PageSpeed Insights keeps telling you to "serve images in next-gen formats," your Lighthouse score won't budge past a certain point, and every performance plugin you've tried mentions WebP without really explaining what to do about it inside WordPress specifically. You know WebP is smaller than JPEG and PNG — what's less clear is whether WordPress already handles it, whether you need a plugin, and what happens to the thousands of images already sitting in your Media Library.
The good news is that WordPress has supported WebP natively since version 5.8, so part of this is already solved for you. The part that isn't solved automatically — converting your existing image library and handling the rare browser that doesn't support WebP — is what this guide walks through.
WordPress has supported uploading and displaying WebP images natively since version 5.8 — no plugin needed for new uploads. What native support doesn't do is convert your existing JPEG and PNG library or add fallback handling, which is where a plugin like Imagify, ShortPixel, or WebP Express comes in. For most sites, the fastest path is: let WordPress handle new WebP uploads natively, and use a plugin to convert everything already in your Media Library.
How WebP works in WordPress
Since WordPress 5.8, WebP is treated as a first-class citizen in the Media Library. You can drag a WebP file into Media > Add New, or upload it directly through the Image block, and WordPress will accept it exactly like a JPEG, PNG, or GIF — no extension or third-party code required.
That native support depends on your server's image processing library. WordPress uses either GD or Imagick to generate the thumbnail sizes it needs (thumbnail, medium, large, and so on), and one of those libraries has to support WebP for uploads to work. Nearly every modern WordPress host meets this requirement out of the box, but lossless WebP with full alpha transparency has historically depended on Imagick specifically, since GD's WebP support has been more limited.
The important limitation to understand: native support is about using WebP files you already have — it is not a converter. WordPress will not automatically turn your existing JPEG and PNG images into WebP. For that, you need either a plugin or a host-level optimization feature, both of which we cover below.
Why WebP matters for your WordPress site
WordPress sites are especially image-heavy — featured images, product photos, theme graphics, logos — which makes image weight one of the highest-leverage places to improve performance:
- It's the single biggest lever for Core Web Vitals. Images typically make up close to half of total page weight on a WordPress site, so converting them to WebP is often the fastest way to improve Largest Contentful Paint.
- It directly answers a PageSpeed Insights warning. The "serve images in next-gen formats" recommendation you see in Lighthouse and PageSpeed Insights is specifically asking for formats like WebP.
- It reduces hosting and CDN costs. Smaller media libraries mean less storage and bandwidth, which matters on WordPress sites with large product catalogs or years of blog images.
- It's now a one-time setup, not ongoing manual work. Once native support and a conversion plugin are in place, every future upload is handled automatically.
Step-by-step: setting up WebP on WordPress
- Confirm your host supports WebP. Check Tools > Site Health > Info > Media Handling in your WordPress dashboard — it lists whether your server's GD or Imagick library supports WebP. Nearly all modern hosts pass this check by default.
- Try a native upload first. Upload a single WebP file through Media > Add New to confirm it works end to end before rolling out changes site-wide.
- Choose a conversion method for your existing library. Decide between a WordPress plugin (Imagify, ShortPixel, WebP Express, WebP Converter for Media) or a host-level feature like Cloudflare Polish or Kinsta's built-in image optimization, if your host offers one.
- Run a full Media Library conversion. Most plugins offer a bulk optimization tool that walks through your existing images and generates WebP versions alongside the originals.
-
Enable automatic fallback. Confirm your plugin is set to serve the WebP version to supporting browsers and the original JPEG/PNG to the rest, typically using the HTML
<picture>element — this is usually on by default. - Set new uploads to convert automatically. Enable the plugin's "auto-optimize on upload" setting so every future image gets a WebP version without manual work.
- Re-run PageSpeed Insights or Lighthouse. Confirm the "serve images in next-gen formats" warning has cleared and check your new Largest Contentful Paint score.
Common mistakes when adding WebP to WordPress
1. Assuming native support means your old images are already converted
WordPress 5.8+ lets you upload new WebP files, but it does nothing to the JPEG and PNG images already sitting in your Media Library. If you skip a conversion plugin entirely, everything published before you enabled WebP stays untouched.
2. Skipping the fallback and assuming every visitor sees WebP
Browser support for WebP is around 98–99% globally in 2026, which is high but not universal. Most plugins add a fallback automatically at no real cost, so there's little reason to disable it — a small number of visitors on older software will otherwise see broken images.
3. Running multiple conversion plugins at once
Stacking two image-optimization plugins (for example, a caching plugin's built-in WebP feature alongside a dedicated conversion plugin) can create duplicate files, conflicting `.htaccess` rules, or images that fail to load. Pick one conversion method for your site.
4. Not checking server requirements before switching hosts or PHP versions
WebP support depends on your server's GD or Imagick configuration, and lossless WebP specifically depends on Imagick in many setups. If you migrate hosts or downgrade PHP, re-check Site Health to confirm WebP support didn't quietly break.
Real-world examples
These are representative results from converting a WordPress Media Library from JPEG/PNG to WebP using a conversion plugin:
The pattern across most WordPress sites is consistent: the conversion itself is nearly invisible to visitors, but the effect on page weight and load time is immediate.
Native support vs plugins vs host-level conversion
There are three distinct ways WebP ends up on a WordPress site, and most sites end up using more than one at the same time.
| Method | Handles new uploads | Converts existing library | Fallback included | Setup effort |
|---|---|---|---|---|
| Native WordPress (5.8+) | Yes | No | No | None |
| Conversion plugin (Imagify, ShortPixel, WebP Express, WebP Converter for Media) | Yes | Yes | Yes, usually automatic | Low – install & run bulk convert |
| Host-level / CDN (Cloudflare Polish, Kinsta Image Optimization) | Yes | Yes, on the fly | Yes | Very low – toggle setting |
Convert your images to WebP before uploading — free
If you'd rather prepare images before they ever touch your Media Library, the Rebrixe Image Converter runs entirely in your browser. Convert JPEG or PNG to WebP, or go the other direction for compatibility — your images are never uploaded to a server. No account, no file size limit, no watermarks.