To test an Open Graph image, inspect the page’s served <head> for an og:image URL, open that URL directly to verify the file and access controls, then use the destination platform’s inspector to see what its crawler actually fetched. For LinkedIn, verify a maximum file size of 5 MB, minimum dimensions of 1200 × 627 pixels, and the recommended 1.91:1 aspect ratio. If the preview is stale, LinkedIn says changes can take up to 48 hours; Post Inspector refreshes previews for future posts, not posts that already exist.
What an Open Graph image test must prove
A reliable test answers four separate questions:
- Does the page publish the required Open Graph metadata?
- Does
og:imagepoint to the intended, correctly sized file? - Can the social platform’s crawler retrieve that file without authentication, blocking, or a failed response?
- Has the platform refreshed its cached copy of the page?
Testing only the image in an editor is insufficient. A perfect 1200 × 627 PNG can still be absent from a preview if the crawler cannot reach its URL, while a page can expose an image that is technically reachable but not the image you meant to share.
1. Inspect the page’s Open Graph tags
The Open Graph protocol defines four required properties: og:title, og:type, og:image, and og:url (Open Graph Protocol). They should be present in the HTML served for the public URL, normally inside the document’s <head>.
View source, not just the rendered DOM
- Open the exact URL you intend to share.
- Use your browser’s “View page source” command, or request the URL with an HTTP client.
- Search for
property="og:image"and inspect itscontentvalue.
A minimal set looks like this:
<meta property="og:title" content="Example article">
<meta property="og:type" content="article">
<meta property="og:image" content="https://example.com/images/share-card.jpg">
<meta property="og:url" content="https://example.com/article">Confirm that there is one intentional image tag, that the URL is absolute and uses HTTPS, and that the og:url is the canonical page URL. JavaScript that inserts tags after the initial response may not be processed the same way by every crawler, so server-rendered metadata is the safer implementation.
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The protocol also supports structured image properties. Add og:image:secure_url when you provide an HTTPS equivalent, og:image:type for the MIME type, og:image:width and og:image:height for dimensions, and og:image:alt for descriptive alternative text. These values should describe the same file named by og:image; they do not repair an inaccessible or incorrect URL.
2. Test the image URL itself
Copy the exact value of og:image into a new browser tab. It should return the intended image without a login screen, cookie wall, expiring token, or HTML error page.
Verify the response
- Use HTTPS and a publicly routable hostname.
- Return a successful HTTP response, normally
200 OK. - Send an accurate image
Content-Type, such asimage/jpeg,image/png, orimage/webp. - Do not require cookies, Basic Authentication, a session, or a browser-only challenge.
- Ensure redirects end at the intended image and do not loop.
You can inspect headers with:
curl -I -L "https://example.com/images/share-card.jpg"A successful browser view does not guarantee crawler access. Firewalls, robots or bot rules, geographic restrictions, signed URLs that expire, and protected directories can block a platform even when the file works for you. LinkedIn specifically warns that blocked retrieval or a protected image location can prevent an otherwise valid image from appearing (LinkedIn Help).
Confirm the bytes are an image
Download the response and check it with an image tool or your operating system’s file information. If the file starts with an HTML error document, a redirect page, or a placeholder, the metadata is pointing at the wrong resource. Also check the actual pixel dimensions rather than trusting a filename or optional metadata tag.
3. Compare the file with LinkedIn’s specifications
LinkedIn’s sharing-module guidance is platform-specific, not a universal Open Graph rule. The published limits are:
| Check | LinkedIn sharing-module guidance | What to do |
|---|---|---|
| Minimum dimensions | 1200 × 627 pixels | Export at least this size. |
| Recommended ratio | 1.91:1 | Use 1200 × 627 or an equivalent ratio to avoid cropping. |
| Maximum file size | 5 MB | Compress or resize files above the limit. |
These are LinkedIn specifications. Other destinations may use different dimensions, ratios, limits, or metadata rules; do not treat the LinkedIn values as guarantees for every network.
Look for practical image failures
- Wrong crop: important text or a logo sits outside the central safe area.
- Oversized file: high-resolution PNGs can exceed 5 MB even when their dimensions are suitable.
- Unexpected format: a server may label a file as an image while returning unsupported or corrupted bytes.
- Variant mismatch: a CDN transformation or responsive image rule serves a different file than the one you reviewed.
4. Use LinkedIn Post Inspector to test the fetched preview
After checking your HTML and image endpoint, submit the page URL to LinkedIn Post Inspector. Review the resulting title, description, canonical URL, and image. This is the closest practical check of what LinkedIn’s crawler has retrieved.
- Open Post Inspector and enter the complete page URL.
- Run the inspection.
- Confirm that the displayed image is the intended artwork and that the text belongs to the current page.
- If the result is wrong, fix the source metadata or image endpoint, then inspect again after the platform allows a refresh.
If the inspector reports no image, return to the URL-access test: a blocked request, protected directory, authentication requirement, or failed redirect is more likely than a design problem.
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5. Handle stale previews and cache timing
Social platforms cache fetched metadata and images. LinkedIn’s troubleshooting guidance says to allow up to 48 hours after a URL was shared or its tags were updated (LinkedIn Help). Post Inspector can refresh the preview used for new posts, but an existing post keeps the preview it already stored.
A safe refresh sequence
- Publish the corrected tags and image at the production URL.
- Open the image URL directly and verify the new bytes.
- Run Post Inspector for the page.
- Wait for propagation if LinkedIn still shows the old result.
- Create a new test post only after the inspector displays the corrected preview.
Changing the image filename or adding a query string can help you distinguish a new resource during debugging, but it does not remove the need to correct the original metadata and access rules.
6. A repeatable developer checklist
- Fetch the production HTML, not a local development page.
- Find exactly one intended
og:imagevalue. - Check
og:title,og:type, andog:url. - Resolve relative paths and confirm the final HTTPS URL.
- Request the image without browser cookies or credentials.
- Verify status, redirects, MIME type, bytes, dimensions, and file size.
- Check firewall, WAF, hotlink, robots, and directory-protection rules.
- Inspect the URL in LinkedIn Post Inspector.
- Record when tags changed and allow the documented cache window.
Common errors and fixes
The page has no og:image
Add the tag to the server-rendered head through your CMS theme or template. Confirm that the final response—not only an editor preview—contains it.
The inspector shows an old image
Verify the production response, then allow LinkedIn’s stated 48-hour window. Post Inspector affects future posts; it cannot rewrite an existing post’s stored preview.
The image opens for me but not for LinkedIn
Remove authentication and expiring access requirements, permit crawler requests through the firewall, and test from a neutral network. LinkedIn identifies blocked retrieval and protected locations as causes.
The image is cropped or rejected
Measure the actual file, keep it at least 1200 × 627 pixels, target 1.91:1, and keep the file at or below 5 MB for LinkedIn.
The wrong page image appears
Look for duplicate Open Graph tags, template defaults, a stale CDN object, or a redirect to another canonical URL. Keep one deliberate image declaration and purge the cache serving the old HTML or asset.
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FAQ
Do Open Graph tags have to be in the head?
They belong in the page metadata head, where crawlers can read them in the initial HTML response. Server-rendering is the dependable approach.
Can Post Inspector change an existing LinkedIn post?
No. It refreshes the preview used for future posts; an existing post retains its previously cached preview.
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Are LinkedIn’s dimensions universal?
No. The 1200 × 627 minimum, 1.91:1 recommendation, and 5 MB maximum are LinkedIn sharing-module guidance.
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