Responsive Search Ads (RSAs) are the standard text ad format in Google Ads. Instead of writing a single fixed ad, you provide up to 15 headlines and 4 descriptions. Google automatically tests different combinations and learns which pairings perform best for each query, device, and user context. At any given moment, Google shows at most 3 headlines and 2 descriptions, but can draw from hundreds of possible combinations to find the highest-performing variation.
RSAs replaced Expanded Text Ads (ETAs) as the default ad format in 2022. Unlike ETAs, which had fixed headline and description positions, RSAs allow Google to reorder headlines and mix descriptions dynamically. This means your most important message should be pinned to a specific position if it must always appear. Otherwise Google may show it less frequently if other combinations test better.
Each RSA headline is limited to 30 characters. Each description is limited to 90 characters. Google requires a minimum of 3 headlines and 2 descriptions for an RSA to be eligible to run, but you should fill all 15 headline slots and all 4 description slots to maximize the combination pool Google has to work with. More varied, thematically diverse assets improve your Ad Strength rating and give the automated system more material for testing.
Avoid writing headlines that only make sense when shown together. Since Google may display any combination of 1–3 headlines, each headline should be able to stand on its own. This tool's preview mode shows you how different combinations look at full size on both desktop and mobile, so you can catch awkward pairings before launching.
Ad Strength is Google's rating of how well your RSA assets cover different themes and queries. It runs from Poor to Excellent and is primarily based on the number of unique headlines and descriptions, the diversity of messaging across those assets, and relevance to your target keywords. Google recommends achieving "Good" or "Excellent" Ad Strength across all RSAs in an account.
Ad Strength does not directly determine auction eligibility or Ad Rank. A "Poor" RSA can still win auctions and drive conversions, especially if it has highly relevant copy for a specific query. Ad Strength is a signal for optimization, not a quality score with direct auction consequences. Don't sacrifice specific, high-intent messaging just to hit "Excellent" by adding generic variants.
Pinning forces a specific asset to always appear in a set position. For example, pin your brand name to Headline 1 so it's always the first thing shown. Google allows pinning to positions 1, 2, or 3 for headlines and position 1 or 2 for descriptions. Pinning reduces the combination pool, which may lower Ad Strength, but it gives you control over required messaging for legal compliance, branding, or promotional offers.
Use pinning selectively. Pinning every asset effectively turns your RSA into a fixed ad and eliminates the testing benefit. Best practice is to pin only what's legally or brand-required, and leave the remaining asset slots unpinned so Google can optimize the rest.