AI Video Aspect Ratio Guide: 16:9, 9:16, 1:1 and 21:9
Choose the right MiniMax H3 aspect ratio for YouTube, vertical short video, square ads, portraits, editorial video, and cinematic widescreen.
Why Aspect Ratio Matters
Aspect ratio changes the composition the model must create. A landscape prompt has room for lateral movement and environment, while a vertical prompt favors full-body subjects, height, and movement toward or away from the camera. Choose the final publishing format before generating whenever possible.
Supported Formats
16:9 landscape
Use for conventional web video, presentations, desktop playback, and wide establishing shots. Place important action away from the extreme edges if the clip may later be cropped.
9:16 vertical
Use for short-form mobile feeds. Describe vertical composition explicitly: full-body framing, tall architecture, overhead-to-ground movement, or a centered subject with space for interface overlays.
1:1 square
Useful for flexible social placements, product loops, and compositions with a strong central subject. Avoid very wide camera moves that depend on horizontal space.
4:3 and 3:4
4:3 creates a classic landscape or archival feeling. 3:4 is useful for portraits, editorial fashion, artwork, and mobile placements that need more width than 9:16.
21:9 cinematic widescreen
Useful for landscapes, vehicles, side-to-side action, and dramatic negative space. Keep key subjects large enough to remain readable on smaller screens.
Composition Tips
- Mention where the subject appears: centered, left third, foreground, or distant background.
- Match camera movement to the frame: lateral tracking suits wide formats; approach and reveal work well vertically.
- Leave safe space if captions, buttons, or logos will be added in editing.
- Generate in the target ratio instead of relying on a heavy crop later.
Quick Aspect-Ratio Decision Table
| Delivery goal | Start with | Prompt for |
|---|---|---|
| YouTube, website section, presentation | 16:9 | Horizontal movement, groups, rooms, or landscape context |
| TikTok, Reels, Shorts, mobile story | 9:16 | Full-body framing, height, and movement toward the camera |
| Flexible social ad or product loop | 1:1 | One central subject with even space around it |
| Editorial portrait or mobile feed | 3:4 | A person or tall product with more side room than 9:16 |
| Classic or archival-looking scene | 4:3 | Controlled framing with moderate horizontal space |
| Cinematic banner or panoramic action | 21:9 | Side-to-side movement and deliberate negative space |
Treat this table as a starting point, not a platform guarantee. Interfaces and placement rules change, and the same platform may crop a video differently in its feed, profile, advertisement, or embedded player. Check the current publishing preview before delivering the final version.
Choose a Ratio by Shot, Not Only by Platform
Start with the subject’s movement. Side-to-side travel, groups, rooms, and landscapes need horizontal space; a person walking toward camera, a tall product, or architecture often benefits from a vertical frame. Square and 3:4 formats are practical when the subject stays near the center and the same asset may appear in several placements.
Text-to-video lets you select the output ratio directly. Image-to-video follows the source image, so crop the opening frame before upload. Switching ratios after generation can remove hands, products, or environmental context even when the resolution remains high.
Safe Areas for Editing
Keep important faces, labels, and products away from the outer edge. Mobile platforms may cover the top, bottom, or right side with captions and controls. If you plan to add subtitles, leave calm visual space in the lower portion of the frame rather than asking the model to generate exact text.
Review the first and last frames as well as the middle of the clip. Camera movement can push a subject into an unsafe area even when the opening composition looks correct.
Frequently Asked Questions
Which ratio should I use for a website hero?
16:9 is a practical default for wide desktop sections. Keep the main subject near the center so the video can tolerate responsive cropping on narrower screens.
Can one video work for both landscape and vertical placements?
Sometimes, but a heavy crop changes composition. Generate separate versions when the subject or action depends on the full width or height of the original frame.
Does image-to-video have a ratio selector?
No. It uses the uploaded image ratio. Prepare the source first or use text-to-video when you need to choose from the supported output formats.
Choose the Frame Before You Generate
Open the MiniMax H3 generator, select the final delivery ratio, and write the subject position into the prompt before adding style details. A short test reveals framing problems more cheaply than cropping a finished long clip. For image-led work, prepare the source with the image-to-video guide before upload.
MiniMax H3 Video is an independent service and is not affiliated with or endorsed by MiniMax.
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