AI Image Generator for Instagram & Facebook: Prompts That Work

The best way to use an AI image generator for Instagram and Facebook posts is to treat it like a photographer, not a designer. Let the AI make the picture: the product on a table, the plate of momos, the hotel balcony at sunrise. Then add your headline, price and logo yourself in a design tool. AI still gets lettering and logos wrong often enough that you shouldn't hand it either job.

Below you'll find prompts that work for common business posts, the sizes Meta's own help pages give for each placement, what Meta's AI labels mean for a small business, and which tools are worth opening. Read it once, save the prompt table, and you'll spend far less time rerolling images that almost work.

How to get on-brand pictures from an AI image generator

The gap between a generic AI picture and one that looks like your brand is almost all in the prompt. Vague prompts get stock-photo mush. Specific prompts get something you'd actually post. A prompt that works has six parts:

1. Subject: what's in the frame, in detail. "A ceramic cup of milk tea with cardamom pods beside it", not "tea".

2. Setting: where it is. "On a wooden café table by a window".

3. Light: "soft morning daylight", "warm lamp light in the evening", "bright studio light".

4. Style: "realistic product photo, shallow depth of field" or "flat illustration, two colours".

5. Composition: "subject on the right third, plain space on the left for text".

6. Brand colours: "props and background in deep green and cream".

Write it as one or two plain sentences. Then keep a short "prompt recipe" in a note: your usual light, style and colours. Each time you need an image, swap only the subject. That one habit does more for a consistent feed than any choice of tool.

Prompts by use case (copy, then change the details)

These starters cover the posts most small businesses publish every month. Replace the bracketed parts and add your colours and light from your recipe.

Two warnings from experience. First, don't let AI invent your actual product if people will receive the real thing. It'll get the shape, label or colour slightly wrong, and customers notice. Use a real photo of the product and let AI make the background around it or extend the frame. Second, food and rooms should look like what you serve and rent. A Pokhara hotel that posts an AI suite twice the size of its real rooms will hear about it in reviews.

For more ways to use AI across your content, not just images, see our guide to AI for social media content.

Instagram and Facebook image sizes for each placement

Instagram's help center says photos upload at up to 1080 pixels wide and keep their resolution when the aspect ratio sits between 1.91:1 (wide) and 4:5 (tall). Anything outside that range gets cropped. Meta's ads guide recommends 4:5 at 1440 x 1800 for Facebook and Instagram feed image ads, and 9:16 at 1440 x 2560 for Stories.

We'd default to 4:5 for both feeds. It fills more of a phone screen than a square and posts on both apps without cropping. Most AI tools let you choose the ratio before you generate. Do it there, because cropping a square into 4:5 later can slice off the top of your subject.

For Stories, Meta's ads guide says to keep text, logos and key elements out of roughly the top 14% and bottom 35% of the frame, plus 6% on each side, where the profile icon and buttons sit. Tell the AI to put the subject in the middle and keep the top and bottom plain. If you're unsure about character counts for the caption that goes with it, our character limits table has every network in one place.

Add text and your logo after you generate

Image models have improved at lettering, but they still misspell words, invent letters and warp logos. Your price, date and brand name are the parts of a post that must be exactly right, so put them on yourself. If you post in Nepali, you'll want proper Devanagari fonts for that text anyway.

1. Generate the image at the ratio you'll post (4:5 for feeds, 9:16 for Stories).

2. Open it in a designer with your Brand Kit loaded: logo, colours and fonts.

3. Add a headline of seven words or fewer in your brand font.

4. Put your logo in the same corner on every post. Small is fine.

5. Check it on your phone at arm's length. If you can't read it in two seconds, cut words or add contrast.

6. Export at the size from the table above and write the caption.

AI labels and disclosure on Instagram and Facebook

Meta's help center says AI-created or AI-modified content may be identified and labelled across its apps, partly by reading industry-standard signals that some AI tools add to files. It may require you to label photorealistic video or realistic-sounding audio that was digitally created or altered, but labels are not required for images. Meta can still put a label on an image if its systems detect AI generation or editing.

In practice, a still post doesn't need you to tick a box, but it may show "AI info" anyway if your tool embeds those signals. We think that's fine. What damages trust is passing off a generated image as something real. Our rules of thumb:

Don't use AI images to show customer results, before-and-after photos or reviews.

Don't show premises, rooms or dishes that look better than the real ones.

Do say it's AI-made if a follower asks. A one-line reply is enough.

If you post a Reel or video with realistic AI footage or a cloned voice, add the label. Meta says there may be penalties for content shared without a label when one is required.

Which AI image generator to use

You don't need five subscriptions. The right AI image generator for Instagram and Facebook posts is the one that fits where you already design and schedule. Here's how the common choices compare, based on each company's own pages.

Our honest take: if you already design in Canva and post a few times a week, try its built-in tools before adding anything. If commercial safety matters to a client, Adobe's statement about how Firefly models are trained is the clearest of the group. If you want the image, the text overlay and the scheduled post to live in the same place, that's what we built GoBrandIt for.

Making AI post images in GoBrandIt

AI image generation is included on the Creator plan and up. You describe the picture, pick the size, and open it in Social Designer, which has your Brand Kit (logo, colours, fonts), Nepali (Devanagari) type and 300+ templates. Paid plans with AI images can also edit a photo with AI, remove a background or expand the frame. When it looks right, "Use in post" drops it into the composer, where you write the caption with the AI assistant in your Brand Voice and schedule it to Instagram, Facebook and your other accounts.

AI work is paid for in credits: 1 credit equals 1,000 tokens of AI work. A short caption costs under 1 credit and an image costs more. Creator includes 300 credits a month and Business includes 1,000, and you can buy extra packs that never expire. See the pricing page for the full plan list, then read how to schedule Instagram posts to get the image out on time.

Frequently asked questions

Can I use AI-generated images on Instagram and Facebook?

Yes. Meta allows AI images and doesn't require a label on still images, though it may add an "AI info" label if it detects AI signals. Avoid using them to show fake results, reviews or products you don't sell.

Do I have to label AI images on Facebook?

Not for still images, according to Meta's help center. Meta may require a label for photorealistic video or realistic-sounding audio, and may label an image itself if its systems detect AI.

What size should an AI image be for an Instagram post?

Generate at 4:5 and export at 1080 x 1350 pixels. Instagram keeps photos between 1.91:1 and 4:5 at up to 1080 pixels wide, so 4:5 is the tallest feed image you can post without cropping.

Is there a free AI image generator for social media posts?

Yes. Adobe Firefly offers free daily generations and ChatGPT's free tier includes image generation with limits. Canva's free plan has an AI allowance too; check its pricing page for the current limit.

Why does AI get the text in my image wrong?

Image models draw letters as shapes, so spelling, prices and logos can come out garbled. Generate the picture without text, then add your words and logo in a design tool.

Sources: Instagram Help Center: photo resolution and aspect ratios · Meta Ads Guide: Instagram Feed image specs · Meta Ads Guide: Facebook Feed image specs · Meta Ads Guide: Instagram Stories image specs and safe zones · Meta Help: How to identify AI content on Meta products · Adobe Firefly plans and FAQ · OpenAI: ChatGPT Free Tier FAQ. Prices and features checked October 2026. Tools change their plans often, so confirm on their own pricing page before you buy.