16:9, 9:16, or 1:1: choosing a shape before you generate

Aspect ratio is not a post-processing crop. It changes what the model has room to compose, so it belongs at the start of the job, not in the editor afterwards.

16:9 for depth

Landscape gives you horizontal room: dolly moves, wide establishing shots, anything that reads as a scene. It is the default for web embeds and YouTube, and it is the shape most training data uses, which makes it the most predictable choice.

9:16 for a single subject

Vertical compresses the frame around whatever is centred. It suits a product rotating, a face, or a texture — one thing filling the frame. Wide vistas collapse into noise. If the idea needs context around the subject, vertical will fight you.

1:1 for feeds

Square survives both feed layouts and reads as deliberate. It is the safest choice when the same clip will be reused in several places.

Plan the cut first

Generating vertical and cropping to square wastes the top and bottom of your output. Decide the final placement, generate in that shape, and only then consider a second render for a different platform.