PROMPT GUIDE

How to make blog featured images with AI (OGP ratio and margins)

A featured image is the face of a blog post in post lists and when shared on social media. It gets cropped differently depending on your blog theme and the social network, so the composition has to work wherever it is cut. This guide covers ratios and framing that suit featured images, how to choose a picture that fits the post, and example prompts.

Last updated: 2026-10-22 approx. 3 min read

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The short answer

When making a blog featured image (eye-catch) with AI, generate it at the wide ratio shown when the post is shared on social media (the OGP image), place the subject in the center and leave a little space around it. Keep text and faces away from the edges so they survive cropping. A picture that shows the post's content as one scene tells readers what the post is about even in a list.

How do you make a blog featured image with AI?

Match the wide ratio used when posts are shared, put the subject in the center and keep important things away from the edges.

When you share a blog post on social media, it shows as an OGP image at a set wide ratio. The ratio and recommended size differ by social network and blog service and can change, so check the official guidance of the services you use. A wide ratio around 1.91:1 is commonly used. With AI, generating around 16:9 and trimming the top and bottom slightly is easy to work with.

Words that suit featured images

Tag	Meaning	Note
`centered`	Centered	The subject survives edge cropping
`wide shot`	A wide shot	Conveys the scene Details
`simple background`	A simple background	Easy to put text on Details
`flat illustration`	A flat illustration	Blends well with a blog
`soft pastel colors`	Soft colors	Does not clash in post lists
`no text`	No text	Add the title later

Soft wide scenery of hills and sky with no people, a versatile blog header image — 風景だけの見出し画像

Illustration usage rules

What are the steps to make a featured image?

Steps to make a blog featured image with AI

Check the recommended OGP ratio and size for your blog and social networks in their official guidance
Turn the post's content into one scene (for example working on a laptop, studying in a cafe)
Make several wide images with the subject centered and space around it
Crop to the recommended ratio and check how it looks on social media with a crop simulator
If you add text, put it large near the center (the edges may be cut)
Compress to WebP or JPEG so the page stays light before setting it on the post

1girl, solo, sitting at a desk, laptop, smile, indoors, room, window, soft lighting, wide shot, centered, simple background, soft pastel colors, no text

a wide flat illustration of an anime girl studying with a notebook in a cozy cafe, centered in the frame, plenty of calm space around her, soft pastel colors, no letters or signs

How do you choose a picture that fits the post?

Turn the post's content into one scene of who is doing what and where, and the picture will convey what the post is about.

Type of post	Example scene	Example words
How-to, explanations	Working on a laptop	laptop, desk, focused
Study notes, summaries	Writing in a notebook, reading a book	notebook, reading, library
Travel, outings	Seen from behind looking at the view	from behind, scenery, wide shot
News, diary	Waving with a smile	waving, smile, looking at viewer
Seasonal topics	Seasonal items and scenery	cherry blossoms, autumn leaves, snow

Rinka's tips

Keeping the same style and layout across your post list gives the whole blog a unified look
Put faces slightly above center; the bottom may be covered by the title band in post lists
Naming the image file with English words describing the content helps it get found in image search

To add a watermark or site name to a featured image: How to Add a Watermark to Images, with Tips for Social Media →

What are the common featured image mistakes and fixes?

Problem	Cause	Fix
The face or text gets cut on social media	Placed near the edge	Center the subject and text, and write centered
It is unclear what the post is about	The scene has nothing to do with the post	Ask for one scene based on the post's content
The image is heavy and the page is slow	A large PNG left as is	Convert to WebP or JPEG at about 1200 pixels wide
Meaningless text appears	Objects that attract text (signs, book covers)	Add no text
The style differs from post to post	Different wording each time	Fix the style and color words in a set line

What should you watch when using featured images?

Check the generation service's terms to see whether you may use images on blogs or posts with ads. Rules can change.

Do not use images that imitate real people, brands or other people's characters
Write a description of the picture in the image's alt text, not a list of prompt words
Keep the original at a large size and shrink only the copy used in the post

To make video thumbnails: How to make YouTube thumbnails with AI (16:9 and space for text) →

To make an X header image: How to make an X (formerly Twitter) header image with AI →

Final checks before publishing or posting: The Complete Pre-Posting Checklist for AI Art →

FAQ

Frequently Asked Questions

What ratio should a featured image be?

Matching the OGP image ratio used when posts are shared is recommended; a wide ratio around 1.91:1 is common. It differs by service and can change, so check the official guidance.

Should I put text on a featured image?

If you do, place it large near the center and avoid the edges, which may be cut. Adding the text later rather than having the AI draw it is more reliable.

My featured image is heavy and slows the page.

Convert it to WebP or JPEG and shrink it to about 1200 pixels wide. You can also use a tool that converts it in the browser.

Can I use AI images on my blog?

It depends on the terms of the generation service you used. Check the official terms, including whether they may be used on posts with ads or on commercial blogs.