Convert JPG to WebP

Images are usually the heaviest part of a web page, and most of them are still JPG because that is what cameras, phones and stock libraries produce. WebP was released by Google in 2010 as a smaller replacement for exactly those files. Its lossy mode is built on the VP8 video codec, which predicts each block from its neighbors instead of encoding every 8 × 8 block on its own the way JPEG does.

The practical result is fewer bytes for the same picture. On a product page with twelve 150 KB photos, trimming a quarter to a third from each saves several hundred kilobytes per visit, which shows up directly in Largest Contentful Paint, the Core Web Vitals metric that times the biggest image or text block on screen.

Support is no longer a concern for visitors. Chrome has displayed WebP for more than a decade, Firefox since version 65 in 2019, and Safari since version 14 in 2020. The holdouts are outside the browser: email clients, some social platforms that build link previews, and desktop software. That is why the sensible setup serves WebP to browsers and keeps the JPG for everything else.

The <picture> snippet above lets each browser pick the first source it understands, so a visitor on an old browser silently gets the JPG. Keep the width and height on the <img>; they reserve space and stop the layout from jumping while the image loads.

If your site runs on WordPress, version 5.8 and later accept WebP uploads in the media library, so you can upload the converted files directly. Many CDNs can also convert on the fly; this page is for images you want to control by hand, such as a hero banner.

Before publishing, compare total folder size: if the WebP set is not clearly smaller, the JPGs were already compressed hard and converting buys you little. For images that still need a byte budget afterwards, use compress image.