Sizes
Cards render at 1200×630 by default, the shape every link unfurler expects. size renders the same template at another platform's shape instead, so one design can serve link previews, feed posts and stories.
| size | Pixels | Where it's used |
|---|---|---|
| og | 1200×630 | Links on X, LinkedIn, Facebook, Slack and Discord. The default. |
| square | 1200×1200 | Instagram and LinkedIn feed posts. |
| story | 1080×1920 | Instagram and Facebook stories, TikTok, Reels covers. |
| youtube | 1280×720 | YouTube thumbnails and 16:9 video covers. |
| wide | 1600×900 | Blog headers, email banners, presentation covers. |
https://ogsmith.app/api/og?key=og_yourkey&size=square&title=Also%20on%20Instagram
Built-in templates are laid out once and scaled to whichever canvas you ask for, so type and spacing keep their proportions and the shorter shapes don't simply leave gaps. Templates that anchor copy to one edge gather it into the middle on the taller canvases.
Your own templates work differently: their layers hold absolute coordinates, so the canvas is part of the design and you choose it in the editor. Passing size alongside tpl has no effect; the design's own canvas applies.
Changing size changes the image, so bump your cache version if you are switching an already-published card to a new shape.