Impression Share is the percentage of eligible impressions an ad received compared with the total impressions it could have received.
Example of Impression Share
If a Microsoft search campaign receives 600 impressions from an estimated 1,500 eligible opportunities, its impression share is 40%. The advertiser investigates the reasons for missed eligibility-adjusted exposure rather than interpreting that figure as 40% of the entire market.
Why Impression Share matters
It matters because Microsoft Advertising can reach valuable search and professional audiences that are often overlooked. Clear measurement and audience structure help the channel complement Google Ads rather than simply duplicate it.
Related terms
Frequently Asked Question
What does Impression Share mean?
Impression Share means the percentage of eligible impressions an ad received compared with the total impressions it could have received.