TL;DR
- A responsive search ad takes 3-15 headlines of 30 characters and 2-4 descriptions of 90 characters, plus two optional 15-character display paths.
- Google shows up to 3 headlines and 2 descriptions at once; Headline 3 and Description 2 are not guaranteed to appear, even when pinned.
- Google states Ad Strength is not used for Ad Rank, Quality Score or auction wins and does not decide whether an ad can serve.
- An ad group can hold 3 enabled responsive search ads; Google recommends at least 2 with Good or Excellent Ad Strength.
- Ad customizers use {CUSTOMIZER.Name:default} with text, number, price or percent attributes, capped at 40 attributes per account.
Responsive search ads are the standard text ad format in Google Ads Search campaigns: you supply up to 15 headlines and up to 4 descriptions, and Google assembles them into different combinations for each search, testing which mix works best for the query, device and person searching. You need at least 3 headlines and 2 descriptions to publish one, headlines are limited to 30 characters, descriptions to 90, and the two optional display path fields to 15 characters each.
The rest of this guide covers how the assembly works, what pinning really does, why Ad Strength is not a performance score, how to read the asset and combinations reports, how many responsive search ads to run per ad group, when to use customizers and keyword insertion, and the mistakes that most often hold RSAs back. All limits and rules below match Google Ads Help as it reads in October 2026.
How responsive search ads assemble headlines and descriptions
An RSA is a set of parts, not a finished ad. You write a pool of headlines and descriptions; at auction time Google picks which ones to show and in what order. An ad can show up to 3 headlines and up to 2 descriptions, but Google may show fewer, for example on a narrow mobile screen. At least one headline and one description is always selected.
Because any headline can appear next to any other headline, and in any position, every asset has to make sense on its own and alongside the rest. A headline that only works as a follow-on to another ("And it ships free") breaks when it appears first. Headlines should not repeat each other either: if three of your fifteen say "Best Running Shoes Bangkok" with small variations, the system has fewer real options to choose from.
The final layout reads like this: up to three headlines separated by a divider, then the display URL (your domain plus up to two path fields), then up to two descriptions. Assets such as sitelinks, callouts and structured snippets can appear underneath.
The limits: 15 headlines, 4 descriptions, and character counts
Here are the numbers that matter when you build an RSA, as Google documents them:
| Element | Limit | Notes |
|---|---|---|
| Headlines | 3 to 15, 30 characters each | Up to 3 can show at once |
| Descriptions | 2 to 4, 90 characters each | Up to 2 can show at once |
| Display path | 2 fields, 15 characters each | Optional; shown after your domain |
| Enabled RSAs per ad group | 3 | Google recommends at least 2 with Good or Excellent Ad Strength |
| Ad customizer attributes | 40 per account | Types: text, number, price, percent |
Double-width characters (Chinese, Japanese and Korean) count as two characters each. Thai is not on that list, and Google does not document how Thai vowel and tone marks are counted; they are separate code points in Unicode, so check length in the editor rather than by eye. The live character counter in the ad editor is the authority; draft Thai headlines there, not in a spreadsheet that counts differently.
A practical way to fill 15 headlines without padding is to write them in groups of intent: four or five that contain the main keyword theme, three or four on benefits (speed, price structure, warranty, delivery area), two or three on proof you can actually back up (years in business, certifications, product range), two or three with a call to action, and one or two with your brand name. Descriptions then expand on the offer and give one clear next step each.
Pinning and its trade-off
Pinning fixes an asset to one position. Headlines have three positions (Headline 1, 2 and 3) and descriptions have two (Description 1 and 2). If you pin a single headline to Headline 1, only that headline can ever appear there.
Two details from Google's documentation are worth knowing before you pin:
- Headline 1, Headline 2 and Description 1 always show when something is pinned to them. Headline 3 and Description 2 are not guaranteed to show in every ad, so pinning a legal disclaimer to Headline 3 does not guarantee it appears.
- If you pin an asset to every position, your unpinned assets will never show.
The trade-off is control against combinations. Pinning one headline to position 1 removes every combination where another headline would lead. Google says pinning is not recommended for most advertisers and can lower Ad Strength. When you do need it, for a brand name in a regulated category or a required disclosure, Google advises pinning two or three assets to the same position, so the system still has a choice.
Worked example, illustrative only: a clinic must show its licence wording on every ad. Rather than pinning one headline to Headline 1, it writes three headlines that each include the required wording in different phrasing and pins all three to Headline 1. Positions 2 and 3 stay open to the other twelve headlines, so most of the testing survives.
Ad Strength vs performance
Ad Strength rates an RSA as Incomplete, Poor, Average, Good or Excellent. Google says it measures how well your creative combinations match the keywords in the ad group, and gives action items such as adding more headlines, making them more distinct, and including keywords.
Google also states that Ad Strength does not decide whether an ad is eligible to serve, and is not used to calculate Ad Rank, Quality Score or auction wins. It is feedback while you write. So an ad rated Average can outperform an ad rated Excellent in clicks and conversions, and you should judge ads on results.
That said, low Ad Strength is a useful warning about inputs. The usual causes are too few headlines, headlines that repeat the same words, keywords missing from headlines, and heavy pinning. Google also notes a keyword only counts toward Ad Strength if it fits entirely within one headline. Treat the rating as a checklist for the ad's raw material, and treat CTR, conversion rate and cost per conversion as the score.
Reading the asset report and combinations report
Ad-level statistics for an RSA are totals across all the combinations it served. To see inside the ad you need two reports:
- Asset report. Lists each headline and description with how often it served. Use it to spot assets that almost never show: Google is telling you it rarely prefers them. Replace those first, and keep the assets that serve often.
- Combinations report. Shows which headline and description combinations served most. Use it to check that the combinations people actually see read well together, and to catch odd pairings such as two headlines that say the same thing.
Do not swap assets every few days. Low-volume ad groups take weeks to gather enough impressions for a fair read. A steady rhythm (review monthly for most accounts, more often only where volume is high) gives cleaner signals.
How many responsive search ads per ad group
An ad group can have up to 3 enabled RSAs. Google's current guidance is to run at least 2 per ad group, each with Good or Excellent Ad Strength, and each with a unique final URL where that makes sense.
More ads do not mean more testing by themselves. Each RSA already tests combinations internally, so a second and third ad are best used to test a genuinely different idea: a different landing page, a different offer angle, or a version with pinning against one without. Three near-identical RSAs split impressions without teaching you anything.
Customizers and dynamic keyword insertion
RSAs support placeholders that fill in text at serving time.
Ad customizers
Ad customizers insert a value you define, such as a price, discount or stock count. You create a customizer attribute (text, number, price or percent), set values at account, campaign, ad group or keyword level, and reference it in a headline or description as {CUSTOMIZER.AttributeName:default text}. The most specific level wins. The default text shows when no value applies, so write it to read naturally on its own. Google documents customizers for headlines and descriptions.
Keyword insertion
Dynamic keyword insertion swaps in the keyword that triggered the ad, written as {KeyWord:default text}. If the keyword is too long to fit, the default text is used. It can raise relevance for long, specific keyword lists, but it can also produce awkward or misleading headlines when broad or phrase match triggers the ad on a search you would not phrase that way. Use it only in ad groups whose keywords all read well as headlines, and never with competitor brand terms.
Google also offers location insertion for RSAs and, in campaigns that opt in, text customization that generates extra assets from your landing page and existing ads. If you turn text customization on, review what it produces in the asset report as you would your own copy.
Common mistakes with responsive search ads
- Writing fewer than 15 headlines when you could write more. Fewer assets means fewer combinations to test. Aim for at least ten genuinely different headlines.
- Headlines that only work in sequence. Every headline must stand alone, because it may appear first, second or third.
- Pinning everything. Fully pinned RSAs behave like old fixed text ads and lose the reason to use the format.
- Chasing Excellent Ad Strength at the cost of message. Stuffing keywords into every headline to raise the rating can make the ad read worse.
- One RSA for unrelated keywords. If an ad group mixes themes, no set of headlines fits them all. Split the ad group first.
- Ignoring the landing page. Claims in headlines must match what the page says, or conversion rate suffers and policy reviews may flag the ad.
What this means for advertisers in Thailand
Where search terms mix Thai with English brand or product names, a bilingual asset pool makes sense: some headlines fully in Thai, some combining Thai with the English product name the market actually uses. Keep each headline in one coherent phrasing so mixed combinations still read naturally.
Watch Thai character counts closely, as noted above, and check how Thai headlines truncate on mobile. Where customizers insert prices, confirm the baht format and the default text read correctly in Thai. And when an account runs separate Thai and English campaigns, keep the RSA assets in the language of the campaign's targeting so Google is not choosing English headlines for Thai-language searches by accident.
FAQ
How many headlines and descriptions can a responsive search ad have?
A responsive search ad can have up to 15 headlines and up to 4 descriptions, with a minimum of 3 headlines and 2 descriptions. Headlines can be 30 characters and descriptions 90 characters, and up to 3 headlines and 2 descriptions show at once.
Does Ad Strength affect my Quality Score or Ad Rank?
No, Google states that Ad Strength is not used to calculate Ad Rank, Quality Score or auction wins, and it does not decide whether an ad can serve. It is guidance for writing better assets; judge ads on clicks, conversions and cost.
Should I pin headlines in responsive search ads?
Only when you must, such as for required legal wording or brand rules. Pinning reduces the combinations Google can test and can lower Ad Strength; if you pin, pin two or three alternatives to the same position.
How many responsive search ads should I run per ad group?
Run at least 2 and no more than 3, since 3 enabled RSAs is the per-ad-group limit. Make the extra ads test a different idea, such as another landing page or offer, rather than near-copies of the first.
Can I use responsive search ads in Thai?
Yes, responsive search ads work in Thai with the same limits. Draft Thai copy in the Google Ads editor so its live character counter shows the length Google actually counts.
If you would like an outside view on your search ads, the Google Ads management service covers asset writing and testing, and search campaign management covers structure and bidding. For retail accounts that also run Shopping, see Google Shopping ads.
