51.8% of Websites Send Phones the Same Image Files as Desktop Computers

A visitor opens a local bakery's website on her phone over a mobile connection. The homepage photo was exported 2,000 pixels wide for a large desktop screen, and her phone displays it 400 pixels wide. The phone downloads the whole file anyway, and the page sits half-loaded while it does.

Responsive images fix that. A small piece of image code called srcset lets a site offer several sizes of the same picture, so a phone picks a small file and a large screen picks a large one. Without it, every device downloads the biggest version. Images are often the heaviest part of a homepage, so the difference shows up directly in how fast the page loads, and page speed affects both how many visitors stay and how Google ranks the page.

51.8% of homepages with images offer no choice of sizes, just over half the web. The surprise is who does worst: the most visited sites. 60.7% of the top 10,000 websites and 62.8% of websites ranked 10,000 to 1 million serve one size to every device, against 51.2% of the smaller sites outside the top million.

We used the public HTTP Archive crawl from September 2026, which loads millions of website homepages the way a phone would. For the 14,706,316 homepages with at least one image, we checked whether any image on the page offers more than one size through srcset, the standard code for responsive images. A homepage counts as one-size when none of its images do.

We then grouped homepages by how popular their website is, using Google's Chrome UX Report, which ranks sites by real visits from Chrome users: the top 10,000 websites, websites ranked 10,000 to 1 million, and websites outside the top million, where most small business sites sit.

That is 7,613,336 homepages. On each of them, a phone on a mobile connection downloads image files sized for the largest screen the designer planned for. A hero photo exported at 2,000 pixels wide and shown on a 400-pixel phone screen wastes most of the data it downloads, which slows the page at the moment a visitor decides whether to stay.

The other 48.2% of homepages use srcset on at least one image, offering phones a smaller file for some of their pictures.

The web's biggest sites have the largest budgets and development teams, so they should handle images best. They do not. 60.7% of the 10,000 most visited websites serve one image size to every device, and websites ranked 10,000 to 1 million do worst of all at 62.8%, nearly 12 points above sites outside the top million.

Larger sites are more often built on custom code, where responsive images have to be written in by a developer on purpose, image by image. Smaller sites are more often built on platforms such as WordPress, which adds srcset automatically to any image inserted through its standard image block. The platform does the work the custom build leaves to people.

Websites outside the top million have the lowest rate, 51.2%, but that is still one homepage in two. And because they make up almost all of the web, they account for almost all of the one-size homepages: 7,163,087 of the 7,613,336, or 94%, belong to sites outside the top million.

This is where small business websites live, and where the cost of a slow page is felt most directly: a local customer on a phone, looking for a phone number or an opening time, waiting for a large photo to load first. On a WordPress site, a missing srcset usually means images were added through a page builder widget, a slider or custom HTML that skips WordPress's own image handling.

Run your homepage through Google's free PageSpeed Insights and look for the warning "Properly size images". If it flags your hero or gallery images, the fix is either responsive image code or smaller exports. On WordPress, insert images with the standard image block so srcset is added for you, and check that your page builder's image widget does the same. On other platforms, upload images no wider than they will display, which for most full-width photos is about 2,000 pixels.

Then convert large photos to a modern format such as WebP or AVIF, which are much smaller than JPEG at the same quality, and lazy-load images below the first screen so the phone downloads them only when the visitor scrolls. Together, these steps often cut a homepage's weight substantially.

If your site was built before phones were the main way customers found you, responsive web design services can rebuild image handling, layout and loading for the screens your visitors actually use.

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