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If AdGroups can have 20,000 keywords, why does everyone recommend <30?

Visitor ✭ ✭ ✭
# 1
Visitor ✭ ✭ ✭

I've noticed that Google increased the max number of keywords per AdGroup on a few occasions and it now sits at 20,000 max. So why then, do they keep increasing it if experts are telling us to keep it around 30?

 

I have some pretty big lists. All competitive, all relevant and all somewhat frequent. What potential harm is there with an AdGroup of ~300 keywords?

 

Note: there will be 12 AdGroups covering all aspects of our business. This has been laid out as 1 AdGroup per service.

 

Thanks Smiley Happy

 

Jon

1 Expert replyverified_user
1 ACCEPTED SOLUTION

Accepted Solutions
Marked as Best Answer.
Solution
Accepted by Karishma (Google Employee)
September 2015

Re: If AdGroups can have 20,000 keywords, why does everyone recommend

Collaborator ✭ ✭ ✭
# 2
Collaborator ✭ ✭ ✭

Hello,

 

My personal opinion is that the 20.000 limit is more aimed for ad groups about spare parts , where characteristics of a spare part can include hundreds of combinations between part codes, measurements, destination of the spare part, colours, manufacturing year, compatible models and such.

 

Let's say that all these keywords are phrase matches. Because in the phrase match, the order of words matters, the total amount of keywords would be expressed mathematically in Permutations without repetition.

 

If we have 7 or 8 words in a keyword, the number of permutations without repetition would be factorial of 7 or 8 aka 7! or 8! which are calculated like this 

 

7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5,040

8! = 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 40320

 

So 20.000 keywords per ad group only covers only half of the permutations possible by using 8 words in a keyword, such as 8 characteristics of a spare part.

 

Read more from here :

http://www.mathsisfun.com/combinatorics/combinations-permutations.html

 

I have only met one case in this forum where the keywords limit was reached and it got solved by deleting keywords.

 

Back to your problem : "What potential harm is there with an AdGroup of ~300 keywords?"

Answer : low relevancy of Ads when triggered by all those 300 keywords resulting in low CTR, in low QS and higher cost per click for you.

 

Using fewer keywords per ad group increases your chance of relevancy for your Ad Text. So keywords are linked to Ad Text.  Also when you keywords are included in the headline of the Ads and the search term includes the words from the keyword , the text in your Ad is changed to Bold ( just for the keyword).

It would be difficult to have a set of Ads which include all the 300 keywords in the Ad Text.

View solution in original post

Marked as Best Answer.
Solution
Accepted by Karishma (Google Employee)
September 2015

Re: If AdGroups can have 20,000 keywords, why does everyone recommend

Collaborator ✭ ✭ ✭
# 2
Collaborator ✭ ✭ ✭

Hello,

 

My personal opinion is that the 20.000 limit is more aimed for ad groups about spare parts , where characteristics of a spare part can include hundreds of combinations between part codes, measurements, destination of the spare part, colours, manufacturing year, compatible models and such.

 

Let's say that all these keywords are phrase matches. Because in the phrase match, the order of words matters, the total amount of keywords would be expressed mathematically in Permutations without repetition.

 

If we have 7 or 8 words in a keyword, the number of permutations without repetition would be factorial of 7 or 8 aka 7! or 8! which are calculated like this 

 

7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5,040

8! = 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 40320

 

So 20.000 keywords per ad group only covers only half of the permutations possible by using 8 words in a keyword, such as 8 characteristics of a spare part.

 

Read more from here :

http://www.mathsisfun.com/combinatorics/combinations-permutations.html

 

I have only met one case in this forum where the keywords limit was reached and it got solved by deleting keywords.

 

Back to your problem : "What potential harm is there with an AdGroup of ~300 keywords?"

Answer : low relevancy of Ads when triggered by all those 300 keywords resulting in low CTR, in low QS and higher cost per click for you.

 

Using fewer keywords per ad group increases your chance of relevancy for your Ad Text. So keywords are linked to Ad Text.  Also when you keywords are included in the headline of the Ads and the search term includes the words from the keyword , the text in your Ad is changed to Bold ( just for the keyword).

It would be difficult to have a set of Ads which include all the 300 keywords in the Ad Text.

Re: If AdGroups can have 20,000 keywords, why does everyone recommend

Explorer ✭ ✭ ☆
# 3
Explorer ✭ ✭ ☆

Hi Jon,

 

One of the best practice is make sure that you distributed your keywords into theme based Adgroups in your campaign. If you are having a Adgroup of 300 keywords, then there are possible chances that your quality score might get low. Which lead to High CPC and ultimately leading to high CPA if that is metric of checking the ROI.

 

Another important aspect of grouping the keywords in relevant theme based adgroup is that you can write targeted Adcopies for individual keywords which will improve your CTR as well.

 

You can also increase the performance further by testing one single keyword per Adgroup this will help you test the different keywords match type for the same keywords in same adgroups. ( Reason: Some times keywords with different match types seems to perform better than the added keyword match type on campaign setup)

 

Hope this helps you a bit!

 

Thanks,

Azeem Shaikh

 

 

 

 

Azeem Shaikh
SEM Freelancer & Consultant.
Adwords & Bing Ads Certified Individual.

Re: If AdGroups can have 20,000 keywords, why does everyone recommend

Top Contributor
# 4
Top Contributor

Hello there;
Adrian is correct; The large number of ad-groups is set for big advertisers, running huge inventories of items, in which each item has a slightly different model number, or a slight difference in an "item description" (e.g. "Hotel room king size bed" vs. "hotel room two single beds"... Etc.)
Small-medium businesses would never need to reach these limits, and certainly could run an effective campaign with 30 adgroups and a few dozen / hundreds of keywords.

Moshe, AdWords Top Contributor , Twitter | Linkedin | Community Profile | Ad-Globe
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