Why websites use WebP
Images are often 50% or more of a web page’s total size. Every kilobyte saved makes the page load faster, which matters for visitors on mobile connections and for search rankings, since Google’s Core Web Vitals measure how quickly the main content appears. WebP gives the same visual quality as JPG with noticeably fewer bytes, and it is now displayed by every current browser, which is why most large websites and image CDNs serve WebP by default.
JPG versus WebP in practice
| Feature | JPG | WebP |
|---|---|---|
| Compression efficiency | Baseline | 25–35% smaller |
| Transparency | No | Yes |
| Animation | No | Yes |
| Browser support | Universal | All current browsers |
| Email and office apps | Universal | Inconsistent |
The table shows why the choice depends on the destination. For your own website, WebP is the better format. For email attachments, documents and uploading to third-party services, stick with JPG.
How the conversion works
Each JPG is decoded with MozJPEG’s decoder in a background Web Worker, the EXIF orientation is applied so the image is upright, and the pixels are encoded with libwebp at the chosen quality. Camera metadata is not copied, so GPS coordinates in photos are not published along with your images. Because the work happens on your device, you can convert as many files as you like.
What about quality loss from re-encoding?
Converting from one lossy format to another always re-compresses the image, but the effect is small when you start from a good source. A camera or phone JPG at full resolution converted to WebP at quality 80 looks the same as the original at normal viewing sizes. The risk is with JPGs that were already heavily compressed, such as images saved from social media; converting those can make existing artefacts more noticeable, so use a higher quality setting, around 90, for them.
Tips for web images
- Resize first. A 4000-pixel photo displayed at 1200 pixels wastes bandwidth even as WebP; use Resize Image.
- Use quality 75–85 for content images and 85–90 for large hero photos.
- Keep originals. Store the JPG masters and regenerate WebP versions when you redesign your site.