What aspect ratio is best for Instagram?

Use 1:1 for a classic square feed post, 4:5 for a taller feed post that takes more screen space, and 9:16 for full-screen stories and reels covers.

Should I generate at the final ratio or crop later?

Generate at the final ratio. Cropping a finished image to a new shape often cuts off the part of the composition you cared about most.

Why does the same prompt look different at another ratio?

The model fills the canvas it is given, so a wider or taller frame changes how it composes the scene. Pick the ratio first, then reinforce framing in your prompt.

Basics · 4 min read

The Best Aspect Ratios for AI Images

Choosing the best aspect ratios for AI images sounds like a small decision, but it shapes the whole composition. The ratio tells the model how much room it has horizontally versus vertically, which changes how it frames a subject. Pick the ratio that matches where the image will live before you generate, because cropping a finished image to a different shape usually wastes the most important part. You can try every ratio for free on ImageGen.

Here is a practical map of which ratio to use for which job, and how the shape affects what the model produces.

Square (1:1) for social and avatars

A 1:1 square is the safe default for profile pictures, many social feed posts, and product thumbnails. It centers the subject and looks consistent in grids. If you are not sure where an image will be used, square is the least likely to need awkward cropping later.

Portrait (4:5 and 9:16) for phones and stories

Vertical ratios own the phone screen. 4:5 is the tall format that performs well in social feeds without getting cropped, and 9:16 fills full-screen stories and short-form vertical placements. Portrait ratios give more vertical room, which suits standing figures, tall objects, and scenes where you want sky or foreground above and below the subject.

Landscape (16:9 and 3:2) for banners and prints

Wide ratios fit website headers, slide backgrounds, video thumbnails, and YouTube covers at 16:9. The 3:2 ratio matches classic photography and standard print sizes. Landscape shapes invite wider compositions: establishing shots, scenery, and anything where horizontal space tells the story.

How ratio changes the composition

Because the model fills the canvas you give it, the same prompt produces different framing at different ratios. A portrait of a person at 9:16 leaves room for a full body; the same prompt at 1:1 crops to head and shoulders. Decide the ratio with the composition in mind, and mention framing in the prompt to reinforce it, for example "full-length shot" for a tall ratio or "close-up" for a square.

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Frequently asked questions

What aspect ratio is best for Instagram?: Use 1:1 for a classic square feed post, 4:5 for a taller feed post that takes more screen space, and 9:16 for full-screen stories and reels covers.
Should I generate at the final ratio or crop later?: Generate at the final ratio. Cropping a finished image to a new shape often cuts off the part of the composition you cared about most.
Why does the same prompt look different at another ratio?: The model fills the canvas it is given, so a wider or taller frame changes how it composes the scene. Pick the ratio first, then reinforce framing in your prompt.