You shoot a 16:9 video and need to post it on TikTok (9:16), Reels (4:5), and YouTube Shorts (9:16). Manual cropping each takes 30–45 minutes. AI auto-aspect-ratio does this in minutes — but there's something important to know first.
Important: AI auto-aspect-ratio is a draft — you still need to review every frame before publishing. AI can crop the wrong subject, cut off faces, or remove important on-screen text.
Aspect ratios you need to know
| Platform | Recommended ratio | Notes |
|---|---|---|
| TikTok | 9:16 (portrait) | Full mobile screen |
| Instagram Reels | 9:16 or 4:5 | 4:5 for feed, 9:16 for full Reels |
| YouTube Shorts | 9:16 (portrait) | Full mobile display |
| Instagram Feed | 4:5 or 1:1 | 1:1 for square grid |
| YouTube / Facebook Video | 16:9 (landscape) | Standard |
How AI auto-aspect-ratio works
AI tools use object tracking to identify the main subject (usually a person), then automatically crop the frame to keep that subject visible as the aspect ratio changes. This technique is called smart crop or auto-reframe.
Popular tools with this feature
- Adobe Premiere Pro — Auto Reframe (built-in, subscription required)
- DaVinci Resolve — Smart Reframe (Studio version)
- CapCut — Auto crop for each ratio (free, popular with Vietnamese creators)
- Various online AI tools with similar functionality
Practical workflow: AI crop + manual review
- Download your source video (use Klypio YouTube Downloader or TikTok Downloader if needed)
- Run AI auto-reframe for the target ratio
- Review key frames manually: intro, outro, frames with text/logo, scenes with multiple people
- Manually adjust frames the AI cropped incorrectly
- Export and post
Where AI commonly gets it wrong:
- Scenes with multiple people — AI struggles to pick the main subject
- Important text overlays cropped outside the frame
- Fast cuts — AI lags tracking the subject
- Product demo shots — AI follows the face, not the product
See also: AI auto-crop for vertical/horizontal/square formats and viewer retention YouTube vs TikTok guide. Manage your cropped clip library at Klypio app.