In this post, I’ll explain the dizzying versatility of Google’s RSA (Responsive Search Ads), some of the main reasons why they are so powerful and why you would be crazy not to use them.
What are responsive search ads?
Responsive search ads are one format of paid for (pay-per-click) text ads that can appear in Google’s search results on mobile, desktop or tablet devices. When creating an ad, you can enter up to 15 headlines and up to 4 descriptions. Google Ads then combines different headlines with different descriptions to create the ad that is shown. You don’t have to enter that many but the more you add, the better chance you give Google Ads of creating an ad that matches the user search query, context and intent. Up to 3 of the 15 maximum possible headlines can be combined with up to 2 of the 4 maximum number of descriptions when the ad is displayed. There aren’t always 3 headlines shown and neither are there always 2 descriptions shown. These are the maxima. Headlines can be up to 30 characters each and descriptions up to 90 characters each.
Google Ads tests different ad combinations over time and, using its machine learning technology, can begin to show the better performing ads more often.
How many possible ad combinations are there?
Soon after starting to use RSA, I pretty quickly noticed an improvement in the performance of some of my campaigns. I really wanted to dig into that to get a better understanding of why.
I calculated that the maximum number of ways that you can combine any 3 of 15 headlines (h1, h2, …, h15) in any order, with no repeats, together with any 2 of 4 descriptions (d1, d2, d3, d4) resulted in a theoretical maximum of 32,760 possible ads. All from 1 ad set-up. That provides staggering versatility. Anybody that wants to understand how I arrived at that number can jump to my calculation and then come back and carry on reading from here. If you think I’ve got the number wrong, please tell me in the comments section. In any order means that h1+h2 is considered a different combination from h2+h1. No repeats means that h1+h1 is not a possible combination, for obvious reasons.
I say theoretical maximum number of combinations because there are practical reasons why not all possible combinations would be used by Google Ads. For example, if 2 headlines were very similar, Google Ads may be less likely to show them at the same time. Also, if 1 headline were stronger than another, then the weaker headline may have a lesser chance of being shown. You can also fix some of your headlines and descriptions to certain positions in the ad by ‘pinning’ them when you create the ad. This clearly restricts the combinations that Google Ads can create so is not recommended unless there are exceptional circumstances.
Here’s a video tutorial from Google
Benefits of responsive search ads
- Time savings. There is a bit more work involved in setting up each RSA but in reality you’re saving lots of time by creating huge numbers of possible ad combinations.
- Increased likelihood of one of your ads showing.
- Increased likelihood of better ad performance, ROI, etc.
Google’s ad strength tool
Google’s ad strength tool gives you a score as you are creating the ad to help you optimise it. Tips like “add more headlines”, “make your headlines more unique” and “include popular keywords in your headlines” help you to create an ad that will get off to a flying start. Of course, you can always come back and edit your ad to improve it, after you have some transaction data. A preview of how your ad might actually appear is also provided and you can opt to use the ad preview for desktop or mobile display.
How to see which ad components have been shown most?
Once your ads have been running for a while, you can see exactly how many times each headline and description has been shown by viewing “asset details”. I have found that some headlines and descriptions don’t get shown at all and others grab the lion’s share of exposure. That helps to know where to improve my ads.
Best practice for creating ads
- Google recommends creating at least 1 RSA in each ad group and at least 2 expanded text ads to provide the maximum chance of a good ad showing.
- Make maximum use of the number of headlines and descriptions available.
- Test diverse headlines and descriptions, review performance and optimise the ad based on data history.
- Use the ad strength tool.
- Other best practices as with all text ads i.e. include CTAs, USPs, offers etc.
Do responsive search ads always perform better?
The answer is always to rely on actual data. They may not perform better under certain circumstances so the only way to find out is to test different ads. They may perform better in certain respects such as CTR (click through rate), number of clicks or CPC (cost per click) but those measures are irrelevant if your conversion actions are online sales, where ROAS (return on ad spend) or conversion value are better KPIs.
Here’s how I arrived at the figure of 32,760.
Ways of combining 2 headlines. Any 2 of 15 headlines (h1, h2, …, h15) can be combined (in any order, with no repeats) as follows, dealing with h1 first and then working through the rest.
- h1+h2, h1+h3, …, h1+h15 = 14.
- h2+h1, h2+h3, …, h2+h15 = 14.
- and so on … until
- h15+h1, h15+h2, …, h15+h14 = 14.
- Total = 15 * 14 = 210.
- Notably this number can also be arrived at by using 15 * 15 – 15
Ways of combining 3 headlines. Any third headline out of the 15 could be combined with any of the above 210 combinations involving 2 headlines i.e. 210 * 15 = 3,150 ways but that would include repeats which we need to deduct.
The number of repeats in the 3,150 is as follows.
- h1 combined with the 14 h1s in row 1 above and the h1s in rows 2 thru 4 (= 14 + 14 = 28).
- h2 combined with the 14 h2s in row 2 above and the h2s in row 1 and 3 thru 4 (= 14 + 14 = 28).
- and so on … until
- h15 combined with the 14 h15s in row 4 above and the h15s in row 1 thru 3 (= 14 + 14 = 28).
- Total = 15 * 28 = 420 repeats.
- Notably this number can also be arrived at by using 15 * (15 – 1) * 2.
Ways of combining 3 out of 15 headlines with no repeats, therefore = 3,150 – 420 = 2,730 ways. This number can also be arrived at by the formula 15 * (15 * 15 – 15) – 15 * (15 – 1) * 2.
The advantage of the final formula above is that it could be used for the general case to calculate the number of possible combinations of 3 out of ‘n’ headlines by using n * (n * n – n) – n * (n – 1) * 2.
For example, if Google changed the number of allowable headlines from 15 to 20, we would know that the number of ways of combining 3 out of 20 would be 20 * (20 * 20 – 20) – 20 * (20 – 1) * 2 = 6,840 combinations.
Now we have to deal with the descriptions (d1, d2, d3, d4) which is much simpler.
- d1+d2, d1+d3, d1+d4 = 3 ways.
- d2+d1, d2+d3, d2+d4 = 3 ways.
- d3+d1, d3+d2, d3+d4 = 3 ways.
- d4+d1, d4+d2, d4+d3 = 3 ways.
- Total = 12 ways.
So, 2,730 possible headline combinations combined with 12 possible description combinations makes a total theoretical possible number of ad combinations of 2,730 * 12 = 32,760.
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