How to write ad copy with AI for Facebook and Google: three versions and one fair test

You have an offer, a small budget, and an empty "primary text" box in Ads Manager. This guide shows how to write ad copy with AI for Facebook, Instagram and Google: one clear offer, three versions that open in different ways, and a fair test that shows which words bring enquiries. It covers the words of the ad, not budgets or targeting.

What you need

• One offer you can deliver this month, with its price or terms exactly as you charge them.
• Any good AI assistant, such as ChatGPT, Gemini or Claude.
• Meta Ads Manager, a Google Ads account, or both, already set up.
• Five to ten things customers really say, from WhatsApp, calls or reviews.
• An hour to write, and two weeks for the test.

Step 1: Write the offer card

AI writes good ads only from clear facts. Fill in this card first, and leave a line empty rather than guess.

Later, anything in an ad that is not on the card gets deleted.

Step 2: Collect the customer's words

Owners use trade words; customers describe their problem. Copy five to ten real lines from chats, calls and reviews, such as "the AC is running but the room is not cooling". Remove names, phone numbers and addresses first, and never paste customer lists or bills into an AI tool. Our guide on customer data and AI tools explains what is safe to share.

Step 3: Ask for three versions, each with one opening

Each version tests a different reason to reply: the problem, the offer, and trust. A prompt you can adapt:

You are helping a small Indian business write a Facebook and Instagram ad. My offer card: [paste your card] What customers say: [paste 5 to 10 lines, with no names or numbers] Write three versions. Version A opens with the customer's problem, version B with the offer, and version C with why they can trust us, using only the proof on my card. For each version, write two or three short sentences of primary text, where the first sentence works on its own, and a headline of up to six words. Use simple words a customer would use. Do not use "best", "No. 1", "guaranteed" or "100%". Do not say or hint that the reader has a health problem, money trouble or any other personal situation. No capital letters for emphasis. Keep every number exactly as I wrote it. Do not add anything that is not in my text.

If customers message you in Hindi or Hinglish, add one line: "Then write version A again in simple Hinglish, in English letters." Our guide on customer messages in Hindi and regional languages shows how to check it.

Step 4: Fit the words to each platform

Each platform puts your message into different boxes.

For Google, a prompt you can adapt. Twelve headlines are enough to start, and you can add more later up to Google's limit of 15:

Turn the three versions below into a Google responsive search ad: 12 headlines of 30 characters or fewer and 4 descriptions of 90 characters or fewer, with the character count after each line. Each headline must make sense on its own and next to any other. Use words a customer would type, such as [your service] in [your city]. No repeated words, phone numbers, symbols or capital letters for emphasis. Keep every number exactly as I wrote it. Do not add anything that is not in my text. [paste versions A, B and C]

AI tools often miscount characters, so check the length of each line yourself.

Example: a made-up AC service business in Jaipur

A made-up AC service business in Jaipur with four technicians wants more bookings before summer. Its card says: AC service at home with filter and coil cleaning and a gas pressure check, the price of any extra work told before starting, Jaipur only, in business since 2014, bookings on WhatsApp.

Version A, the problem:

"AC running but the room still warm? Our technician cleans the filter and coils at your home and checks the gas pressure. Book on WhatsApp."

Version B, the offer:

"Full AC service at home in Jaipur: filter and coil cleaning plus a gas pressure check. You hear the price of any extra work before we start."

Version C, trust:

"Servicing ACs across Jaipur since 2014. Our technicians explain any repair before doing it and give a written bill."

The AI's first draft called the business "Jaipur's most trusted AC experts" and promised "same-day visits". Neither was on the card, so the owner deleted both. For Google, lines such as "AC Service at Home in Jaipur" and "Gas Pressure Check Included" stayed, each under 30 characters.

Step 5: Check every line before it goes live

You answer the phone when a customer quotes the ad, so check each version:

• Every price, date and term matches the card.
• No claim you cannot prove, such as "best", "most trusted" or "guaranteed". The ASCI Code, India's self-regulation code for advertising, asks that ads be honest and truthful.
• On Facebook and Instagram, no line says or hints at the reader's health, money trouble, age or religion. "Struggling with back pain?" is the kind of line Meta does not allow; "Physiotherapy for back and neck pain" describes your service instead.
• Ads about jobs, housing or property, loans and other financial products, or social issues and politics need a Special Ad Category in Meta Ads Manager. Read its rules first.
• On Google, no phone number in the text, and no capitals, symbols or repeated words used for attention.
• Reviews and photos are real and shown with the customer's agreement. Never let AI write a "customer review".

For health, money, education or property claims, ask a lawyer if you are unsure; this guide is general information.

Step 6: Run a fair test

Change only the words. Keep the picture, audience, budget and dates the same.

• Facebook and Instagram: use the A/B test in Meta Ads Manager. Each version goes to a separate part of your audience, so nobody sees both, and Meta recommends the same budget for each. Test your two strongest versions and keep the third for the next round. Switching ads on and off by hand is not a fair test.
• Google: it already mixes your lines, so put the best headlines from all three versions into one ad. Judge the whole ad by enquiries, as Google advises, and use the asset report to replace a line that gets no impressions for several weeks.
• Count enquiries, not likes. Ask every new enquiry "Where did you see us?" and note it in a sheet with the date and the version.
• Fix the end date first, such as two weeks. Small budgets give small numbers; if two versions are close, keep the one that sounds like you and test a new idea.

Step 7: Keep the winner and write the next challenger

The winner stays and one new version tries to beat it. A prompt you can adapt:

This ad brought the most enquiries last month: [paste the winner] This one brought fewer: [paste the other] Write one new version with the same offer and facts that opens differently, for example with [a customer question / the season / what is included]. Keep every number exactly as I wrote it. Do not add anything that is not in my text.

Keep every round in the same sheet; over time it shows which words your customers answer.

Mistakes to avoid

• Opening with your name. "[Your shop name] welcomes you" tells a customer nothing; open with their problem or the offer.
• Changing three things at once. A new picture, text and audience together hide what worked; change one thing per round.
• Keeping extras the AI invented. Free installation or a discount you never planned becomes a promise; delete anything that is not on the card.
• Sending people to the wrong place. If the ad says "book on WhatsApp", the button should open WhatsApp, not your home page.

Common questions

Can ChatGPT write Facebook and Google ads?

Yes, it drafts them well from your offer, your prices and your customers' words. It does not know your business, so it fills gaps with guesses. Check every line against your offer card before the ad goes live.

Is Google Ads or Facebook better for a small business?

They do different jobs. Google search ads reach people typing your service into Google right now; Facebook and Instagram ads reach people who were not searching but may want it when they see it. Start where your customers already look, test small, and compare enquiries.

How long should the ad text be?

Google's limits are fixed: headlines of up to 30 characters and descriptions of up to 90. On Facebook and Instagram, put the whole message in the first sentence, because on a phone the rest may stay hidden until someone taps to read more.

Can I write my ad in Hindi or Hinglish?

Yes, write in the language your customers use when they message you or search for you. Have someone who speaks it daily read the AI's version aloud before it goes live, because AI translations can sound stiff.

Can Facebook or Google write the ad text for me?

Both can suggest or add ad text based on your own text and website. Meta reports results for the whole ad, so you will not see which suggested line worked, and Google lets you remove suggested lines you do not want. Check them like your own.

Next step

This week, fill in the card for one offer and run the Step 3 prompt; put nothing live before the Step 5 check. To reuse the winning words in posts, see a monthly content plan with AI, or take the free AI Business Checkup to see where AI fits next.