AI Video Sizes for Every Platform: 9:16, 16:9, 1:1 and 21:9 Explained
Nothing makes content look amateur faster than a video with black bars, or a vertical post where the subject’s head is cropped off. With AI video there’s an extra reason to get this right: the model composes the shot for the ratio you choose. Pick the ratio first and the framing is built for it. Crop afterward and you throw away part of the picture you paid for.
- 9:16 for TikTok, Reels, Shorts and Stories. 16:9 for YouTube and websites.
- 1:1 works almost everywhere in feeds; 21:9 is for cinematic, letterboxed looks.
- Choose the ratio before generating. AI composes the whole shot around it.
- Keep faces and captions out of the top and bottom edges of vertical video, where app buttons sit.
Video Sizes by Platform
| Platform | Best ratio | Common resolution |
|---|---|---|
| TikTok | 9:16 | 1080×1920 |
| Instagram Reels and Stories | 9:16 | 1080×1920 |
| YouTube Shorts | 9:16 | 1080×1920 |
| YouTube (standard) | 16:9 | 1920×1080 or higher |
| Instagram and Facebook feed | 4:5 or 1:1 | 1080×1350 or 1080×1080 |
| LinkedIn feed | 1:1 or 16:9 | 1080×1080 or 1920×1080 |
| X (Twitter) | 16:9 or 1:1 | 1280×720 or 1080×1080 |
| Website hero or presentation | 16:9 or 21:9 | 1920×1080 or wider |
Platforms update their recommendations from time to time, but these have been stable for years and are safe defaults.
What Each Ratio Is Good At
9:16 vertical
Fills a phone screen completely, which is why every short-form platform uses it. Great for a single subject, faces, product close-ups and tall scenes (waterfalls, city streets, people walking toward the camera). Weak for wide landscapes and groups.
16:9 widescreen
The standard for YouTube, TVs and laptops. Best for landscapes, two people in conversation, establishing shots and anything with horizontal movement.
1:1 square
The safe all-rounder for feeds. It takes more vertical space than 16:9 in a scrolling feed, and nothing important gets cropped in previews.
21:9 cinematic
The ultra-wide movie look. Use it for trailers, dramatic openers and website banners. It will show black bars on most phones, so it’s a deliberate stylistic choice.
Choosing a Ratio in PulseMotionHub
- Text to Video and Image to Video: choose 16:9, 9:16, 1:1 or 21:9 from the aspect ratio menu before generating.
- AI Images: choose square, landscape, portrait or cinematic.
- AI Director (Studio plan): 16:9 widescreen or 9:16 for Shorts and TikTok.
Vertical Video Safe Zones
On TikTok, Reels and Shorts, the app places buttons, captions and your username over the video. As a rule of thumb, keep faces, text and products away from the bottom 20% and the top 10% of the frame, and a little away from the right edge where the like and share buttons sit. When you prompt, ask for the subject "centered in the frame" and leave headroom.
One Video, Many Platforms
If you’re posting everywhere, you have two options:
- Generate twice. Make a 9:16 version and a 16:9 version from the same prompt. At 1 credit per 5-second Kling 2.5 Turbo clip, this is often the cleanest option.
- Generate square and crop. A 1:1 clip can be cropped to 4:5 for feeds without losing much. Cropping 1:1 to 9:16 loses the sides, so keep the subject centered.
Common Mistakes
- Uploading 16:9 to TikTok, leaving a tiny strip of video in a sea of black.
- Captions placed where the app’s interface covers them.
- Cropping AI video to a new shape and cutting off the part of the scene that made it interesting.
- Exporting at low resolution. Upscale 2x (1 credit) or 4x (2 credits) before posting if a clip looks soft.
Frequently Asked Questions
What aspect ratio is best for TikTok, Reels and Shorts?
Vertical 9:16, usually exported at 1080×1920.
What aspect ratio should I use for YouTube?
16:9 widescreen for standard videos, at 1920×1080 or higher. Use 9:16 for YouTube Shorts.
Can I change the aspect ratio of an AI video after generating?
You can crop it, but you lose part of the frame. It’s better to choose the ratio before generating, because the model composes the shot for that shape.
Which aspect ratios does PulseMotionHub support?
Text to Video and Image to Video support 16:9, 9:16, 1:1 and 21:9. AI Images supports square, landscape, portrait and cinematic. AI Director supports 16:9 and 9:16.
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Create in the Right Shape From the Start
Generate video in 9:16, 16:9, 1:1 or 21:9 from 1 credit per clip. Subscribe from $47/mo or buy credits pay-per-use. New customers get 20% off their first card payment.
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