Google Uses Both schema.org Markup and Og:image Meta Tag for Thumbnails in Google Search and Discover

Why It Matters

Thumbnail images drive click‑through rates, so controlling which image Google displays directly impacts traffic and brand visibility in Search and Discover.

Key Takeaways

• Google uses schema.org and og:image for thumbnail selection
• Use primaryImageOfPage or mainEntity markup to specify image
• Provide high‑resolution 1200 px wide images, 16:9 aspect
• Avoid logos or text‑heavy images in markup
• Enable large preview via max-image-preview:large or AMP

Pulse Analysis

Google’s clarification that schema.org markup and the og:image tag both feed its thumbnail algorithm gives webmasters a clearer path to influence visual SERP outcomes. By explicitly supporting properties like primaryImageOfPage and mainEntity, Google encourages structured data adoption, which not only aids image selection but also enriches overall page understanding. This dual‑source approach reduces reliance on heuristic image picking, allowing publishers to align the most relevant visual asset with their content’s intent.

For Discover, the stakes are higher because large, compelling images can be the sole driver of clicks. Google now recommends images at least 1200 pixels wide, 16:9 aspect ratio, and a minimum file size of 300 KB to ensure high quality across devices. The platform automatically crops images, but providing a well‑composed visual in the og:image tag helps preserve key elements after cropping. Enabling the max-image-preview:large directive or serving content via AMP further signals readiness for large previews, increasing the likelihood of selection.

Practically, marketers should audit existing pages for generic logos or text‑laden graphics in both schema.org fields and og:image tags, replacing them with context‑relevant, high‑resolution photos. Consistency across markup types prevents conflicting signals that could confuse Google’s selection engine. By adhering to these updated guidelines, sites can boost click‑through rates, improve user engagement, and ultimately capture more organic traffic from both Search and Discover ecosystems.