Google Discover Image Requirements: The 1200px Rule, max-image-preview, and How to Keep Those Big Images Fast

Google Discover shows your article as a large card only when the image is at least 1200 pixels wide and the page allows large previews through the max-image-preview:large robots setting (or uses AMP). Miss either condition and you get a small thumbnail, or often no Discover traffic worth mentioning. Google's own documentation also says not to use your site logo as the image.

This matters more heading into Q4. Discover is a feed, not a search results page. People don't type anything, they scroll, and the image is the first thing they judge. Google has said large images in Discover lifted click-through by 5%, time on page by 3% and user satisfaction by 3% compared with small thumbnails. On a feed that can send more traffic than search to news and lifestyle publishers, those are meaningful numbers.

Step 1: Check the Robots Setting Before You Touch Any Image

Start here, because it's the most common silent failure. If your pages don't allow large image previews, Discover won't show large cards no matter how good your images are.

Open any article, view the source and search for max-image-preview. You want to see:

<meta name="robots" content="max-image-preview:large">

It can also be sent as an X-Robots-Tag: max-image-preview:large HTTP header. Yoast, Rank Math and most modern SEO plugins add it by default, but a custom theme, a headless setup or an old robots tag written years ago may not. If you see max-image-preview:standard or none, that is your Discover problem.

Step 2: Make the Main Image at Least 1200px Wide

The width rule is a hard minimum, not a target to beat. A 1200px-wide image qualifies, and a 4000px one gains nothing more.

For the three aspect ratios Google asks for in Article structured data, these sizes work well:

Ratio	Size	Where it's used
16:9	1200x675	Discover cards, most article layouts
4:3	1200x900	Some card layouts, Top Stories
1:1	1200x1200	Square placements

Google's structured data guidelines ask for images of at least 50,000 pixels in total (width multiplied by height). All three sizes above are far past that. List all three in the image array of your Article JSON-LD and let Google choose the crop it needs, instead of letting it crop a single image badly.

Step 3: Choose an Image That Earns the Tap

Discover's guidance is to use "compelling, high-quality images". In practice that means:

• Not your logo. Google names this explicitly. A logo tells the reader who wrote the article, not what it's about.
• A real subject, readable at phone size. The card is about 360 pixels wide on most phones. Detailed infographics and tiny text turn to mush at that size.
• No text baked into the image. The headline sits right under it already. Repeating it on the image wastes the space and looks like an ad.
• Center-weighted composition. Discover and social platforms crop differently. Keep the subject in the middle 60% of the frame so no crop cuts it off.
• Honest. An image that promises something the article doesn't deliver may get the click, but that kind of clickbait is what Discover's quality systems are designed to demote over time.

Step 4: Keep the File Small, Because Big Pixels Don't Mean Big Files

This is where many publishers get it wrong. They read "large images" and upload the photographer's 5 MB original. Discover measures pixel dimensions, not bytes, and the same image is almost always your page's Largest Contentful Paint element. A heavy hero image costs you on Core Web Vitals.

The workflow:

1. Resize the original to exactly 1200px wide for each ratio you need.
2. Convert to WebP at quality 78 to 82. For a detailed photo you'll usually land between 100 and 200 KB.
3. Compress any JPEG fallbacks to under 300 KB.
4. Serve the hero with fetchpriority="high" and never lazy-load it. It needs to appear immediately.

Step 5: Match og:image to Your Main Image

Discover can use your Open Graph image as well as structured data, and social platforms rely on it entirely. If og:image points to a 600px thumbnail or your logo while the article's hero is a sharp 1200px photo, you're sending mixed signals. Point og:image at the 1200x675 version (1200x630 is the common social standard and also clears the width bar) so every platform gets the same large, relevant image.

A Quick Audit You Can Run Today

Pick your ten highest-traffic articles and check:

• Does the page source include max-image-preview:large?
• Is the main image at least 1200px wide in the HTML, not just in your media library?
• Does the Article JSON-LD list three aspect ratios?
• Is the hero image under 250 KB?
• Is og:image the same image at 1200px or wider?

Most sites fail at least one of these on half their pages. Each fix is small, and they add up to the difference between a thumbnail and a large card, repeated across every story you publish.

Related reading:

• Why Your LCP Is Failing and How to Fix It: the page-speed side of large hero images
• AVIF vs WebP vs JPEG: 2026 Benchmark: picking the format for your hero images
• Google INP and Core Web Vitals for Images: how images affect responsiveness scores