinct causes: Lost IS (budget), where the campaign ran out of daily budget before it could compete in every eligible auction, and Lost IS (rank), where the ad's rank (bid combined with Quality Score) simply wasn't competitive enough to win the auction, even with budget still available.

That split matters operationally, because the two causes call for completely different fixes: a budget-side loss is solved by raising the budget or adjusting pacing, while a rank-side loss requires either a higher bid or a better Quality Score.

Examples & Use Cases

A campaign shows a healthy 4x return on ad spend but only a 40% search impression share, revealing it's missing 60% of available, relevant demand, real headroom for growth without changing efficiency at all.
An account diagnoses a 25% Lost IS (budget) on its top-performing campaign and raises the daily budget, capturing meaningfully more conversions at a similar CPA.
A brand with strong Quality Scores across the board still shows 30% Lost IS (rank) on one specific keyword, traced to two new competitors bidding aggressively above the brand's current bid ceiling.

How are impressions calculated?

Impression Share = (Impressions Received ÷ Total Eligible Impressions) × 100

The eligible impressions figure isn't directly visible, it's inferred by the platform from targeting, budget, and Quality Score data, so impression share is reported as a percentage rather than calculated manually from raw numbers an advertiser has full visibility into.

Why It Matters and How to Improve

Impression share tells a different story than most performance metrics: a campaign can post a strong CPA and still be missing a large share of available demand. Splitting lost impression share into budget versus rank is what tells an advertiser whether the right fix is to raise the budget or improve the ad's competitiveness, two very different actions that impression share alone, without the breakdown, wouldn't distinguish between. Reporting that helps you spot where demand is being missed turns that split into a decision rather than a number.

Impression share is best read alongside performance metrics like CPA or ROAS, not on its own. A high-performing, low-impression-share campaign represents genuine growth headroom, capturing more of that missed demand at similar efficiency. A low-performing, low-impression-share campaign is a different, more cautionary signal, and warrants checking efficiency before pushing for more volume. The Lost IS split should always be read before deciding on a fix.

Frequently Asked Questions

What's a good impression share?: There's no universal target, it depends on strategy. A brand deliberately bidding conservatively on broad terms may accept a lower impression share; a brand aggressively pursuing its core keywords typically aims for 70-90%+ on those specific terms.
Why would I want to raise my budget if my impression share is already high?: You generally wouldn't, a high impression share (90%+) suggests the campaign is already capturing most available demand, so more budget would be better spent expanding into new keywords or audiences rather than raising an already-high share further.
Can impression share be 100%?: Yes, in principle, though in practice most campaigns settle somewhat below it due to natural fluctuations in competition and eligibility, and pursuing the last few percentage points often costs disproportionately more than it's worth.
Does impression share apply to display and video, or just search?: It's reported for both Search and Display campaigns in Google Ads, though the concept and its usefulness are most commonly discussed in the context of Search, where auction dynamics are most direct.
Does impression share affect Quality Score?: Not directly, they are related but separate: Quality Score affects how competitively an ad can win auctions, and impression share reports the resulting outcome of that competitiveness across all eligible auctions.
How often should impression share be reviewed?: Regularly, especially for core, high-value keywords, since competitive dynamics (new entrants, seasonal bid pressure) can shift Lost IS quickly without any change to your own account settings.

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