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Image Optimization

Open Graph Image Sizes for Shareable Links

Ensure your links look great when shared on iMessage, Slack, Twitter, and Facebook.

Evan Kim
Published: January 2, 2026

Key Takeaways

Ensure your links look great when shared on iMessage, Slack, Twitter, and Facebook.

Every time someone shares a link — in a Slack channel, on Twitter, in an iMessage thread, on Facebook — a preview card is generated. That preview card includes a title, a description, and an image. The image comes from your website's Open Graph metadata. If you don't define it, the platform guesses — often pulling the wrong image, a tiny icon, or nothing at all.

A well-configured og:image can mean the difference between a link that gets clicked and one that gets ignored. In a Slack channel where links compete for attention, a professional, well-designed link preview immediately signals credibility. In email newsletters, a missing image makes your link look broken. Configuring Open Graph images is one of the highest-ROI technical SEO tasks you can do.

The Universal Open Graph Image Specification

  • Recommended dimensions: 1200 × 630 px
  • Aspect ratio: 1.91:1 (approximately 2:1)
  • Minimum size: 200 × 200 px (to show as a small thumbnail)
  • Recommended file size: under 300 KB
  • Format: JPG or PNG (JPG preferred for smaller file size)

The 1200 × 630 px specification is the single most universal format for link previews. It displays well on Facebook, Twitter/X, LinkedIn, Slack, Discord, iMessage (on iPhone), WhatsApp, and most email clients. This is the format you should use for every page of your website that might be shared.

Platform-by-Platform Variations

While 1200 × 630 px works everywhere, individual platforms have their own ideal display sizes:

  • Facebook: 1200 × 628 px. Displays at 600 × 315 px on desktop feeds. Square (1:1) images are also used for smaller card formats.
  • Twitter/X: Large Image Card: 1200 × 628 px. Small Image Card (meta tag: summary): 120 × 120 px square.
  • LinkedIn: 1200 × 628 px for shared links.
  • Discord: Displays og:image at a maximum of 400 × 210 px. High resolution images are scaled down but maintain crispness.
  • Slack: Displays up to 360 × 190 px. Make sure your main visual element is readable at this size.

How to Set Your Open Graph Image

Open Graph images are defined via HTML meta tags in the <head> of your page:

<meta property="og:image" content="https://yourdomain.com/images/og-image.jpg" />
<meta property="og:image:width" content="1200" />
<meta property="og:image:height" content="630" />

The URL must be absolute (starting with https://) and publicly accessible — not behind authentication or on localhost. Crawlers fetching your og:image cannot access private URLs.

For Twitter-specific cards, also add:

<meta name="twitter:card" content="summary_large_image" />
<meta name="twitter:image" content="https://yourdomain.com/images/og-image.jpg" />

Designing an Effective og:image

Your og:image is not just a technical requirement — it's a marketing asset. Best practices:

  • Include your brand name or logo in a consistent position (bottom-left or top-left works well)
  • Include the page title or a headline — make it readable at small sizes (Slack displays at ~360 px wide)
  • Use a consistent template for all your pages — brand recognition is built through repetition
  • Avoid images that are mostly white — on platforms with light backgrounds, an all-white og:image is nearly invisible
  • Test centering — some platforms crop og:images to square. Keep important elements away from the left and right edges

Testing Your Open Graph Images

Before publishing, validate your og:image with these free tools:

  • Facebook Sharing Debugger: developers.facebook.com/tools/debug — also clears Facebook's cache of your old og:image
  • Twitter/X Card Validator: cards-dev.twitter.com/validator
  • LinkedIn Post Inspector: linkedin.com/post-inspector
  • OpenGraph.xyz: shows a preview of how your link will appear across multiple platforms at once

Summary Checklist

  • Dimensions: 1200 × 630 px
  • Format: JPG under 300 KB for best performance
  • Include og:image, og:image:width, and og:image:height tags
  • Add Twitter-specific card tags for Twitter/X
  • Validate with Facebook Debugger and Twitter Card Validator
  • Design for readability at small sizes (Slack, Discord)

Frequently Asked Questions

#open-graph#seo#sharing
EK

About Evan Kim

Digital content strategist and visual communication specialist based in South Korea. Focused on practical, precise solutions for creators.

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