Marketing · business glossary
What is Impression share?
By Shivam Bhandari · Reviewed 31 October 2026 · How we write
definition
The percentage of all possible times your ad could have shown for a given search or audience that it actually did show.
Impression share explained
Impression share is the percentage of times your ads were shown out of all the times they were eligible to show, used mainly in search advertising.
formula
Impression share % = Impressions received ÷ Impressions eligible × 100
example
If your ad could have appeared 10,000 times but appeared 6,000 times, impression share is 60%.
why it matters
Low impression share shows missed opportunities due to budget or ad quality.
common mistake
Chasing 100% impression share on keywords that don't convert.
Frequently asked questions
What is Impression share?
The percentage of all possible times your ad could have shown for a given search or audience that it actually did show. Impression share is the percentage of times your ads were shown out of all the times they were eligible to show, used mainly in search advertising.
How do you calculate Impression share?
Impression share % = Impressions received ÷ Impressions eligible × 100. If your ad could have appeared 10,000 times but appeared 6,000 times, impression share is 60%.
Why does Impression share matter?
Low impression share shows missed opportunities due to budget or ad quality.
What is a common mistake with Impression share?
Chasing 100% impression share on keywords that don't convert.
Related terms
Impressions
The number of times an ad or piece of content was displayed, regardless of whether anyone engaged with it.
CTR (click-through rate)
The percentage of people who saw an ad or link and actually clicked on it.
SEO (search engine optimisation)
The practice of improving a website so it ranks higher in search results for relevant terms, driving free traffic over time.