About converting PNG to WebP
WebP was designed to replace both PNG and JPG on the web. It supports lossless compression and an alpha channel like PNG, but encodes them far more efficiently - typically around 26% smaller than an equivalent PNG, and more on images with large flat areas.
That size difference is why this conversion shows up in performance audits. Images are usually the heaviest thing on a page, and Largest Contentful Paint is often an image, so converting PNGs to WebP is one of the few changes that improves Core Web Vitals without touching application code.
Browser support is no longer a concern: every current browser renders WebP, including Safari since version 14. If you still need to support genuinely old clients, serve WebP through a picture element with a PNG fallback, and the browser will pick whichever it can display.
Frequently asked questions
- Does WebP keep transparency like PNG?
- Yes. WebP supports a full alpha channel, so transparent backgrounds survive the conversion intact. This is the main reason to choose WebP over JPG when you need a smaller file but cannot lose transparency.
- How much smaller is WebP than PNG?
- Around 26% smaller on average for lossless WebP, and considerably more on images with large areas of flat colour such as logos, screenshots and UI exports. Photographic content saved as lossy WebP shrinks far more again.
- Do all browsers support WebP?
- Yes, every current browser displays WebP, including Safari from version 14 onwards. For very old clients, serve the WebP inside a picture element alongside a PNG source so the browser falls back automatically.