Basics · 4 min
AI Video Aspect Ratios: Choosing 16:9, 9:16, or 1:1
Picking the right AI video aspect ratio is a small choice that has a big effect on how your clip lands. The shape of the frame decides how it fits each platform, how much of your subject is visible, and whether viewers see black bars or a full, edge-to-edge image. SDMini lets you set the ratio before you generate, so you start with the correct frame instead of cropping later.
There are three you will use most: 16:9 landscape, 9:16 vertical, and 1:1 square. Each one has a clear home. This guide explains where each fits and how to choose without second-guessing.
16:9 landscape: the wide standard
16:9 is the classic widescreen shape. It is the right choice for YouTube videos, website headers and embeds, presentations, and anything watched on a TV or laptop. It gives the camera room to show environment and movement, which suits cinematic and B-roll clips.
Use 16:9 when the setting matters as much as the subject, for example a landscape, a product in a scene, or a sweeping camera move. Posting a 16:9 clip to a vertical-first feed will leave bars, so reserve it for horizontal destinations.
9:16 vertical: built for phones
9:16 is the tall format that fills a phone screen. It is what TikTok, Instagram Reels, and YouTube Shorts expect, and it is how most people watch casually. A vertical clip feels native in those feeds and keeps the subject large and close.
Generate in 9:16 from the start rather than cropping a wide clip down, which loses the sides of your composition. When you write the prompt, frame for a tall shot: a single subject centered, with vertical motion like a push-in reading especially well.
1:1 square: the flexible middle
1:1 square sits between the two. It performs well in social feeds where a square takes up more vertical space than a landscape clip but is less aggressive than full vertical. It is a safe, balanced choice when a post might appear in mixed placements.
Square framing keeps the subject centered and tight, so it suits portraits, products, and single-focus motion. If you are unsure where a clip will end up, 1:1 travels reasonably well across platforms.
A quick way to decide
Ask one question: where will this play? YouTube, a website, or a screen means 16:9. TikTok, Reels, or Shorts means 9:16. A mixed feed or a single-subject post means 1:1. Decide before generating so the model composes for that shape.
If you genuinely need the same idea in two shapes, generate it twice at the two ratios rather than cropping one into the other. Each render then uses the full frame for its format, which always looks cleaner than a crop.
Frequently asked questions
- Which aspect ratio is best for TikTok and Reels?
- 9:16 vertical. It fills the phone screen and looks native in short-form feeds like TikTok, Instagram Reels, and YouTube Shorts.
- What ratio should I use for YouTube?
- 16:9 for standard YouTube videos and embeds. For YouTube Shorts, use 9:16 vertical instead.
- Can I change the aspect ratio after generating?
- You set it before generating so the model composes for that shape. For another ratio, it is better to generate again than to crop, which loses part of the frame.
- What ratios does SDMini support?
- 16:9 landscape, 9:16 vertical, and 1:1 square, so you can match every major platform.