Keyword Effectiveness Index (KEI)

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Keyword Effectiveness Index (KEI)

Introduction: Many people new to marketing think that Keyword Effectiveness Index (KEI) is the magic formula to achieve high ranking in the search engines and thereby secure a steady stream of money. The claim is supported by the documentation of almost all keyword research tools and has been repeated by thousands of inexperienced marketing people.

I say that if anyone says that the Keyword Effectiveness Index (KEI) is great to find good keywords/search terms, without explaining any of the drawbacks, then they are either out to cheat you or they just don’t know any better.

Definition: Keyword effectiveness index: A mathematical representation of the popularity of a keyword measured in number of searchers (demand), compared to its popularity measured as the number of pages in a search engines index (supply).

Description: KEI is a statistical formulation that reveals the most effective keyword phrases and terms to use in optimizing your web pages for. Efficiency can be many things. According to KEI, it is efficient to optimize for keywords that have many searchers, but only a few competing pages.

The lower the KEI, the more popular your keywords are, and the less competition they have. That means that you might have a better chance of getting to the top in the search engines and receive a good number of searchers for your effort.

Example: Suppose the number of searches for a keyword is 821 per day and Google displays 224,234 results (pages) for that keyword. Then the ratio between the popularity and competitiveness for that keyword is:

224,234 divided by 821. In this case, the KEI is 273.

Example on the opposite: Suppose the number of searches for a keyword is 2 per day and Google displays 11,224,234 results (pages) for that keyword. Then the ratio between the popularity and competitiveness for that keyword is:



Explanation: According to the KEI definition, the best keywords are those that have many searches and that don’t have much competition in the search results. A low KEI is therefore preferable.

In our example, it is clear that the keyword with a KEI of 273 sounds as a good keyword to optimized a pages for. It is just as clear, in the example on the opposite, that the keyword that has lots of competitors and a low number of searchers which gives a KEI equal to 5,612,117 is a tough fight for a small prices (unless the two searchers are very valuable;-).

However, the KEI make no statement about the quality of the competition. While there might only be a few competitors in the search results, these competitors could be big players with big SEO teams, quality content and thousands of back links.

The number of search results can’t really tell you whether it is easy to get your web site listed in the top 10 results for that keyword or not. It’s much easier to move your web site from position 20,000 to position 12,000 than from position 190 to position 6.

In addition, the KEI factor is not a scientific number. It is more like a rule of thumb.
We will expect:

• The KEI for a keyword to increase if its popularity increases. Popularity is defined as the number of searchers.
• The KEI for a keyword to decrease if it becomes more competitive. Competitiveness is defined as the pages in the search engines index.

As a general rule, it isn’t advisable to select or deselect keywords wholly on the basis of numbers like KEI.

A better metric would be relevancy. Some of your keywords you are able to rank for in the search engines and other will give your users a good experience.

History: There haven’t been many successful metrics that have been calculated by two or more variables. The Keyword effectiveness index has been the most successful.

Future: There is a need for more useful variables in SEO and I predict there will come many in the future.

How to practice: When you have a keyword phrases, with a high, medium or low KEI, you need to be able to answer: Is there a reason why the KEI might be giving an incorrect picture?

There can be many reasons why KEI are showing you something you can’t use. Here are some of the reasons:

1. The position of the words in the keyword phrases is unnatural.
Ex. “keyword report” has 534,000 pages in Google’s index, and the more unnatural “report keyword” has 29,100 pages. This doesn’t mean there is 18 times less competitions for “report keyword”.
2. More words in a keyword phrase means a much smaller changes to find them in a webpage.
3. Search engines don’t give the accurate number of pages in their index.
4. The number of searchers isn’t an accurate number and some keywords are inflated by the use of automated tools.

By blindly using KEI to select keywords, you run the risk to select keywords that have words in an unnatural order, long keyword phrases and where automated tool inflate the search numbers. Not good if you were looking for keyword phrases with little competition and many searchers.

Tips: Always ask yourself if there is a good reason why a keyword phrase has a low number, before you get all excited.

Some keyword phrases convert badly to customers and therefore it is easier to rank for. Do you want to put a big effort to rank for low value keywords?

Links: Keyword, Keyword Demand, Keyword Phrase, Search term.

Conclusion: Use Keyword Effectiveness Index (KEI) carefully. Is there any reason why KEI shows it is a good keyword to use, but it is not?

What is your experience with Keyword Effectiveness Index (KEI)?
Do you like to use Keyword Effectiveness Index (KEI)?
Do you have any alternative methods to find good keyword/search phrases?

Alternative to KEI: I like to use Adwords for keyword research. I can test thousand of keywords and get CTR, conversion rate and the most precise number of searchers etc.(I could calculate Keyword Value = Number of Searcher * CPC). When I have my list of worthy keywords, I can go to the results page to see if the results are relevant and something I would be able to compete with.



  1. Brian Ostergaard April 2, 2008 at 4:15 pm - Reply

    Hi Reggy,

    KEI is almost always defined in a special way.

    There is no golden rule when it comes to KEI.

    For most keywords you have a small number of searchers and a big number of websites that is in the index for that keyword.

    I prefers to compare big number instead of very small numbers.

    If you look at the example on the opposite. We get at KEI= 5 612 117. If we define KEI as you suggested we changes the denominator and numerator and get: KEI = 0.000000178.

    It all comes down to: Do you like big or small numbers?

  2. Lance April 20, 2008 at 3:33 am - Reply

    I am about to launch just such a new seo variable as you have been talking about. KEI is completely subjective and extrordinarily useless. You can have keywords/phrases with a KEI of .2 and yet to optimize and link build agressively an average person stands a good chance of getting to the first page. That is what KEI can’t tell you. But I will be telling the world in about 30 days from now. Being looking for KCI soon.

  3. sushilver July 17, 2008 at 8:09 am - Reply

    this is right…. if you taking higher KEI keywords that means keyword is not much more searcheable and if you come on top from this keyword then what’s the benefit of that.

  4. Vladek February 7, 2009 at 3:27 am - Reply

    I believe you should optimize a site for the most common keywords / phrases in its respective field but also use some of high KEI phrases as well. If you combine the both approaches you might end up getting the most of SEO work.

  5. Sales Training - Management March 9, 2009 at 6:19 pm - Reply

    Seems to me this article was written for SEM with the number of “keyword” keywords words you’re using. oops, I gave you another one.

    At any rate, I tend to look at where our site is in relationship with our competitors and then look at where we want to be. I have never looked at KEI. What I have done is research my market and learn what the keywords are that are being used in search. Then optimize accordingly. You have to know your market. You need to know where they are. You need to know where and what they are searching for. Don’t guess.

    Always be training.

  6. Patrick November 27, 2009 at 8:36 am - Reply

    At wordtracker they define KEI as P^2/C.
    P for popularity and C for competitiveness.
    adwords 3600 searches (+/- 120 per day)
    google 54300 results
    KEI = 120^2/54300 = 0.265

  7. leonahaha December 31, 2009 at 7:10 am - Reply

    At wordtracker they define KEI as P^2/C.
    P for popularity and C for competitiveness.
    in fact,how to calculate KEI?
    what’s the standard of KEI? the higher? how high?

  8. kazanç June 7, 2010 at 6:31 am - Reply

    Thanks for the informative article.? will pay attention to what have been explained in thi article and i expect to get the good result.

  9. Mark August 26, 2012 at 6:23 pm - Reply

    I used KEI in the pasted, but I never got any good result…so I stopped using it.

  10. Search engine optimization September 4, 2012 at 9:05 pm - Reply

    I really liked that post and found it very useful. Your site is very informative with lots of great stuff on it. Thanks.

  11. amrutha November 28, 2012 at 6:41 am - Reply

    to choose an keyword whether the kei must be low or high?

  12. Mike December 20, 2012 at 12:16 pm - Reply

    Amrutha – there are many factors involved in selecting a keyword but the simple answer to your question is that a higher KEI is better.

  13. Ashik July 11, 2017 at 7:40 pm - Reply

    KEI=Result/searchers.My question is how to find searchers. Adword shows only avg monthly search result so where I can get Searchers number????

  14. Brian Østergaard September 19, 2017 at 1:40 pm - Reply

    Hi Ashik,

    I would use Adwords average monthly searches. I know it is not perfect and with less than 10 average monthly searches, you don’t get any results.

    If you are advertising in Adwords, you are able to get more precise numbers. Inside Adwords you would be able to get your impressions and impressions share. So you get searches = impressions / impressions share.

    So if you have 500 impressions and a impressions share of 50% you get:

    500/0.5=1000 searches a month (if you chosen a month)

    If you use Adwords, when you would be able to get conversion rate, competition, search terms and many other metric that is fare better than KEI.



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