premjithbpk, I'm assuming you're getting your "impressions" data from the Google Search Console. I've never been happy with Google impressions data. The determination of impressions has changed over time, but it's always felt arbitrary to me, as the way search terms are organized by Google has never suggested to me a useful connection with the actual phrases of queries searched. This is particularly true currently in the age of BERT query refinements.
FYI in any case, here's Google's GSC Help document describing several important metrics, including Impressions....
What are impressions, position, and clicks? [
support.google.com...]
(From the help article... my emphasis added...) This page helps explain impressions, position values, and click data in the Search Analytics report.
- The heuristics described here - such as the visibility requirement for an item in a carousel, or the position numbering - are subject to change.
There's a lot in about impressions in the Google article to be read and digested.
And then there's "Monthly Search Volume", that elusive predictive number which you're comparing with impressions. The first question I have for you is: where do you get your search volume data?
Search Volume is a monthly *prediction* of how often a word or phrase is searched. It's generally gotten from advertising search data... and in addition to Google's tool, there are many SEO suites available that include "keyword" data, with accuracy of predictions in part posited on the idea that if many search marketers over the years have spent lots of money targeting, say, a specific two or three word phrase, they must be doing so because they've been making money doing so.
Search volume tools have been most successful for me as tools indicating
relative volumes of searches for some vocabulary choices... but in my experience they're almost never right for
absolute numbers of searches.
In my experience, they all fail miserably in predicting search volume on longtail and rarely searched terms, especially when applied to organic search targeting.
Google keyword tools, for reasons both of confidentiality and of expected mathematical uncertainty, don't give precise numbers. Other tools, I should add, don't have Google data... but again, all of the tools are generally useful for predicting relative volumes.
While you've gotten good answers above to some very basic points of your question, you need also to consider the imprecision of the numbers you're working with. I should add also that the idea of ranking for specific two and three word keyword phrases is getting more obsolete as time goes on, and as search becomes more about concepts and less about precise phrases, SEOs need to reconceive how they're targeting phrases.
