Empirical Responsive Images helps WordPress send each visitor an image closer to the size shown on their screen. Smaller, better-sized images can mean less data to download and faster-looking pages.

Instead of guessing which image sizes your site might need, the plugin learns from real page layouts. When it repeatedly finds a missing size, it creates that thumbnail in the background. It can also create WebP and AVIF versions when your server supports them.

This directly targets common PageSpeed Insights messages such as “Improve image delivery,” “Properly size images,” and “Serve images in next-gen formats.” Results still depend on your theme, original images, cache, hosting, and other plugins.

Why image size matters

A large image may be displayed in a small space. If WordPress has no close match, the browser may download far more image data than it needs.

Empirical Responsive Images gives WordPress more useful choices. Your existing responsive image system stays in place; the plugin fills proven gaps instead of replacing it.

How it works

After a page loads, a small browser check compares displayed images with the sizes already available.
Images with a good match are ignored and send no report.
Missing sizes must be confirmed before any work is scheduled.
WordPress creates the needed image files later, as a background task.
Future visitors can receive a closer image size.

No resizing happens in the visitor’s browser. No image is generated while a visitor waits for the page.

What it can improve

Better-sized responsive images for phones, tablets, laptops, and high-density screens.
New thumbnails for WordPress Media Library images.
Responsive versions of manageable local theme and plugin images.
WebP and AVIF versions when supported by the server.
Better image choices through WordPress’s normal responsive image markup.
Automatic cache refresh after new image files are ready.
Clear status tables under Tools > Responsive Images.
Optional maintenance commands for advanced users.

The plugin keeps existing custom image choices, crops, and picture layouts. It does not send images to a content delivery network (CDN) or outside image service.

Privacy

Automatic learning reports only what the plugin needs to identify a local image and a rounded missing size. It may also include a general screen size and the space used by the image so WordPress can make a better choice next time.

These reports do not store the page URL, visitor identity, IP address, browser details, or referring page. Reports from logged-out visitors and Subscribers do not send cookies.

An optional detailed view is available only to site administrators. It can store combined image measurements and page paths for troubleshooting. Query strings and raw IP addresses are not saved.

Everything stays on your WordPress site. Nothing is sent to an external service.

Settings, learned size records, and generated images remain after uninstall by default. You can enable full cleanup under Tools > Responsive Images before uninstalling.

Protection against abuse

The plugin accepts work only for images that belong to your site and were marked by the plugin. Visitors cannot submit any image URL or invent unlimited custom sizes.

Normal visitors must confirm the same missing size over time. Hard limits on requests, waiting jobs, retries, image size, daily work, and free disk space keep everything under control. Repeated or invalid reports do not gain priority.

Advanced commands

List learned image sizes:

wp empirical-responsive-images sizes

Generate thumbnails and modern image versions:

wp empirical-responsive-images regenerate --batch-size=10

Force a rebuild:

wp empirical-responsive-images regenerate --force