Best aspect ratio and length for AI video
Aspect ratio is a distribution decision, not a taste decision. Pick it before you generate, because cropping a rendered clip afterwards throws away the framing the model composed for you.
Choose by where it will be seen
- 9:16 vertical — TikTok, Instagram Reels, YouTube Shorts, Stories
- 16:9 landscape — YouTube, websites, hero sections, display ads
- Posting to both? Generate twice rather than cropping once
Why cropping hurts AI video
The model composes the whole frame around your subject. Cropping a 16:9 render to vertical cuts the sides where the movement and light were built, and upscaling the remainder softens the detail that made it look filmic.
Clip length: short wins
Five to ten seconds is the sweet spot. Short generations hold subject consistency far better, render faster and match how social feeds actually consume video. If you need thirty seconds, make three tight clips and sequence them rather than asking for one long take.
- 5 seconds — hooks, loops, background plates
- 8 seconds — product reveals and single camera moves
- 10 seconds — establishing shots and atmosphere
Resolution and delivery
720p is plenty for feed playback, where video is compressed hard and watched on a phone. Keep the framing tight, favour a single camera move, and the clip will read as sharp regardless of the pixel count.
A simple workflow
Decide the platform, set the ratio, keep the clip under ten seconds, and generate two or three variations of the same prompt. Pick the steadiest one and post it — that is the whole loop.