Question 1

What size should an OG image be?

Accepted Answer

Use 1200x630 pixels, a 1.91:1 ratio, saved as a PNG or JPG under 5 MB. Facebook recommends at least 1200x630 for sharp previews and takes files up to 8 MB; LinkedIn asks for at least 1200x627 at 1.91:1 and up to 5 MB. Below 600x315, Facebook shows the image much smaller. The checker measures your image from the file itself.

Question 2

Why is my OG image not showing on LinkedIn, X or Slack?

Accepted Answer

Usually the og:image tag is missing; the image address is relative, uses http or sits behind a login; the file is too small or too heavy; the tags are added by JavaScript after the page loads (X and Apple say their crawlers do not run JavaScript); or the app still keeps an old copy. X needs a twitter:card tag or Open Graph tags to fall back on, LinkedIn shows images under 401 pixels wide as a small thumbnail, and Slack does not expand a link again that was shared in the same conversation within the past hour. Check the page here: apart from cached copies and that Slack rule, each of these shows up with its fix.

Question 3

How do I clear a cached link preview?

Accepted Answer

Apps keep a copy of each link's preview for a while. For Facebook, paste the link into Meta's Sharing Debugger and have it scrape the page again; otherwise Facebook updates link details every 30 days. For LinkedIn, use LinkedIn's Post Inspector; the new preview applies to new posts only. X keeps card data for up to 7 days and suggests checking a preview by pasting the link into the post composer without posting. Slack caches a link for around 30 minutes. If the image itself changed, give it a new address, or Facebook will not update it.

Question 4

What does twitter:card do?

Accepted Answer

It tells X which card to show for your link. summary_large_image shows the image large, across the width of the post; summary shows only a small square thumbnail. X uses your Open Graph tags for the title, description and image when its own tags are missing, so most pages only need twitter:card on top.

Question 5

What does og:image:alt do?

Accepted Answer

It describes what is in the image for people who cannot see it. The Open Graph protocol defines it as a description of the image, not a caption, and asks for it on every page that sets og:image. The checker reads og:image:alt and its X twin, twitter:image:alt, and flags a share image without either.

Question 6

Is the OG image checker free?

Accepted Answer

Yes. Checking a page is free and needs no account, and only public pages can be checked. Making a new image in OG Image Lab is free too; downloading the PNG, copying the meta tags or using the image on the UX Pilot canvas needs a free UX Pilot account.

OG image checker

Open Graph checker and link preview test

What the checker looks at

FAQ