A while back, one of our new hires asked a great question over IM about the number of keywords in an ad group. Here’s a paraphrased version of how the conversation went down:
New Hire: I’ve been told an ideal number of keywords in an ad group is around 15. If you have much more than 15, what are the chances all the words are relevant? Are smaller ad groups better, like in the 5 word range? Does it just make it more tedious to manage having a lot of small ad groups?
Melissa Mackey: Yeah, there comes a point of diminishing returns when you go below 10-15 keywords. That said, I’ve had 1-keyword ad groups for a very high volume term. It just depends – like a lot of things in PPC.
NH: Ok, so you look at diminishing returns and term popularity.
MM: Right, as a rule that works. Also, you might want to isolate smaller groups of keywords to improve quality score. So for example, if you have a few keywords with decent volume and poor quality score, you’d move them to try to improve it.
NH: What if you have a small ad group where one term gets impressions/clicks and the other one is extremely light?
MM: That’s usually ok as long as quality score is relatively similar.
Was I right about that? I’ll get to that in a second.
The “right” number of keywords in an ad group is a subject of much debate. I found a Quora thread that had as many different “right answers” as there were commenters in the thread.
Brad Geddes weighed in on the magic number of keywords in an ad group on the Certified Knowledge blog. Short answer? There is no magic number of keywords – it depends.
A poster on the Adwords Community forum does a good job of illustrating the concept, but then says 5-15 keywords is the right number.
I agree with him, to a point. I usually strive for no more than 15 keywords per ad group. But I also have ad groups with 50 keywords or more, and that’s fine too. It just depends.
The difference comes in whether the ad group is large because there is a large number of related terms out there, or whether the ad group is large simply due to laziness or lack of time. I recently did some keyword research around healthcare marketing, and there are a LOT of variations of “healthcare marketing” that are all closely related.
So how do you decide if you should split up a large ad group into smaller ones?
Look for similarities.
The first thing I do is look for similarities: in keyword theme, performance, or quality score. In fact, while I often say you shouldn’t optimize based on quality score alone, you can use it as a guide here in ad group development. Often the quality score will tell you what Google thinks is similar about the terms.
Quality score also helps you think about ad copy and landing page needs. If you have a bunch of relevant keywords with a low quality score and you’re not in an industry with traditionally low quality scores, then maybe your landing page isn’t relevant. Or maybe your ad copy needs to be tightened up. Creating new ad groups can be a way to deal with both issues.
Consider grouping by match type.
Sometimes it makes sense to group keywords by match type, to aid in keyword research and control cost per click by match type. I’ve found this especially effective for smaller accounts in niche markets where it’s hard to mine for new keywords simply by using search query reports. In larger accounts, grouping by match type just makes for unnecessary management time.
In fact, too many ad groups often become cumbersome to manage. Even a couple hundred ad groups can be super time consuming – I speak from experience on this. Single keyword ad groups (SKAGs) do make sense, but your entire account shouldn’t be full of them. You don’t want to end up in a situation like this:
This example is less about too many ad groups and more about an unreal number of negatives, but you get the point.
To me, the ideal number of keywords in an ad group is…. It depends. Surprise!
What’s your rule of thumb on number of keywords per ad group? Do you have a rule of thumb, or do you decide on the fly? Share in the comments!