How to Make an Instagram Post for Your Shop Using Just ChatGPT (Free, Step by Step)

You can turn one phone photo of your product into a finished Instagram post in about fifteen minutes using only the free version of ChatGPT: no design skills, no templates, no designer. This guide walks through the whole loop in order (prompt, fixes, sizes, caption, checks) with worked examples, and ends with how to tell whether the post actually helped your business.

Key takeaways

1. Give ChatGPT the real photo, your exact offer text in quotes, your business type and your colours. Vague requests such as “make it look nice” give generic results.
2. Expect two or three rounds of small fixes in plain English. That is normal, and still faster than waiting for a designer.
3. Read every word on the finished image. AI image tools can garble text, and a wrong price is a real cost to you.
4. Instagram accepts feed photos up to 1,080 pixels wide within a supported aspect ratio, so check the shape before you post.

Last reviewed 25 September 2026. Statements about Instagram were checked against Instagram’s Help Center on that date. Free plan limits on AI tools change often, so check what your own account currently allows.

What do you need before you open ChatGPT?

Three things you already have. First, a photo of the real product, even one taken on a counter with your phone. Second, exactly what you are offering: a price, a discount, a deadline, or simply “available today”. Third, your colours, or a mood if you do not know them, such as “warm and simple”.

Also decide the shape. Instagram’s Help Center says it uploads photos at the best quality possible up to a width of 1,080 pixels, keeps the original resolution of photos between 320 and 1,080 pixels wide when the aspect ratio is between 1.91:1 and 3:4, sizes larger photos down to 1,080 pixels, and crops photos outside a supported ratio (Instagram Help Center, retrieved 2026-09-25). A square image sits comfortably inside that range, so a square post is a safe default. Stories are a tall vertical format, and we cover that in the resize step below.

Step 1: What prompt should you type?

Upload the photo, then write something close to this, filling in the brackets with your real details:

“Turn this photo into a clean Instagram post for my [type of business]. Keep the product exactly as it looks in the photo. Add the text ‘[your offer]’ in a bold, easy-to-read font. Use [colours] as the background and accent colour. Square format for an Instagram feed post.”

Here is the same prompt filled in for a fictional candle shop: “Turn this photo into a clean Instagram post for my handmade candle shop. Keep the candle exactly as it looks in the photo. Add the text ‘Fresh batch today: 3 scents, pick up by 6pm’ in a bold, easy-to-read font. Use cream and forest green as the background and accent colours. Square format for an Instagram feed post.” The three details that matter are the business type, the offer text in quotes, and the format. Those are what stop the result being generic.

Step 2: How do you fix what comes back?

The first version is a draft. Describe what is wrong the way you would to a person, one change at a time so you can see what each change did:

• “Make the price text bigger.”
• “Use pink and cream instead of blue.”
• “Move the text to the bottom of the image.”
• “Keep everything the same but make the background plainer.”
• “The product looks different from my photo. Keep the product exactly as it is and change only the background.”

Two or three rounds is typical. If the result keeps drifting, start a new chat and paste the best version of your prompt instead of piling on corrections.

Step 3: How do you get the right size for each place?

A feed post, a Story and a WhatsApp Status image are different shapes. Ask for a resize in the same chat instead of starting again, so the product and offer stay the same:

Step 4: How do you write the caption and alt text in the same chat?

Stay in the conversation, because the AI already has the image and the offer in context. Ask for the caption and for alt text, which describes the image for people using screen readers:

“Write a short, friendly Instagram caption for this post in plain language. Mention that pick-up is by 6pm today, end with a clear call to action, and add three relevant hashtags. Then write one sentence of alt text describing the image.”

Example output (a fictional shop, generated with an AI assistant and lightly edited): “Fresh batch out of the pouring room this morning: three new scents, made in small runs, ready for pick-up by 6pm today. Message us to reserve yours before they are gone. #handmadecandles #smallbatch #shoplocal. Alt text: A cream candle jar with a green label on a wooden counter next to a small sign reading ‘Fresh batch today’.” Replace details in the example with your real ones, and only claim “before they are gone” if stock is genuinely limited.

What should you check before you post?

• Every word on the image. AI image tools can misspell or distort text, so read the price, the date and your business name letter by letter.
• The product itself. If the edited product no longer matches what you sell, the post is misleading. Ask for a fix or use your original photo.
• The offer. Prices, deadlines and stock claims must be true on the day.
• Your own photos. Use pictures of your real products, not generated images of items you did not make.

How do you tell whether the post worked?

Instagram lets you view insights for individual posts for any period within the past 90 days, as long as your account is public, either personal or professional (Instagram Help Center, retrieved 2026-09-25). After each post, write down the same three things in a notes app: how many people saw it, how many messaged or replied, and whether anyone mentioned it in the shop. Compare a few posts before you change your approach. One post is too small a sample to learn from.

When should you not use ChatGPT for a post?

For a big launch, a logo that must be exact, a regulated product such as food with allergen claims, or anything where a design error could mislead customers, get a person to check it or use a designer. AI is best at the everyday post that otherwise never gets made. Google’s own guidance on AI-generated content makes the same point about quality: using generative AI is not against its guidelines by itself, but generating many pages without adding value for users may violate its spam policy on scaled content abuse (Google Search Central, retrieved 2026-09-25).

What does a simple weekly routine look like?

The same photo can carry more than one post: see how to turn one product photo into three different Instagram posts. For a whole plan built around orders, read our home bakery plan, and for more ready-made prompts, use the free AI prompt swipe file. If you want the whole approach as a step-by-step course, Market Your Business With AI, our own course, is built around one reusable brief.

Frequently asked questions