Image SEO: The Complete Checklist Beyond Alt Text

You've done the alt text work. Every product photo has a real description instead of "IMG_4021," and you still can't answer the question that actually keeps you up at night: why isn't this thing showing up in Google Images? That gap is the part of image seo nobody walks you through properly. Alt text is one line item on a longer list, not the whole exam, and most of the advice you've read treats it like the only thing that matters.

I've run this exact triage for clients dozens of times: a product catalogue with clean alt text and zero visibility in Google Images, or a blog with beautifully named files that still don't rank a single photo. The cause is almost never alt text once you've already written it properly. It's somewhere else on this checklist. This is that checklist, in the order I actually work through it with a client, from "can Google see this image at all" down to "does file weight matter."

The Image SEO Checklist: What Actually Affects Google Images

How do images get into Google Images in the first place?

Before you touch a file name or write a caption, answer this one question: is the image discoverable at all? Google Images only picks up pictures placed through actual HTML image elements, meaning the <img> element, the <picture> element, or the srcset attribute, exactly as the HTML Living Standard defines them. Source: WHATWG, HTML Living Standard, the img element.

If your hero banner or category thumbnail is set as a CSS background-image, Google's own guidance for image SEO is explicit that it won't be indexed for image search at all, no matter how good the alt attribute on a nearby element looks. That's a real, checkable cause of missing images, and I've found it more often than any other issue on this list.

How do you test this yourself? Right-click the image in your browser and choose "Inspect." If the picture sits inside a style attribute or a linked stylesheet as background-image: url(...), Google Images will never see it as a discrete image resource. Swap it for an <img> tag (or a <picture> element if you need format fallbacks) and the image becomes eligible for indexing again.

Second on this check: is the page itself indexable? An image can only be found the way Google finds anything else, by crawling a page that links to it. If the page carries a noindex directive, or robots.txt is blocking the image file or its folder, the picture is invisible to Google regardless of how well it's named or described. Run your page through imagecheck.tools and it will flag missing or broken alt text and file issues across the images it can reach, but the noindex and robots.txt checks belong upstream of that: confirm the page itself is indexable before you spend a weekend renaming files that Google was never going to see.

SEO image name: fact versus folklore

This is where most "image seo" advice either overstates its case or dodges the question entirely, and it's exactly the confusion I see repeated on forums like the Shopify community, where merchants ask some version of "filenames used to matter, do they still?" The honest answer sits between the two extremes people usually land on.

Google's own guidance says filenames give Google "very light clues about the subject matter of the image." Their example is straightforward: my-new-black-kitten.jpg beats IMG00023.JPG, because the descriptive version tells a crawler something the numeric one never could.

But notice the wording. Light clues. Not a ranking factor, not something to chase, not worth stuffing keywords into. Source: Google Search Central, Image SEO best practices.

So what should you actually do with image names and seo in mind? Keep it simple:

• Use a short, descriptive phrase that matches what's genuinely in the image, not what you wish it ranked for.
• Separate words with hyphens, not underscores or spaces (search engines parse hyphens as word breaks more reliably).
• Skip keyword stuffing. blue-suede-sneakers-mens.jpg is fine. buy-cheap-blue-suede-sneakers-mens-shoes-sale-nike-adidas.jpg reads as spam and helps nothing.
• Don't burn a weekend renaming an entire back catalogue for this alone. It's a light signal sitting alongside dozens of others, and I'd rank it well below the discovery check above on your priority list.

If you're weighing whether to rename 400 product photos purely for seo image name reasons, my honest answer as someone who has watched this play out on real sites: do it opportunistically when you're touching the files for another reason (a redesign, a new upload batch), not as a standalone project chasing a light signal.

Where alt text fits into this checklist

I'm not re-teaching alt text writing here on purpose. It matters, genuinely, both for accessibility and for giving Google textual context about an image's content, and it belongs in a serious image seo checklist. But it's a big enough topic that it deserves its own space rather than three paragraphs squeezed between file names and sitemaps.

If you haven't already, our alt text guide walks through what to write for product photos, charts, icons, decorative images, and images sitting inside links and buttons. Come back here once that piece is handled.

Do images need to be in a sitemap?

No, and this trips people up because sitemaps feel mandatory once you've heard of them. Google states plainly that you can use an image sitemap to "provide the URL of images we might not have otherwise discovered." Note the framing: it's a discovery aid for images Google might otherwise miss, not a requirement for images it can already crawl through a normal <img> tag on an indexable page. Source: Google Search Central, Image sitemaps.

Where a sitemap earns its keep is the specific case Google calls out: images loaded via JavaScript. If your product gallery swaps images in after page load through a script, a crawler that doesn't execute that JavaScript (or executes it on a delayed second pass) can miss the picture entirely. Listing the image URL directly in a sitemap gives Google a crawlable path that doesn't depend on script execution.

If you decide to build one, two implementation paths work: a dedicated image sitemap, or adding <image:image> entries inside your existing page sitemap. Either way, you get up to 1,000 image entries per URL block, and the image URLs are allowed to sit on a different domain (a CDN, for instance) from the sitemap file itself, as long as both are verified in Search Console.

One caution worth flagging because outdated tutorials still show it: tags like <image:caption>, <image:geo_location>, <image:title>, and <image:license> are deprecated. Copying old example code that includes them won't break your sitemap, but it won't help either, since Google no longer reads them. Once your image sitemap is built, run it through sitemapcheck.tools to confirm the syntax and the image entries validate before you submit it in Search Console.

Structured data for images: what it actually gets you

This is the section where I see the most overclaiming, even from otherwise solid articles. Structured data is not what gets your image indexed. A plain <img> on a crawlable, indexable page handles that on its own, as covered above. What structured data adds is specific rich-result eligibility on top of basic indexing, and it's worth being precise about which markup does what.

For a product page to be eligible for an image badge or rich result in Google Images at all, Google's documentation requires the image attribute in your product structured data. Separately, and this is the piece most articles blur, the Licensable badge (the label that tells searchers licensing terms are available for an image) requires ImageObject markup that includes contentUrl plus at least one of creator, creditText, copyrightNotice, or license, with license specifically required for the badge itself to appear. Source: Google Search Central, Image licensing metadata.

In plain terms: if you only sell products, the basic image field is what matters for image rich results. If you license or syndicate photography and want the Licensable badge specifically, that's a separate, additional markup requirement. Don't add licensing structured data expecting it to improve basic indexing; it won't, because that's not the problem it solves.

Does image size affect rankings?

Indirectly, yes, and the mechanism is worth understanding rather than taking on faith. There's no documented Google ranking factor called "image file size." What's documented is Core Web Vitals, a set of page experience metrics that Google states are "used by our ranking systems." One of those metrics, Largest Contentful Paint (LCP), measures how long it takes the largest visible element on the page to render, and on most pages, that largest element is an image: a hero banner, a product photo, a header illustration. Source: Google Search Central, Understanding Core Web Vitals.

The "good" threshold for LCP is rendering within 2.5 seconds of the page starting to load, according to Chrome's own web.dev documentation. A bloated, unoptimized hero image is one of the most common reasons a page misses that mark. Source: web.dev, Largest Contentful Paint.

So the honest chain looks like this: heavy images slow LCP, slow LCP can hurt Core Web Vitals, and Core Web Vitals is a documented (Google's own word is "used," not "the primary driver") input into ranking systems. It's not a direct line from kilobytes to position in Google Images. It's a real, if modest and indirect, one.

Google's own guidance also cautions against chasing a flawless Core Web Vitals score purely as an SEO exercise. Get it into good territory, then move on to work with a clearer payoff.

Format choice matters here too: a JPEG or PNG hero image is usually heavier than the same picture saved as WebP at a comparable visual quality, so switching format is often the quickest win before you touch compression settings at all. Our WebP vs JPEG comparison covers when that swap makes sense and when it doesn't, and AVIF goes a step further still. For the actual mechanics of shrinking image weight further without wrecking quality, our guide to reducing image file size covers the practical side; this section is only answering the "why does it matter" question.

The quick-check recap

Run through this in order. Each check is fast, and doing them in sequence stops you from renaming files or adding structured data that couldn't have fixed the actual problem.

• Is the image placed in an <img>, <picture>, or srcset element, not a CSS background?
• Is the page itself indexable (no noindex, not blocked in robots.txt)?
• Does the file have a short, descriptive name, without keyword stuffing?
• Does the image have accurate, non-generic alt text?
• If images load via JavaScript, is an image sitemap in place to guarantee discovery?
• If rich results or licensing badges matter to you, is the relevant structured data present?
• Is the largest image on the page light enough to keep LCP under 2.5 seconds?

Most sites I audit fail on the first two items and assume the problem is the last two. That mismatch is exactly why the order matters.

Check your own images

If you want a faster starting point than manually inspecting every product page, run your URL through imagecheck.tools. It probes every image it can reach, reports real format and file size against what the markup claims, flags missing or weak alt text, and surfaces oversized files that are dragging your LCP down. It won't tell you whether your page is set to noindex or whether robots.txt is blocking a folder, those are separate checks worth running first, but once discoverability is confirmed, it's a quick way to see which of the size and alt text items on this checklist still need attention.

Frequently Asked Questions

Does image file name matter for SEO?

A little, not much. Google's own documentation describes descriptive filenames as giving "very light clues" about an image's subject matter, using my-new-black-kitten.jpg versus IMG00023.JPG as its example. Treat it as a minor signal worth applying when you're already touching a file, not a project worth renaming an entire catalogue for on its own.

How do images get into Google Images?

Google discovers images by crawling indexable pages and finding them placed through genuine HTML image elements: <img>, <picture>, or srcset. Images set only as CSS background-images are excluded from Google Images entirely, and images on a page blocked by noindex or robots.txt won't be found regardless of how they're marked up.

Do images need to be in a sitemap?

No. Image sitemaps are optional and exist to help Google find images it might otherwise miss, most notably images loaded dynamically through JavaScript. If your images sit in standard <img> tags on crawlable pages, a sitemap isn't required for discovery, though it can still be a useful safety net on larger or script-heavy sites.

Does image size affect rankings?

Not as a direct, named ranking factor, but there's a real indirect path. Large images slow down Largest Contentful Paint, which is one of the Core Web Vitals metrics Google states are used by its ranking systems. Keeping your largest on-page image light enough to render within roughly 2.5 seconds supports both page experience and that indirect ranking input, without file size itself being a standalone signal.