Image SEO: How to Make Your Pictures Help You Rank

Why images matter for SEO

Image SEO sounds technical, but the idea is simple. You give your pictures clear names, small file sizes, and honest labels so they load fast and search engines understand them. Most owners skip this. So a little effort goes a long way.

Here is the first reason it matters. Images are usually the biggest thing your page has to load. On more than 70% of webpages, the largest element in the first view of the screen is an image (web.dev, 2024). When that image is heavy, your page feels slow, and slow pages lose customers. In one well known study, a 0.1 second improvement in mobile load time raised conversion by 8.4% for retail sites and 10.1% for travel sites (web.dev, 2020).

The second reason is visibility. Your pictures can show up in Google Images, which is a whole extra place customers can find you. To get there, Google needs to understand each image, and it leans on the file name, the alt text, and your sitemap to do it. For the bigger picture on how search works, read what is SEO, then come back here for the image part.

Give every image a descriptive file name

Your camera names files like IMG_4821.jpg. That tells Google nothing. So rename the file before you upload it, and describe what is actually in the shot.

Good file names are short, lowercase, and use hyphens between words. For example, blue-running-shoes.jpg beats IMG_4821.jpg, and georgetown-cafe-interior.webp beats photo2-final-FINAL.png. Google recommends descriptive file names because they help it work out what the image is about (Google, 2024).

A natural keyword usually appears on its own when you describe the picture honestly. So do not force it. Avoid stuffing words that have nothing to do with the image, and do not use spaces or odd characters in the name. One clear, human name per file is all you need.

Write helpful alt text

Alt text is the short description attached to an image. The best part is that the same text does two jobs. It helps people who use screen readers, and it helps Google understand the picture. Get it right once and you cover both.

This is a real gap on most sites. Across the web, 45% of image elements have no alt text at all (Web Almanac, 2024). Yet Google calls alt text the most important attribute for an image (Google, 2024). So writing it puts you ahead of nearly half the web for free.

How to write it well

Describe the image in a short, plain sentence, the way you would tell a friend who cannot see it. Aim for roughly 10 to 125 characters. Do not start with "image of," because screen readers already announce that it is an image. Furthermore, do not jam in keywords. If a picture is purely decorative, leave the alt text empty so screen readers skip it. For more on this kind of accessible build, see how to make a website mobile friendly.

Compress and use a modern format

Most slow pages have one thing in common. They serve huge, uncompressed images. So the single biggest speed win for many small business sites is shrinking the pictures.

Start with the format. For most sites, WebP is the safe default. Google reports that WebP lossy images are 25 to 34% smaller than comparable JPEG images, and WebP lossless images are 26% smaller than PNGs (Google, 2024). AVIF can be even smaller and is worth using when your tools support it. Both load faster than the old JPEG and PNG files you probably have now.

Then compress. Run each image through a compression tool, or let your site builder do it on upload. You will often cut the file size by more than half without any visible drop in quality. Do this once for every image and your whole site speeds up.

Size images right and use responsive images

A common mistake is uploading a giant photo and letting the browser shrink it on screen. The visitor still downloads the giant file. So resize the image to the largest size it will actually appear before you upload it.

Next, go responsive. A responsive image lets the browser pick a smaller version for a phone and a bigger one for a desktop, so nobody downloads more than they need. This matters because phones are where most people land, and the typical mobile page already contains 13 image elements (Web Almanac, 2024). Yet only about 42% of images use the responsive srcset feature, so most sites are still serving one heavy size to everyone.

The good news is you rarely set this up by hand. Modern site builders and image tools add responsive versions for you. The thing to check is that your images carry a width and height so the layout does not jump as they load. If your site struggles on phones, that is a build issue, and our web design service handles it.

Load above-the-fold images eagerly, lazy-load the rest

Lazy loading delays an image until a visitor scrolls near it. As a result, the page opens faster because it only loads the pictures people can actually see. It is a great tool, but only when you point it at the right images.

The lazy-load-your-hero mistake

Here is the trap. Plenty of sites lazy-load every image, including the big one at the top of the page. That image is usually your largest visible element, so delaying it makes the page feel slower, not faster. In fact, only about 9.5% of those top images use native lazy loading, and that is the right call (Web Almanac, 2024).

So the rule is simple. Load the image at the top of the page eagerly, the moment the page starts. Then lazy-load everything below the fold. Most site tools let you flip this with a single setting per image, and getting it right is one of the easiest speed wins you can make. It also fits the broader work in our on-page SEO checklist.

Add images to your sitemap

A sitemap is a file that lists your pages so search engines can find them. You can add your images to it too, which helps Google discover pictures it might otherwise miss, such as ones loaded with code.

Google supports image entries in your sitemap and recommends them to help your images get found (Google, 2024). The good news is you almost never write this by hand. Most site builders and SEO plugins generate an image sitemap for you, so the task is usually just turning the feature on and confirming it is there. Keeping it current is part of regular upkeep, which we cover in our website maintenance checklist.

A quick image SEO checklist

Here is the whole guide in one table. Run through it for each important image on your site, and you have covered the parts that actually matter.

Work through it once for your homepage and top pages, then make it a habit for every new image. For more practical guides, browse the Seed Light blog or see our SEO services.