- Definition
- Impression share is the impressions an advertiser received divided by the estimated impressions it was eligible to receive.
In plain words
Impression share tells an advertiser how often its ads actually showed out of all the times they could have shown.
An impression share of 70% means the ad showed in about 7 of every 10 eligible searches; the other 3 were lost to budget limits or to a low rank.
Why it matters for brand and paid search teams
On brand campaigns, PPC teams often aim for a very high impression share, because every missed impression is a chance for someone else to take the click. The lost share tells them whether to raise budget or improve rank.
Brand and legal teams sometimes ask for a competitor's impression share. No outside tool can provide it. Knowing why helps you avoid misleading reports.
How it works
Google calculates impression share from the advertiser's own data: impressions received divided by the total eligible impressions, which it estimates from targeting, approval status, bids and quality. It splits the loss into lost impression share (budget) and lost impression share (rank).
Related measures describe position: top impression share and absolute top impression share. Microsoft Advertising reports impression share in its auction insights data as well.
These figures exist only inside the advertiser's account and only for its own campaigns. The estimate of eligible impressions is Google's, so read the percentage as a trend over time, not an exact count.
Example
Northstar's brand campaign shows 92% search impression share, 5% lost to rank and 3% lost to budget. In the same week, monitoring shows summit-outdoors.example with 30% observed visibility on Northstar's brand searches.
Both numbers are useful, but they measure different things: Northstar's own eligibility in its auctions, and a competitor's presence in a sample of searches.
Fictional brands and domains, for illustration only.
Common mistakes and misconceptions
A monitoring tool can show a competitor's impression share. Impression share requires the advertiser's own auction data. Outside tools can only count appearances in the searches they check.
100% impression share means no one else appears. It means your ad showed whenever it was eligible. Competitors can still show next to it.
Lost share always means more budget is needed. Check the split. Loss due to rank calls for better bids or quality, not budget.
How to monitor it in Ads Lighthouse
Ads Lighthouse reports observed visibility, the share of monitored searches in which a domain appeared, and labels it as a sample measure. It never presents it as impression share.
It does not import impression share. The optional Google Ads connection opens separate reports from your own account on demand; those rows are not saved or mixed into monitoring reports.
Frequently asked questions
Where do I find my impression share?
In your Google Ads or Microsoft Advertising account, by adding the impression share columns to your campaign or keyword reports.
Can I compare my impression share with observed visibility?
You can read them side by side, as long as each keeps its label. They use different data and different denominators.
Why is my brand impression share below 100%?
Google reports the lost share as budget or rank. On brand campaigns, rank losses often point to a competitor outranking you on some searches, and budget losses to a daily cap reached early.
Official sources
- Google Ads Help: Get impression share data
- Google Ads Help: About top and absolute top metrics
- Microsoft Advertising API: AuctionInsightKpi data object
Sources checked on .