Aspect ratio
Aspect ratio is the proportional relationship between an image's width and height (for example 16:9 or 1:1). It defines the shape of the canvas and strongly influences composition.
Aspect ratio describes the shape of an image as a width-to-height ratio, independent of its actual pixel size. A 16:9 image is wide (landscape), a 9:16 image is tall (portrait), and 1:1 is a perfect square. You usually set it before generating because it shapes how the model composes the scene.
Common ratios and their uses
- 16:9 - YouTube thumbnails, video frames, widescreen banners.
- 1:1 - Instagram posts, avatars, product tiles.
- 4:5 / 9:16 - portrait social feeds, Stories, Reels and phone wallpapers.
- 3:2 / 4:3 - classic photography and print proportions.
Why it matters
The model is trained to compose for the canvas it is given, so picking the right ratio up front yields better framing than cropping later. If you already have an image in the wrong shape, outpainting can extend it to a new ratio without cutting off your subject.
Try it in the generator
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Related terms
- OutpaintingOutpainting extends an image beyond its original edges, generating new content that continues the scene - used to widen a crop, change the aspect ratio, or build out a larger composition.
- UpscalingUpscaling increases an image's resolution. AI upscalers do more than stretch pixels - they intelligently add believable detail so the larger image stays sharp.
- Text-to-imageText-to-image is the AI workflow where you type a written prompt and the model generates a brand-new image from it - no source image required.