What aspect ratio should I use for Instagram?

4:5 for feed posts, because it occupies the most vertical space the feed allows. 1:1 is safe everywhere, and 9:16 suits stories and reels.

Should I choose the ratio before or after generating?

Before. The model composes for the frame it is given, so cropping afterwards discards arrangement it made deliberately.

What is the difference between aspect ratio and resolution?

Ratio is shape, resolution is size. 1:1 describes a square; 1024x1024 describes a specific square. Two images can share a ratio and differ enormously in resolution.

Which ratio looks most like a photograph?

3:2, because it matches 35mm film and most digital camera sensors. 4:3 reads as older digital or medium format.

Can I change aspect ratio without cropping?

Yes — outpainting generates new content beyond the original edges, which extends the frame rather than cutting into it.

What ratio do print sizes use?

They vary and rarely match screen ratios. 6x4 inches is 3:2, 8x10 is 4:5, 5x7 is close to 5:7. Decide the print size before you crop.

AI image glossary

What is aspect ratio?

The proportional relationship between an image’s width and height, such as 1:1, 4:5 or 16:9. Chosen before generating, because the model composes for the frame.

Aspect ratio is the proportion between an image’s width and its height, written as two numbers such as 1:1, 4:5 or 16:9. It describes shape rather than size, so a 1:1 image is square whether it is 100 or 4000 pixels across.

Three empty paper frames — square, tall and wide — overlapping on warm paper

The model composes for the frame you give it

Generate 16:9 and the scene is arranged horizontally; generate 4:5 and the same subject is rearranged vertically. Cropping a wide result to a tall one afterwards discards composition the model deliberately made, which is why the ratio is a decision before generation rather than after.

The ratios that actually matter

Square for marketplace listings and profile images. 4:5 for portrait-orientation social posts, because it occupies the most vertical space most feeds allow. 16:9 for thumbnails and banners. 3:2 when you want the image to read as a photograph, since it matches 35mm film.

Print uses a different set entirely

Six by four inches is 3:2, eight by ten is 4:5, and five by seven is close to 5:7. A photograph composed for a screen ratio and printed at a paper one loses its edges, so print size belongs in the decision before any cropping happens.

When a destination demands both shape and size

Crop for shape first and resize for pixels second. Doing it the other way round usually decentres the subject, because the crop then has to fight a dimension that was already fixed.

Aspect ratio at a glance

Describes: Shape, not size
Social feed: 4:5 portrait
Thumbnail or banner: 16:9
Reads as a photograph: 3:2
Marketplace or avatar: 1:1
Decide it: Before generating

Related terms

What aspect ratio sits next to

What is outpainting?Change shape without cropping.

image cropperCrop to an exact ratio, free.

resize an imageHit an exact pixel target.

UK passport photo sizeWhere the ratio is dictated.

browse real promptsEvery card lists its ratio.

AI Image GlossaryEvery term, defined.

Put it to use

Where this choice appears

generate from a descriptionThe main generator — text to finished image.Open Prompt Gallery120 images with the exact prompts that made them.Open start from a photoStart from a picture you already have.Open AI Photo EditorChange part of a photo, keep the rest.Open upscale to 4KEnlarge to 4K without the smearing.Open restore an old photoExposure, noise and old-photo restoration.Open remove something from a photoMasked removal that rebuilds the background.Open blur a photo backgroundDepth-aware, not a uniform filter.Open colourise black and whitePlausible colour for black and white.Open AI Logo GeneratorMarks that still read at 16 pixels.Open tattoo flash designsDesigns that survive being tattooed.Open generate illustrationIllustration and painting, not photographs.Open generate a headshotStudio-grade portraits without a studio.Open the photo specificationThe exact specification, and how to meet it.Open restyle a roomRestyle a room you can photograph.Open the glossarySeed, denoise, inpainting, explained.Open

Aspect ratio — questions people ask

What aspect ratio should I use for Instagram?: 4:5 for feed posts, because it occupies the most vertical space the feed allows. 1:1 is safe everywhere, and 9:16 suits stories and reels.
Should I choose the ratio before or after generating?: Before. The model composes for the frame it is given, so cropping afterwards discards arrangement it made deliberately.
What is the difference between aspect ratio and resolution?: Ratio is shape, resolution is size. 1:1 describes a square; 1024x1024 describes a specific square. Two images can share a ratio and differ enormously in resolution.
Which ratio looks most like a photograph?: 3:2, because it matches 35mm film and most digital camera sensors. 4:3 reads as older digital or medium format.
Can I change aspect ratio without cropping?: Yes — outpainting generates new content beyond the original edges, which extends the frame rather than cutting into it.
What ratio do print sizes use?: They vary and rarely match screen ratios. 6x4 inches is 3:2, 8x10 is 4:5, 5x7 is close to 5:7. Decide the print size before you crop.

Related AI image terms

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