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Posted on May 2, 2008

Max Keyword Limit

Max Keyword Limit
Posted on May 2, 2008

What is the Optimal Max Keyword Length?

If you’re one of those Adwords managers who keeps encountering warnings that you’ve reached the account limit for maximum number of keywords, then this posting is for you. We’re interested in knowing, particularly for online stores, how keywords perform according to length of keyword phrase.

PPC Managers Gone Wild

When it comes to creating keywords, the concatenation function is sweet. With a little imagination, a PPC Manager can transform a list of 500 root keywords into 15,000 with several hour’s work (creating them is the fun part, maintaining them can be hades). There is no limit to the number of combinations a PPC Manager, with an overdeveloped imagination, can create . . . errr, except for Google’s max keyword limit.

Yo! Yahoo!!!?? More keywords! When are you going to buy some servers??!!

If you’re up against Google’s max keyword limit, then you probably have a separate problem:  Low Search Volume.

Max Keyword Length for Online Stores

We encounter the issue of keyword length most often when we create campaigns for online stores. Last summer we created some very large accounts for several lines of similar merchandise which have literally thousands of combinations of products, custom made for types, colors, material, etc. We found in our preliminary research that prospective consumers really were performing relatively long searches to describe the combinations of product attributes for which they were searching. Of course, the next step was that we maxed out the account with about 40,000 keywords and 2,000 ads.

Case Study: Optimal Keyword Length?

For the above mentioned account, a recent analysis showed that the keywords performed as follows (paraphrased somewhat, but more or less extracted from a report):

We have applied a rather radical PPC long-tail approach involving the concatenation of the primary keyword with product attributes. Has the approach been effective? Of about 36K remaining active keywords, only 6k have earned impressions over the past six months. Does that mean that 30,000 are a waste of space? For those shorter than 40 to 45 characters, maybe not. We analyzed those keywords with impressions according to length of search phrase. Our results can be summarized as follows:

All keywords with impressions – Last six months

Phrase Length

# KW’s



Conv %

Length 10 to 14





Length 15 to 19





Length 20 to 24





Length 25 to 29





Length 30 to 39










Clearly the longer keywords are outperforming the shorter ones on the basis of acquisition cost. The results are not a surprise, although it’s always nice to confirm our understanding of the value of applying a long-tail approach for PPC. In terms of performance, this account has improved tremendously since we restructured it (acquisition costs have decreased by 43%), and we attribute much of this improvement to the elimination of short broad match keywords, and the implementation of our long-tail phrase match approach as performed during the intitial account restructuring.

For this account, we would categorize keywords longer than 25 characters as being “Radically long” and all keywords longer than 35 as being excessively long. Radically Long keywords have performed quite well, and it appears that some excessively long keywords have also converted acceptably well.

Longer is Better

Our experience shows that for some online stores, keywords up to 40 characters can significantly outperform shorter keyword search phrases. Search phrases are getting longer (for Google) as consumers are rewarded for using more key strokes. GE and GM can afford to purchase short keyword phrases; the rest of us should avoid them. We generally view any keyword phrase shorter than 10 characters with a healthy degree of skepticism. If you’re an Advertiser who wishes to keep his shirt, you should do likewise.

How Long is Too Long?

Google will allow a keyword maximum of up to 80 characters or ten words. However, we would generally consider a length of 40 characters as representing a par maximum length for many online stores, and 35 characters as representing a par maximum length for other advertisers. We would generally categorize keyword phrases longer than those par maximum length values as being “Excessively Long Keywords.” Excessively Long keywords generally do not warrant the cost associated with maintaining them. Aside from that, given the limits on maximum number of keywords allowed for an account, there is an opportunity cost associated with keeping Excessively Long Keywords. It’s not that Denver PPC doesn’t allow their use, but we require our PPC Managers to provide some justification for bidding on them.