Quick Answer: Use 9:16 vertical for TikTok, Reels, Shorts and Stories; 1:1 square for feed posts that must work everywhere; 16:9 horizontal for YouTube and desktop. If you only produce one format, produce 9:16 — it dominates mobile-first discovery. Never crop a horizontal video to vertical; re-generate or re-frame it, because letterboxed video reads as recycled and gets suppressed.
The cheat sheet
| Platform / placement | Aspect ratio | Notes |
|---|
| TikTok | 9:16 | Full-screen vertical; the default | | Instagram Reels | 9:16 | Same as TikTok | | YouTube Shorts | 9:16 | Same as TikTok | | Instagram / Facebook Stories | 9:16 | Full-screen vertical | | Instagram feed | 4:5 or 1:1 | 4:5 takes more vertical space in-feed | | Facebook feed | 1:1 or 4:5 | Square is the safe default | | YouTube (standard) | 16:9 | The one place horizontal still rules | | Product page / listing | 1:1 or 16:9 | Match your existing product imagery | | Pinterest | 9:16 or 2:3 | Tall formats dominate | | LinkedIn | 1:1 or 16:9 | Square performs well in-feed |
The single rule that matters most
Produce natively in the target ratio. Do not crop.
This is the mistake that quietly kills reach. Taking a 16:9 video and posting it to TikTok produces one of two bad outcomes: letterbox bars (which instantly signal recycled advertising content and get scrolled past), or a centre-crop that cuts the subject out of frame.
Feed algorithms reward content that looks native to the platform. A letterboxed video announces that it wasn't made for that feed, and performance follows accordingly.
Why 9:16 is the default in 2026
Mobile-first, full-screen vertical is where discovery happens. TikTok, Reels, Shorts, and Stories all use it, and between them they represent the majority of new-audience reach for most brands.
If your production budget only supports one format, make it 9:16, then derive other ratios from that source rather than the reverse — it's easier to place a vertical subject into a wider frame than to recover a subject cropped out of a horizontal one.
Producing multiple ratios without multiplying the work
The traditional obstacle is that each ratio is a separate export, and doing it well means re-framing rather than cropping. That's tedious by hand — which is why most brands post one ratio everywhere and underperform on the rest.
Generating video from product photos changes this: because the source is an image rather than a fixed-frame video, the same product can be rendered natively into 9:16, 1:1, and 16:9 without a crop-and-hope step. PixelMotion exports the formats each platform expects, so covering four placements is a settings change rather than four editing sessions.
Model choice interacts with this too. Real per-second inference costs mean producing three ratios of a 5-second clip costs about $0.45 on Kling 2.6 ($0.07/s) or $0.45 on Hailuo 2.3 Fast — versus $7.50 on Runway Gen-4.5 ($0.50/s). If you're producing multiple ratios of everything, model selection matters three times over.
Practical checklist
- Default to 9:16 unless you have a specific reason not to.
- Keep critical content centred so a safe-area crop never destroys the shot.
- Assume muted playback — never rely on audio to carry meaning.
- Check the safe areas. Platform UI (captions, buttons, profile chrome) overlays the top and bottom of vertical video; keep text out of roughly the top and bottom 15%.
- Export natively per platform rather than uploading one file everywhere.
Frequently Asked Questions
What aspect ratio is best for social media video?
9:16 vertical is the best default in 2026 — it's the native format for TikTok, Instagram Reels, YouTube Shorts, and Stories, which together drive most mobile discovery. Use 1:1 square for feed posts that must work across several platforms, and 16:9 only for standard YouTube and desktop contexts.
Can I post a horizontal video on TikTok?
You can, but it performs poorly. A 16:9 video on TikTok either shows letterbox bars — which reads as recycled ad content and gets scrolled past — or has to be centre-cropped, which often cuts the subject out of frame. Produce natively in 9:16 instead.
What is the difference between 9:16 and 4:5?
9:16 is full-screen vertical, used by TikTok, Reels, Shorts, and Stories. 4:5 is a taller-than-square format used in the Instagram and Facebook feeds, where it occupies more vertical space than 1:1 without going full-screen. They serve different placements.
Should I make separate videos for each platform?
Ideally you produce the same content in each platform's native ratio rather than one file posted everywhere. That doesn't mean shooting multiple times — generating from product photos lets you render 9:16, 1:1, and 16:9 from the same source without cropping.
Where do platform UI elements cover my video?
Vertical video is overlaid by captions, buttons, and profile chrome at the top and bottom. Keep essential content and text out of roughly the top and bottom 15% of the frame so nothing important is obscured.
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