An OG image is the picture that shows up when someone pastes a link to your page into Facebook, LinkedIn, Slack, WhatsApp, iMessage and similar apps. You choose it with a single line in the page's code. Without one, the app either guesses an image from the page or shows a plain text link.
How a link preview picks its picture
"OG" stands for Open Graph, the set of meta tags that describe a page to sharing platforms. The image is declared in the page head like this: meta property="og:image" content="https://example.com/share.jpg". When a link is shared, the platform's crawler downloads the page, reads that tag, fetches the image and stores a copy to use in the card.
Related tags help the platform display it properly: og:image:width and og:image:height give the size up front, and og:image:alt describes it. X (formerly Twitter) reads its own twitter:image tag first but falls back to og:image.
Sizing an OG image that works everywhere
The widely used size is 1200 by 630 pixels, a ratio of about 1.91 to 1, which is what Facebook recommends for link shares. Platforms crop differently, and some messaging apps show a square thumbnail, so keep text and logos away from the edges. Use an absolute URL starting with https, and a JPEG or PNG; support for WebP in previews is not consistent across every app.
Example: a gym's class page
A gym shares its new spin class page in a local Facebook group. With no og:image, Facebook picks the first image it finds, which turns out to be a tiny payment icon from the footer. After the owner adds a 1200 by 630 photo of the studio with the class name in large type, the shared link shows a full-width, readable card, and the next post looks deliberate.
Who sees your OG image
If your pages ever get shared, in group chats, newsletters, or on social media, the OG image is often the first thing people see of your business. It does not affect Google rankings directly. It is worth setting a sensible default for the whole site and a specific image for key pages such as the homepage, offers and blog posts.
OG image mistakes
- Using a relative path.
/share.jpgoften fails; crawlers need the full address. - Blocking the crawler. If the image sits behind a login or is disallowed in robots.txt, previews come up blank.
- Expecting an instant update. Platforms cache previews. Facebook's Sharing Debugger and LinkedIn's Post Inspector let you force a fresh scrape.
- Tiny text. Cards are often shown small on phones, so a few large words beat a paragraph.
Related terms
- Open Graph: the full protocol the image tag belongs to.
- Title tag: the fallback headline when og:title is missing.
- Meta description: often reused as the card's summary text.
- JPEG: a safe format for share images.