Twitter card validator: see your X card before you post

What X (Twitter) needs

twitter:card decides the card: summary_large_image for the wide image card, summary for a small square thumbnail. Without it, X shows no image card.
X falls back to og:title, og:description and og:image when the twitter:* versions are missing, so one set of Open Graph tags plus twitter:card is enough.
Large image card: a 2:1 ratio, at least 300×157 and at most 4096×4096 pixels, under 5 MB, as JPG, PNG, WebP, GIF (a GIF shows its first frame).
Summary card: a 1:1 image of at least 144×144, cropped to a square.
X fetches the page with its Twitterbot crawler, which respects robots.txt.

	Minimum	Aspect ratio	Max file size	Formats
X (summary_large_image)	300×157	2:1	5 MB	JPG, PNG, WebP, GIF
X (summary)	144×144	1:1	5 MB	JPG, PNG, WebP, GIF

Values from the platform's own documentation, checked 2026-11-02 (all platforms: OG image size). Sources: · X Developer Platform: Summary card with large image (archived 2026-01-12) · X Developer Platform: Cards markup (archived 2026-01-16) · X Developer Platform: Summary card (archived 2025-12-16)

Tags X (Twitter) reads

X (Twitter) link preview not showing or not updating?

No image? Check that twitter:card is there and says summary_large_image — the most common cause of a small or missing card.
Make sure robots.txt does not disallow Twitterbot and your firewall or bot protection does not challenge it.
Use an absolute https:// URL for the image and keep it under 5 MB and within 4096×4096.
X documents no refresh tool and caches cards. After a fix, share the URL with a query string (?v=2) or give the image a new file name, so X fetches it fresh.
Print the tags in the server HTML: Twitterbot does not run JavaScript.

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Questions

Does the X (Twitter) Card Validator still work?

X's Card Validator stopped showing previews; the post composer is the only place X itself shows one, and only after you paste the link. This page shows the card from your tags without posting anything.

What image size does a Twitter card need?

For summary_large_image X documents a 2:1 ratio, at least 300×157, at most 4096×4096 pixels and under 5 MB. 1200×630 or 1200×600 both work.

Why does my link show a small thumbnail instead of a big image?

twitter:card is missing or set to summary. Set <meta name="twitter:card" content="summary_large_image">.

How do I refresh an old Twitter card?

X publishes no way to clear its card cache. Change the URL you share (a query string works) or the image's URL, and X will fetch the page again.