Why convert JPG to WebP?
WebP is an image format made by Google for the web. It uses a newer way of compressing photos than JPG, so the same picture takes fewer bytes. Smaller images mean pages load faster, use less mobile data and score better in speed tests such as Google PageSpeed Insights, which flags “Serve images in next-gen formats” when a site still uses large JPGs.
Google’s own study found that lossy WebP files are 25–34% smaller than JPGs at the same visual quality (measured with the SSIM quality index). Your results depend on the photo, but a site full of product shots or blog photos usually shrinks noticeably.
How this converter works
- Your browser reads each JPG and decodes it into pixels on your device.
- A WebP encoder (libwebp, compiled to WebAssembly) compresses those pixels at the quality you choose.
- The new file appears in the list with its old and new size, ready to download.
Nothing is sent to a server. Once the first photo has converted, the encoder is loaded and you could even go offline and keep converting. The original file name is kept, so beach-01.jpg becomes beach-01.webp, and a batch downloads as one ZIP.
Choosing the quality
The quality slider runs from 50 to 100. Higher means larger files with fewer compression artefacts.
| Quality | Typical use | What to expect |
|---|---|---|
| 90–100 | Photography portfolios, zoomable product images | Files can be close to the JPG size; little gain |
| 75–85 | Blogs, online shops, landing pages | The usual sweet spot: much smaller, looks the same |
| 60–70 | Thumbnails, background images, previews | Smallest files; fine detail softens slightly |
80 is the default because it matches what most image CDNs and WordPress plugins use. If your JPGs were already heavily compressed (for example, downloaded from social media), the WebP may only be a little smaller. Converting again at a higher quality cannot bring back detail that the JPG already lost.
Worked example: how much a page saves
Say a product page shows 12 photos, each 280 KB as JPG, for 3.36 MB in total. If WebP saves 30% at the same quality, each photo becomes about 196 KB:
On a 4G connection at around 10 Mbit/s, 1 MB takes almost a second to download. Multiply that by every visitor and the bandwidth and speed gains add up quickly. To save even more, resize photos to the size they are actually shown at with Resize Image before converting. A 4000-pixel camera photo shown in an 800-pixel column wastes most of its bytes.
Using WebP images on your website
- WordPress (5.8 and later) accepts WebP uploads in the media library like any JPG.
- Shopify, Wix and Squarespace accept WebP uploads, and many convert images to WebP for you when they serve them.
- Plain HTML: use the file like any other image,
<img src="photo.webp" alt="…" width="800" height="600">. If you must support very old browsers, put it inside a<picture>element with a JPG fallback. - Email newsletters: stick with JPG. Several email apps, including some versions of Outlook, still do not show WebP.
When to keep JPG
WebP is great for websites, but JPG is still the safest choice for:
- Printing, and sending photos to print shops or photo labs.
- Government, exam and job portals, which usually accept only JPG or PDF. Use Compress Image to KB for those instead.
- Older software such as some photo viewers, office apps and messaging apps on older phones.
If you receive a WebP and need a JPG, WebP to JPG converts it back in the same private way.
Tips and edge cases
- Screenshots and logos are usually PNG files, not JPG. Use PNG to WebP, which also offers lossless WebP and keeps transparency.
- CMYK JPGs from print workflows are converted to normal RGB colours, which is what browsers show anyway.
- Huge files: phones may run out of memory above roughly 50–100 megapixels. Resize first if a file fails.
- Metadata: EXIF data such as GPS location is not copied, which protects your privacy when you publish photos online.
- Quality looks off? Compare a converted file with the original at 100% zoom. If you see blocky skies or smeared fine textures, raise the quality by 5–10 points and the list updates automatically.