Writing ad copy for Google Ads is not like writing a headline for your website. You are not writing one ad. You are handing Google a pile of parts and letting it assemble the ad, thousands of times a day, in combinations you will never see individually. Ad copy that ignores that fact underperforms no matter how good the individual lines are.
This guide covers what the search ad format actually requires, the limits every line has to live inside, and how to write assets that hold up in any combination.
What Google Actually Does With Your Ad Copy
The standard search format is the responsive search ad. You supply up to 15 headlines and 4 descriptions, with a minimum of 3 headlines and 2 descriptions, and Google mixes and matches them against each individual search.
Two consequences follow, and both change how you write.
First, any headline can appear next to any other headline. Ad copy written as a sentence that continues from line one into line two will read as nonsense the moment the order changes. Every headline has to stand on its own.
Second, quantity is genuinely useful here in a way it usually is not. Google recommends at least 8 to 10 headlines, because more assets mean more combinations to test against real searches. Three headlines is the floor, not a strategy.
The Character Limits Every Line Lives Inside
- Headlines: up to 30 characters each, up to 15 of them.
- Descriptions: up to 90 characters each, up to 4 of them.
- Display path fields: up to 15 characters each.
Thirty characters is roughly four or five words. That constraint is the single biggest reason clever ad copy fails in search. There is no room for a setup and a payoff. Each headline gets one idea, stated plainly, and the ones that win are usually the ones that sound the least like advertising.
How to Write Ad Copy That Earns the Click
Start from the search, not from your brand
Google’s own guidance is to include your keywords in your headlines and to keep them relevant to what the person typed. Somebody searching “emergency plumber near me” is not looking for your company values. Ad copy that repeats their words back to them signals, in a fraction of a second, that they landed in the right place.
Write the first three as if they will appear together
This is Google’s recommendation and it is a useful discipline. Draft headlines one through three as a coherent trio, then make sure each still works alone. That gives you a strong likely combination without building a dependency you cannot control.
Make every asset genuinely different
Fifteen ways of saying the same thing gives Google nothing to test. Spread your ad copy across distinct angles: what you do, who you serve, what makes you different, proof, service area, response time, and the action you want. When two headlines are near-duplicates, one of them is wasted inventory.
Be specific enough to be checkable
“Great service” is invisible. “Same-day service, 7 days” is not. Specific claims outperform generic ones, and they carry a second benefit: a claim you can actually back up keeps you clear of the accuracy problems that get ads disapproved or land businesses in trouble with regulators.
Match the ad copy to the landing page
If the headline promises a free estimate and the landing page opens with a general services overview, the click is wasted. The page has to repeat the promise the ad made, near the top, in similar words.
Ad Strength, and What It Is Really Telling You
Google scores each responsive search ad with an Ad Strength rating from Poor to Excellent. It measures whether you have supplied enough distinct, relevant assets, not whether your writing is good.
Google reports that advertisers who move an ad from Poor to Excellent see 15% more clicks and conversions on average, and recommends running at least two ads with Good or Excellent strength in every ad group. Treat the rating as a completeness check on your ad copy, not a verdict on it.
One setting deserves a warning. Pinning locks a headline or description to a fixed position, and Google states plainly that pinning is not recommended for most advertisers and can reduce ad strength, because it collapses the number of combinations available. Pin only when a line is legally or factually required in a specific slot.
Ad Copy Mistakes That Quietly Cost You Clicks
- One ad per campaign. A single ad group with a single ad gives the system nothing to compare.
- The same ad copy in every ad group. If the ad groups are targeting different searches, identical text means most of them are irrelevant to most of the traffic.
- Headlines that need each other. Sentences broken across two assets read as gibberish in the wrong order.
- Pinning everything. Full control over placement means the format cannot do the one thing it is good at.
- Writing once and never revisiting. Ad copy ages with your offers and your competitors. Review it quarterly.
Frequently Asked Questions About Google Ads Ad Copy
How many headlines should I write?
Google allows up to 15 headlines and recommends at least 8 to 10. More distinct assets give the system more combinations to test against real searches. Only stop early if you genuinely cannot write another headline that says something new about the offer.
What are the character limits for headlines and descriptions?
Headlines allow up to 30 characters each and descriptions allow up to 90. Display path fields allow 15 characters each. Write to the limit rather than under it, since truncated space is wasted space, but never pad a line just to fill it.
Should I pin headlines to specific positions?
Usually no. Google says pinning is not recommended for most advertisers and can lower ad strength, because it removes combinations from the pool. Reserve pinning for text that has to appear in a fixed position for legal or compliance reasons.
Does ad copy affect Quality Score?
Yes, indirectly and significantly. Expected click-through rate and ad relevance are both components of Quality Score, and both are driven by how closely your ad copy matches the search. Better-matched ad copy improves the score, which improves your position and efficiency.
Can I use AI to write my ad copy?
For first drafts and volume, yes, and it solves the blank-page problem of writing fifteen headlines. Every line still needs a human check for accuracy, because you are legally responsible for claims in your ads, and generated copy tends toward generic phrasing that all your competitors are also running.
Get More From the Budget You Are Already Spending
Ad copy is one lever among several, and the rest are covered in our guide to paid advertising for small business. Since ad relevance feeds directly into Quality Score, that guide is the natural next read, and pairing better copy with a clean negative keyword list stops you paying for searches that were never going to convert. If you would rather hand the account to someone who does this daily, that is what our paid advertising service is for, and you can tell us what is not converting and we will start with the copy and the search terms report. For more guides like this one, subscribe to the Demur Design newsletter in the footer below.
This article is researched and drafted with AI, then reviewed, fact-checked, and published by Demur Design.
Sources
- About responsive search ads (Google Ads Help)
- Best practices for creating effective Search ads (Google Ads Help)
- About Ad Strength for responsive search ads (Google Ads Help)
