WordPress doesn’t convert images to WebP automatically. Upload a JPEG or PNG to the media library and WordPress stores and serves it exactly as-is — no format conversion happens without a plugin to handle it. This matters because WebP images run significantly smaller than JPEG or PNG equivalents, often 25–35%, with no visible quality difference — smaller images mean faster page loads, lower bandwidth, and better PageSpeed Insights scores. For most WordPress sites, this is one of the quickest performance wins available.
WebP, or the Newer AVIF Format — Which Actually Matters in 2026
Worth a direct comparison before picking a tool, since this has genuinely shifted: WebP still has the broadest compatibility (97%+ of browsers), but AVIF — the newer, more aggressively compressed format — now covers roughly 93–95% of global browser usage too, close enough that it’s a real contender rather than a bleeding-edge risk. AVIF files typically run 20–30% smaller than WebP at comparable quality, and support HDR and wide colour gamut, which WebP doesn’t. The tradeoff: AVIF encoding is more computationally demanding, a real consideration on shared hosting with a large image library and limited processing headroom.
The practical 2026 consensus is a hybrid: serve AVIF as the primary format with WebP as a fallback (and JPEG below that) using the <picture> element, giving modern browsers the smallest possible file while keeping older ones fully covered. That’s genuinely worth setting up for a site prioritising every last bit of speed — but it needs more than a single plugin toggle to implement properly. For most sites, WebP alone through a straightforward plugin remains the practical default: zero extra setup complexity, near-universal support, and the bulk of the available speed win already captured. Treat AVIF as the next upgrade once WebP is solidly in place and there’s appetite for a slightly more involved setup, not the mandatory first step.
Setting Up WebP
Converter for Media handles this well — free, well-maintained, no third-party account or API key needed, conversion running server-side via the GD or Imagick library the host already provides. It bulk-converts the existing media library in one click, automatically converts new uploads going forward, keeps original files untouched while serving WebP via server-side redirection to supporting browsers, falls back to the original format otherwise, and can revert instantly if needed. Image URLs never change — the plugin creates separate WebP versions and redirects requests transparently.
Install from Plugins → Add New, then under Settings → Converter for Media: leave the conversion method as GD or Imagick (whichever the server supports — an error here means checking with the host which library is actually available), confirm “Convert images uploaded in the future” is enabled, and leave WebP quality at the default 80 unless smaller files are specifically needed (drop to 75) or visible quality loss shows up on specific images (raise it back). Run the Bulk Optimization on the same settings page — the plugin works through the library in batches, taking a few minutes on a site with hundreds of images; leave the page open until it finishes. Confirm it’s actually working by right-clicking an image on the live site, opening it in a new tab, and checking the URL ends in .webp — or use Chrome DevTools’ Network tab, filtered to Img, and check the Type column reads webp after a reload.
The bulk conversion is easy to skip by accident — activating the plugin alone only affects new uploads; the existing library, usually the majority of the site’s images, stays unconverted until the bulk optimizer actually runs. WebP conversion reduces file size but does nothing for filenames or alt text — see optimising images for SEO for that separate piece. Running LiteSpeed Cache already? It has its own image optimisation under LiteSpeed Cache → Image Optimization, which also handles WebP conversion — use either that or Converter for Media, never both on the same site.
Image URLs genuinely don’t change after conversion — Converter for Media uses server-side redirection (.htaccess on Apache, Nginx config otherwise) to silently serve the WebP version when a browser requests the original URL, so nothing in existing posts or pages needs updating. Deactivating the plugin without first reverting can leave images returning 404 errors on some server configurations, since the redirect rules it added stay behind — use its revert option before switching to a different solution, not after.
Already running an image optimisation plugin that includes WebP conversion — Imagify and ShortPixel both do — running a second WebP conversion tool alongside it is unnecessary; check what’s already installed before adding another. For a WooCommerce store with a large catalogue genuinely wanting AVIF alongside WebP, Converter for Media’s Pro version adds AVIF conversion and offloads processing to external servers, reducing the load a bulk conversion would otherwise put on shared hosting — the practical route to the hybrid AVIF-plus-WebP setup described above without needing to build the <picture> element fallback logic by hand.
Etienne Basson works with website systems, SEO-driven site architecture, and technical implementation. He writes practical guides on building, structuring, and optimizing websites for long-term growth.