Image SEO: A Practical Checklist for Small Business Websites

Image SEO is the work of making the pictures on your website easy for search engines to find, understand and load quickly. Google Search supports seven image formats (BMP, GIF, JPEG, PNG, WebP, SVG and AVIF), and its documentation calls alt text the most important piece of image metadata. On the speed side, Google’s Core Web Vitals treat a Largest Contentful Paint of 2.5 seconds or less as good, and the largest element on a page is frequently an image. For a small business the practical version is short: use real HTML images, give each one a descriptive file name and honest alt text, size and compress it for the screen it appears on, and keep the main image on the page from loading late. If you would rather have a team handle the wider technical side, 2Marketing’s technical SEO and schema services include Core Web Vitals fixes such as image compression, and the sections below show what that work involves so you can do it yourself or judge any provider.

Image SEO at a glance

• Supported formats: BMP, GIF, JPEG, PNG, WebP, SVG and AVIF, according to Google Search Central
• Discovery: Google finds images in the src attribute of an img element, including inside a picture element, and does not index CSS background images
• Alt text: short, specific, in context, with no keyword lists (Google warns that keyword stuffing can be seen as spam)
• Image sitemap: optional, up to 1,000 images per page entry, useful when images load in ways crawlers may miss
• Speed target: Largest Contentful Paint of 2.5 seconds or less at the 75th percentile of page loads is rated good by web.dev
• Search interest in Canada: about 260 searches a month for “image seo”, with a 12 month range of 50 to 880 (DataForSEO estimate, national figure, not city level)

Key terms in one line each

• Alt text: the alt attribute on an img element, read by screen readers and used by search engines to understand what an image shows
• Largest Contentful Paint (LCP): the time it takes for the biggest visible element, often a hero image, to render
• Responsive images: the same picture offered in several sizes through srcset or a picture element so each device downloads a fitting version
• Image sitemap: an XML sitemap that lists image URLs alongside the pages that use them
• Lazy loading: delaying the download of images until they are near the screen

How much any of this matters differs by site. A restaurant or a retailer that depends on photos has more to gain than a consultancy with a handful of stock images, and a page that already loads quickly may only need better alt text. The figures above are estimates and documented thresholds, not a forecast of traffic, and improving images does not guarantee higher rankings or a place in AI answers.

Key takeaways

• Use plain img elements for any picture you want indexed. Google does not index CSS background images, so a decorative treatment is fine but a product photo set as a background is invisible to image search.
• Alt text should describe the image in the context of the page, in a short sentence. It is for people using screen readers first, and search engines benefit from the same clarity.
• File names give Google only light clues, according to Google’s own guidance. Short descriptive names are still worth the minute they take, and they make your media library searchable for your own team.
• Page speed is the quiet half of image SEO. Oversized images are a common reason a page misses the 2.5 second LCP threshold, and fixing them helps visitors whether or not it moves rankings.
• Do not lazy load the main image at the top of the page. Lazy loading is for images that start off screen.
• Treat reputation, product and team photos as content. Original, relevant images placed next to the text they illustrate give Google and your visitors more to work with than a generic stock image.
• Measure with Search Console and a speed test before and after, and expect changes to take time to show up.

What is image SEO and why does it matter to a local business?

Image SEO is a group of habits that help search engines understand your pictures and help visitors see them quickly. It covers how an image is coded into the page, what it is called, what text describes it, how large the file is and how it is delivered. The goal has two sides. One is visibility in image results and in the visual parts of regular results. The other is a faster, more accessible page, which supports everything else you do in search.

For a local business the case is concrete. People often judge a clinic, a contractor or a restaurant by its photos before they read a word, and a slow page full of heavy photos loses some of them. Images also feed the broader local picture: the photos on your Google Business Profile and on your website tell the same story, so keeping them consistent and well described is part of good local presence. 2Marketing’s local SEO services in Toronto treat website content and profile content as one system for that reason.

Image SEO will not rescue a page with thin content, and it works as a supporting task rather than a strategy on its own. If your pages already answer customer questions well, tidy images remove friction. If they do not, the content comes first.

How does Google find and understand the images on your site?

Google finds images in the src attribute of an img element, even when the element sits inside another element such as a picture tag, and Google’s image SEO guidance states that it does not index CSS images. That single rule explains many missing images: a slider built with background images, or a gallery that loads pictures only through scripts, can hide photos from crawlers even though visitors see them.

Once an image is found, Google learns about its subject from several places at once. The documentation lists the surrounding content of the page, captions and image titles as sources, along with alt text and the file name. It also asks that images sit near relevant text and on pages that are relevant to the picture. In plain terms, a photo of a finished kitchen renovation helps most on a page about kitchen renovations, close to a paragraph that describes the job.

This is also why image work belongs next to your page-level work. The same page needs a clear topic, a sound title and internal links, topics covered in our guide to SEO audit services, and large sites should read how to manage crawl budget if thousands of image URLs are involved.

Which image formats can Google index?

Google Search supports images referenced in the src attribute in these formats: BMP, GIF, JPEG, PNG, WebP, SVG and AVIF. Google also recommends that the file extension matches the actual file type, so a WebP file should end in .webp. Inline Base64 data URIs are allowed, but they make the page itself larger, so they suit tiny icons more than photos.

The right-hand column is general practice rather than a Google rule. Test a few of your own images, because results depend on the picture. A photo with lots of fine texture compresses differently from a flat product shot on a white background.

What should you check first? A practical image SEO checklist

The order below puts the high-impact, low-effort items first. Most small business sites can work through the top half in an afternoon and use the bottom half as a quarterly habit.

How do you write good alt text?

Good alt text is a short, accurate description of what the image shows and why it is on the page. Google’s guidance asks for useful, information-rich text that uses keywords appropriately and fits the context of the page. It also shows a progression from missing alt text, to keyword stuffing, to a short word, to a descriptive phrase such as “Dalmatian puppy playing fetch”. The descriptive phrase is the one it calls best.

The W3C accessibility guidance adds a useful decision frame. Informative images get a brief description that conveys the meaning. Functional images, such as an image inside a button or link, get alt text that states the destination or action. Purely decorative images, or images whose content is already stated in nearby text, get an empty alt attribute (alt=””) so screen readers skip them. For charts and other complex images, put the information in the page text rather than squeezing it into the alt attribute. You can read the full W3C alt text decision tree for the edge cases.

The first weak example tries to hold a service, a city and a price word in one string, which reads badly aloud and falls into the keyword stuffing Google warns about. A good habit is to read your alt text aloud as if you were describing the page to a friend on the phone. If it sounds odd, it probably is.

Should alt text include your target keyword?

Only when the keyword is a natural part of what the image shows. A photo on a page about a furnace repair that shows a technician at a furnace can say so in plain words. Adding a city name to every image does not help a reader, and Google’s guidance points the other way. If the keyword does not describe the picture, leave it out.

What about the title attribute and captions?

Google’s documentation mentions captions and image titles as places it can learn about a picture, so a short caption under an image that carries information is useful to people and search engines alike. The HTML title attribute is a different matter: it appears as a tooltip on desktop only, and it is not a substitute for alt text. Use captions where they help a reader, and skip them on decorative images.

How should you name and place image files?

Google says the file name gives only very light clues about an image’s subject and recommends short, descriptive names, with its own example of my-new-black-kitten.jpg being better than IMG00023.JPG. Hyphens between words are the convention, and generic names such as image1.jpg are called out as unhelpful. Treat this as housekeeping with a small benefit rather than a ranking lever. It makes the media library easier to search, and it keeps the habit consistent for whoever uploads next.

Place images where they belong in the text. A photo that illustrates a paragraph should sit next to that paragraph, because Google reads surrounding content when it works out what an image is about. Reusing the same image URL across pages is also useful, since Google’s guidance suggests a consistent URL for an image used in several places so it can be cached.

Are original photos better than stock images?

There is no ranking rule that says so, but Google’s guidance on helpful content favours original value, and a photo of your own work, team or premises tells a visitor something a stock image cannot. Google also advises choosing images that are relevant and representative for the main image of a page and avoiding generic images such as logos. The practical advice is to use stock images for mood and your own photos wherever a customer is trying to judge you.

How do you keep images from slowing your pages down?

Image weight is a fixable cause of slow pages, and the fix is mostly mechanical. The standard sequence is to resize first, then compress, then choose the format, then deliver the right size to each device. A common mistake is skipping the first step. A photo uploaded at its full camera size and shown in a 600 pixel wide column still makes the visitor download every pixel.

Google’s Core Web Vitals thresholds give a target to work toward. Per web.dev, Largest Contentful Paint is rated good at 2.5 seconds or less, needs improvement between 2.5 and 4 seconds, and poor above 4 seconds, measured at the 75th percentile of page loads and split by mobile and desktop. Images, video posters, background images loaded with url() and blocks of text can all be the LCP element, so check what yours is. See web.dev’s Largest Contentful Paint guide for the details, and our older note on Core Web Vitals for background.

Resize and compress

Resize each image to the largest size at which it is displayed, allowing for high-density screens if you want sharpness on phones. Then compress. Most image editors and many WordPress plugins offer lossy and lossless options. Lossy compression removes some detail the eye rarely misses, and lossless keeps every pixel but saves less. Compare the result at full screen before you publish, because over-compressed photos look smudged and hurt trust more than they help speed.

Use responsive images

The srcset attribute and the picture element let you offer several versions of one image so the browser picks a fitting one. Google’s documentation says to use picture or srcset and to keep an img element with a src as the fallback, because that is what the HTML standard requires and what Google reads. If you use WordPress, check what your theme and image plugin output rather than assuming it is handled, since recent versions of WordPress add sizes and some loading attributes automatically but themes and builders can override them.

Set width and height

web.dev recommends width and height attributes on all img elements so the browser can reserve space before the file arrives. That prevents the page from jumping as images load, which is the layout shift measured by Cumulative Layout Shift. It costs nothing and applies whether or not you lazy load.

Lazy load below the fold, and only there

The loading=”lazy” attribute tells the browser to defer offscreen images. web.dev’s guidance is to load images in the first viewport eagerly, and to use lazy loading for images outside it, and it specifically warns against lazy loading likely LCP images. Read the web.dev lazy loading guide if you use a builder that applies lazy loading to everything. A lazy loaded hero image can delay the very element that sets your LCP, so confirm in a test whether that is happening on your pages.

A simple way to test is to run the page through PageSpeed Insights before and after a change, and to repeat on your phone over mobile data. One test is a snapshot, so run it a few times and look at the pattern rather than a single score. Our guide to a useful monthly SEO report, what an SEO report should include, covers how to track such changes without being misled by one number.

What do image sitemaps and structured data do?

An image sitemap is an XML file that lists image URLs against the pages that use them. Google’s documentation says each page entry can contain up to 1,000 image entries, that image URLs can be hosted on another domain such as a CDN, and that the image domain should be verified in Search Console so you can receive crawl errors. The older caption, title, geo location and licence tags in image sitemaps have been deprecated, so a current sitemap needs only the image location. See Google’s image sitemap documentation for the format.

A sitemap is optional for most small sites, because Google usually finds standard img elements without help. It earns a place when images are loaded by scripts, served from a CDN on another domain, or hard to reach through normal links. WordPress SEO plugins often include images in the regular post sitemap, so check what yours already does before adding anything.

For structured data, Google says you can specify a preferred image for a landing page with schema.org primaryImageOfPage, with mainEntity or mainEntityOfPage that includes an image property, or with the og:image meta tag. It advises picking an image that is relevant and representative, avoiding generic images such as logos or images containing text, and avoiding extreme aspect ratios. Where a structured data type supports it, the image property is required for eligibility for a badge and rich result in Google Images. Eligibility is not a promise of a rich result, and markup should always match what is visible on the page. If you want help with schema, our technical SEO team handles structured data, covering types such as Article, Product, LocalBusiness and FAQ.

How do you handle image SEO in WordPress?

WordPress makes the basics easy and some of the details easy to miss. Every upload has an alt text field in the media library, a title, a caption and a description. Set alt text for informative images there or in the block editor, so it travels with the image wherever it is reused. Many themes also print the featured image alt text in their own way, so view the page source or an accessibility checker and confirm what is actually output.

Be careful with automation. A bulk alt text tool can fill a thousand empty fields in minutes, and it can also write a thousand slightly wrong descriptions. Treat generated text as a draft and review the pages that matter most. For the wider question of how web development choices affect speed, see the role of web development in website performance and SEO, and if you are rebuilding, web design in Toronto is where image handling gets decided at the template level.

How do you check how your images are performing?

Start with Google Search Console. The Performance report lets you filter by search type, and image results can be viewed separately from web results, so you can see impressions and clicks that come from image search for your pages. The Search Console Performance report help explains the metrics and filters. Remember that Search Console data covers a limited window by default, so export or note figures if you want to compare over time.

Then use a speed test such as PageSpeed Insights on your most important pages. Look at which element is the LCP, how large the images are compared with their display size, and whether any image is flagged as offscreen but loaded early. Fix the biggest items first, retest, and repeat. Problems can creep in after a redesign, a new slider plugin or a batch of uncompressed uploads, so put a reminder in the calendar.

If you are not sure where to start, a full technical review will cover images alongside everything else. Our SEO competitor analysis guide also shows how to compare your pages with the ones that rank for your terms, which can reveal how competitors present and describe their images. And if you want a quick read on your site’s overall visibility, the free local AI SEO report is the lightweight place to start, a form-based request that a specialist reviews.

Does image SEO matter for AI search and answers?

Google’s guidance on AI features says that to appear as a supporting link in AI Overviews or AI Mode a page must be indexed and eligible to be shown with a snippet, and that no special optimizations or extra markup are required. Images follow the same logic: a page with crawlable images and clear surrounding text is easier for any system to understand, but nothing in the documentation promises that image changes will lead to citations. Read the AI features and your website documentation for the current wording. If you want the bigger picture, our comparison of SEO and generative engine optimization explains where the two overlap, and the generative engine optimization services in Toronto page describes how 2Marketing approaches it.

Which industries get the most from image SEO?

Any site with a visual decision gets some benefit. The examples below are common categories and the image types that usually carry the most weight. They are general observations, not performance claims.

Whatever your industry, take care with people in photos. Use images of staff and customers only with permission, and avoid exposing private information in screenshots. That is both good practice and a trust signal.

What mistakes should you avoid?

• Putting key photos in CSS backgrounds. Google does not index CSS images, so any photo you want in image search should be an img element.
• Using the same alt text on every image. Repeated text adds no information and makes pages tiring to use with a screen reader.
• Filling alt text with keywords. Google’s guidance warns this can cause a site to be seen as spam, and it makes pages worse for visitors.
• Lazy loading the hero image. It can delay the element that decides your LCP.
• Uploading images at camera size. Resize before upload, or let your platform generate sizes and check that it does.
• Blocking image files in robots.txt. Google notes that robots.txt must not block crawling of images you want indexed.
• Using text in images for important content. If a heading or offer lives only inside a picture, search engines and screen readers may miss it, so put the words in the page as well.
• Taking photos from other sites. Use images you have the right to use, and keep a record of licences for stock images.

When should you hire help, and what should you ask?

Alt text, file names and compression are jobs many owners can do themselves. Help tends to pay off when the site is large, when images load through custom code, or when speed scores stay poor after the basics. A developer or technical SEO can then fix template-level issues such as lazy loading, srcset output and LCP priority in one change instead of one image at a time.

Questions worth asking any provider include: which pages and images will you review first, how will you measure the change, which parts need developer time, and what happens to the work if we change themes. Prices for this kind of work vary a lot by site size and platform, so ask for a written quote and a clear scope. 2Marketing’s technical SEO page does not list prices, and it offers a free technical check through the contact page, or you can book a free 30 minute consultation.

A simple order of work for the next month

If the list above feels long, here is a sequence that fits a busy owner. In the first week, run your five most important pages through a speed test and note the LCP element and the size of the largest images. In the second week, fix those images by resizing, compressing and setting width and height, and make sure the hero image is not lazy loaded. In the third week, write or improve alt text and file names for the images on the same pages. In the fourth week, check Search Console and retest the speed, then decide whether a sitemap, CDN or developer help is justified. Repeat the cycle on the next group of pages after that.

Keep a short log of what you changed and when, because improvements in search data often show up slowly and it helps to connect cause and effect. If a page’s results do not move, the cause may be the content or the competition rather than the images, which is why the SEO audit and reporting posts linked above are worth reading alongside this one.

Frequently asked questions

Related reading

• Google Business Profile optimization: a practical checklist
• SEO audit services: what they include, what they cost and how to choose
• SEO reporting: what a useful monthly report should include
• SEO competitor analysis: a step-by-step process for local businesses
• Technical SEO and schema services