Image Sitemaps in 2026: What They Do, When You Need One, and How to Add It

By the ImageSEO Team · updated October 2026 · about 7 min read

Quick answer: an image sitemap is a list of the image URLs on each page of your site, added to an XML sitemap with <image:image> tags. It helps Google find images it might otherwise miss, such as images loaded by JavaScript. It does not help them rank. If your images are normal <img> tags in the HTML, Google usually finds them anyway. On WordPress you rarely need to build one yourself: Yoast SEO and Rank Math add image entries to their sitemaps automatically. What matters more is that your sitemap actually updates, which we learned the hard way with this very article.

What an image sitemap looks like

An image sitemap isn’t a special file type. It’s a normal XML sitemap with extra tags for the images on each page:

<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
        xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">
  <url>
    <loc>https://example.com/blue-ceramic-vase/</loc>
    <image:image>
      <image:loc>https://example.com/images/blue-ceramic-vase-front.jpg</image:loc>
    </image:image>
    <image:image>
      <image:loc>https://example.com/images/blue-ceramic-vase-side.jpg</image:loc>
    </image:image>
  </url>
</urlset>

The rules, from Google’s image sitemap documentation:

• Only two tags still count: <image:image> and <image:loc>. Google removed image:caption, image:title, image:geo_location and image:license from its documentation in 2022, so there’s no point filling them in.
• Up to 1,000 images per page entry.
• Separate file or the same file. You can add image tags to your existing sitemap or keep a separate image sitemap. Google says either is fine.
• Images on a CDN are allowed, even on another domain, as long as both domains are verified in Search Console and robots.txt doesn’t block the images.

When an image sitemap actually helps

Google says image sitemaps help it discover images it might not otherwise find. In practice that means:

• Images loaded by JavaScript, for example sliders, galleries or lightboxes that insert images after the page loads.
• Images on a CDN or another host. In our 2026 crawl of the homepages of the 10,000 most-visited websites, 32.5% of images were served from a different host than the page.
• Large or fast-growing sites, such as stores adding hundreds of product photos a week, where you want new images found quickly.
• New pages that nothing links to yet. The sitemap is often the first place Google learns a page exists. More on that below.

When you don’t need to worry about it

• Your images are standard <img> elements in the page HTML. Google says standard image elements help crawlers find and process images, including images inside a <picture> element.
• Your site is small and every page is linked from your navigation or other pages.
• Your SEO plugin already adds image entries (check below).

One thing a sitemap can’t fix: CSS background images. Google says it doesn’t index CSS images. If a product photo or hero image is set with background-image, listing it in a sitemap won’t make it show up in Google Images. Use a real <img> element with alt text instead.

What happened when our own sitemap stopped updating

This article was published on 3 September 2026, and at first Google didn’t know it existed.

Our blog sitemap had been frozen since 27 August. It still returned a normal page, so nothing looked broken, but anything published after that date was missing from it. The cause turned out to be a cache: our SEO plugin cleared its cached sitemap with a database query that does nothing on servers running a persistent object cache (Redis), so the old version was kept.

The result, measured in Google Search Console:

• This article: “URL is unknown to Google”, no crawl, 0 impressions, even though dozens of other pages on the site linked to it.
• Our Google Lens article, published a week earlier while the sitemap was still updating: indexed, with 63 impressions by then.

Same template, same blog, one week apart. The difference was the sitemap. Once we fixed the cache, the sitemap updated within minutes and we asked Google to crawl the article. The lesson isn’t really about image tags: check that your sitemap actually changes when you publish. If it doesn’t, your images and pages are both invisible, however well they’re optimised.

How to add an image sitemap in WordPress

Yoast SEO

Yoast’s XML sitemaps include the images on each post and page automatically. Since Yoast SEO 18.8 they contain only the image:loc tag, matching Google’s current rules. If a theme or page builder outputs images Yoast can’t see, developers can add them with the wpseo_sitemap_urlimages filter.

Rank Math

Rank Math adds images to its post and page sitemaps when the Include Images option is on in its sitemap settings. Our own blog sitemap is generated this way: 133 of its 147 posts carry image entries.

Other options

Dedicated sitemap plugins and online generators can create a standalone image sitemap. Only use one if your SEO plugin doesn’t already add images, otherwise you’ll list the same images twice.

How to check your image sitemap

1. Open your sitemap index, usually /sitemap_index.xml (Yoast and Rank Math), and click a post or page sitemap.
2. Look for <image:loc> entries inside the URLs. View the page source if your browser shows a styled table.
3. Publish a test post and reload the sitemap. The new URL should appear within minutes. If it doesn’t, clear your caching plugin and check again; if it still doesn’t, your sitemap cache is stuck.
4. In Google Search Console, open Sitemaps, submit the sitemap index and check the date Google last read it.
5. Use URL Inspection on a new page. “URL is unknown to Google” a week after publishing is the warning sign we saw.

To audit the whole sitemap rather than one page (deleted URLs still listed, wrong lastmod dates, pages missing from it), we recommend SitemapFixer.

Image sitemaps vs what actually ranks images

A sitemap gets an image discovered. Whether it then shows up for a search depends on what Google can read about it: alt text (which Google calls the most important attribute for image metadata), the text around the image and, to a lesser degree, the file name. In our crawl of 306,634 images on the most-visited homepages, 11.3% had no alt attribute at all, so a sitemap would have sent Google to images it couldn’t describe. The image SEO guide covers the full list, and the ImageSEO plugin writes alt text and file names for a WordPress media library automatically.

Frequently Asked Questions

Do I need a separate image sitemap?

No. Adding image tags to your existing sitemap works just as well, and that’s what Yoast and Rank Math do. A separate file is only useful if you generate it with a different tool.

Does an image sitemap improve rankings?

Not directly. It helps Google find images. Ranking depends on alt text, page content and how useful the page is.

Should I still add image:caption and image:title?

No. Google removed those tags from its documentation in 2022, and Yoast stopped outputting them the same year.

How many images can one sitemap entry list?

Up to 1,000 images per page URL.

Can I include images hosted on a CDN?

Yes, including images on another domain, as long as both domains are verified in Search Console and the images aren’t blocked by robots.txt.

Will a sitemap get CSS background images indexed?

No. Google doesn’t index CSS images. Use an <img> element for any image you want in search.