Image SEO on a business website is less about ranking pictures in Google Images and more about three jobs in a fixed order. First, make each image readable for search engines. Second, make it light enough not to slow the page. Third, make it your own. Get those right and your photos can bring visits from image search and support the page they sit on.
This guide follows Google’s image SEO best practices and adds what a busy owner needs on top: which fixes to do first, a worked example with one job photo, and a quick way to check the results. If you’re new to search in general, start with our beginner’s introduction to SEO.
What does image SEO cover?
Image SEO covers every signal a search engine uses to understand a picture, plus how fast and reliably that picture loads. Search engines can’t see an image the way you do, so they read its alt text, file name, caption and the text around it.
Image SEO is part of on-page SEO and of page experience. Videos follow similar rules, covered in our guide to optimizing video for search.
Why do images matter for a business site?
Images affect 4 things a business site depends on. For most local firms, speed is the one that hurts first: one uncompressed phone photo can outweigh the rest of the page.
- Visibility, because photos can show in Google Images and next to regular results.
- Relevance, because a clear image beside matching text supports the page’s topic.
- Speed, because images are often the heaviest part of a page and shape its page speed.
- Accessibility, because alt text tells screen reader users what an image shows.
Which image fixes should you do first?
Do the image fixes in the order your site needs them, not in the order a checklist lists them. Find your situation in the table and start there.
| Your situation | Start with | Why |
|---|---|---|
| Pages feel slow on phones | Resize and compress, then lazy-load images below the fold | Oversized files are the usual cause |
| Files are named IMG_4021.jpg and have no alt text | File names and alt text | Google has nothing to read about the picture |
| You sell products or show your finished work | Original photos, captions and structured data with an image | These are the pictures people search for |
| A theme or slider loads images through scripts or CSS | Real img elements, then an image sitemap | Google may never find those images |
| Speed and markup are already fine | A clear preview image for each page | It guides which picture Google can show beside your result |
Our rule of thumb: on any page that loads slowly, fix speed before metadata. A picture nobody waits for helps no one.
Image SEO best practices from Google’s guidance
1. Use real HTML images
Add images with an HTML <img> element and a src attribute. Google doesn’t index images that are only set as CSS background images, so use <img> for any picture you want found.
2. Write good alt text
Alt text is the short description in an image’s alt attribute, and Google calls it the most important image metadata. Describe what the picture shows in plain words that fit the page.
Google warns that filling the alt attribute with keywords counts as keyword stuffing. Write alt=”Plumber replacing a copper pipe under a kitchen sink”, not alt=”plumber cheap plumber best plumbing pipe seo”.
When an image is a link, its alt text works like the link’s anchor text. Decorative images get an empty alt (alt=""). There’s more in our glossary entry on alt text.
3. Give files short, descriptive names
Use a name that says what the image shows, such as black-kitten-on-sofa.jpg, not IMG_4021.jpg or image1.jpg. Google says the file name gives it clues about the subject of the image. Separate words with hyphens, and translate file names on localized sites.
4. Place images near relevant text
Put each image close to the text it illustrates, on a page about the same subject. Captions and nearby headings help search engines understand the picture.
Use the same image URL everywhere the image appears, so it’s cached and crawled once.
5. Choose the right format
Google Search supports images in BMP, GIF, JPEG, PNG, WebP, SVG and AVIF, and the file extension should match the real format. Pick the format by what the image is.
| Format | Best for | Watch out for |
|---|---|---|
| JPEG | Photos of people, places and finished work | No transparency |
| PNG | Screenshots and graphics with sharp edges or transparency | Large files when used for photos |
| WebP | Photos and graphics at smaller file sizes | Some older editing tools don’t open it |
| AVIF | The smallest files at similar quality | Some plugins and editors don’t handle it yet |
| SVG | Logos and icons that stay sharp at any size | Not suited to photos |
6. Keep files small and sharp
Compress every image before you upload it, and resize it to the largest size the page shows. A 4,000-pixel photo displayed at 800 pixels makes every visitor download pixels they never see.
Google’s guidance asks for current optimization and responsive techniques, because images are often the largest part of page weight. Test the page in PageSpeed Insights. Keep images sharp too, because they also serve as thumbnails in results.
7. Serve responsive images
Use srcset or the <picture> element so phones get small files and large screens get larger ones. Always keep an <img> with a src as the fallback.
Set width and height so the page doesn’t jump while images load. Lazy-load images below the fold, but never the main image at the top of the page, because that slows down the part visitors see first.
8. Add an image sitemap if needed
Google usually finds images through normal crawling. If it might miss some, such as images loaded by scripts, list them in an image sitemap or add them to your XML sitemap.
Images served from a CDN can go in the sitemap too. Verify the CDN domain in Search Console so you see its crawl errors.
9. Choose preview images and add structured data
Pick an image that represents the page: a clear subject, high resolution and a sensible aspect ratio. Skip generic logos and pictures full of text.
Point Google to your preferred image with og:image or schema.org properties such as primaryImageOfPage. To qualify for image badges and rich results, structured data needs an image property that matches the page. See schema markup.
10. Skip the title attribute
Google’s image guidance doesn’t ask for the HTML title attribute on images, and it shows as a tooltip only on some devices. Spend that effort on alt text, file names and captions.
11. Mind copyright and trust
Use images you own, have a licence for or create yourself, and credit sources where the licence requires it. Before you reuse a picture, a reverse image search shows where it already appears online.
Your own photos of your team, premises and finished jobs carry something stock pictures can’t: proof that the work is real.
Worked example: one job photo, before and after
This is an illustrative example, not a client case. A plumbing firm adds a photo of a finished bathroom job to its renovation page.
| Element | Before | After |
|---|---|---|
| File name | IMG_4021.jpg | walk-in-shower-grey-tiles.jpg |
| Alt text | Empty | New walk-in shower with grey wall tiles after a bathroom renovation |
| Size | 4,000 pixels wide, straight from the phone | Resized to the widest size the page shows, then compressed |
| Format | JPEG as shot | WebP through srcset, with a JPEG fallback |
| Placement | A gallery page with no text | Next to the paragraph about bathroom renovations, with a caption |
| Loading | Lazy-loaded, although it’s the first image | Loads normally; later gallery images lazy-load |
None of these changes needs a developer. Together they give Google a picture it can read, and the visitor a page that loads.
Image SEO checklist
Run each new page through these 10 checks before you publish it.
- Use
<img>elements with asrc, not CSS backgrounds, for images you want found. - Write alt text that describes the image, without keyword stuffing.
- Use short descriptive file names with hyphens.
- Place each image next to related text, with a caption where it helps.
- Use JPEG, PNG, WebP, AVIF or SVG as appropriate.
- Compress files and serve the right size for each screen.
- Set width and height, and lazy-load images below the fold.
- Add images to a sitemap if Google might not find them.
- Choose a clear representative image for each page.
- Check results in Search Console and PageSpeed Insights.
How do you check your images?
Checking your images takes 5 steps with free tools, plus a crawler if your site has many pages.
- View the page source in your browser and confirm each <img> tag has alt text, a width and a height.
- Run the page through PageSpeed Insights and read its image warnings, such as oversized or unoptimized files.
- Use the URL Inspection tool in Google Search Console to see how Google renders the page.
- Open the Performance report, set the search type to Image, and check impressions and clicks from Google Images.
- On a larger site, run a crawler such as Screaming Frog to list images with missing alt text and oversized files.
Fix the images on your five busiest pages first
Open Search Console, sort your pages by clicks, and run the checklist on the top five. Those are the pages people already see, so every fix there reaches real visitors.
Then add the checklist to your routine for every new page. If you’d rather have someone handle image and speed fixes across the whole site, ask about our SEO services.
Frequently asked questions
Do images help SEO?
Yes, when the images are relevant, well described and fast to load. They can bring visits from Google Images and make a page more useful to the people who land on it. A slow, unlabelled image does the opposite.
Does alt text help rankings?
Alt text helps Google understand both the image and the page, and Google calls it the most important image metadata. Write it for the person who can’t see the picture. Text written that way also reads naturally to Google.
What is the best image format for SEO?
No single format is best for SEO. WebP or AVIF give small files, JPEG suits photos, PNG suits graphics with transparency, and SVG suits logos. Match the format to the image and keep the file small.
How big should images be?
Images should be as small as possible while still looking sharp at the size they’re shown. Resize each image to the largest size the page displays it, then compress it. Use responsive images so smaller screens get smaller files.
Should I use keywords in image file names?
Use words that describe the image. If those words also match what you want the page found for, that’s fine. Stuffing extra keywords into the name adds nothing.
Terms in this guide
