The Open Graph Image size (1200×630px)
The Open Graph image, set via the og:image meta tag, is what most platforms show when your web page or article is shared as a link. 1200x630 pixels at 1.91:1 is the widely supported standard that renders as a large, full-width card across Facebook, LinkedIn, Slack, and many others, rather than a small cramped thumbnail.
This single image has to work everywhere a link is pasted, and different platforms crop it slightly differently. Because of that, keep your title text, logo, and focal subject within a central safe area and avoid placing anything critical near the edges, which can be trimmed depending on where the link appears.
Legibility at reduced sizes matters because link cards often display fairly small, especially in chat apps. Use large, high-contrast text and one clear visual so the card communicates at a glance. Serving a proper 1200x630 also helps social scrapers cache a crisp preview; undersized or missing images fall back to tiny icons or no image at all, which hurts click-through.