Free converter · Lossy re-encode
Convert JPG to WebP
Short answer
Drop your JPG file into the converter below and download the WebP file. It runs in your browser with the Canvas API; nothing is uploaded. The file is re-encoded to a lossy WebP at 92% quality by default; transparency is kept.
Both lossy; quality roughly preserved. · Lossy re-encode · Browser-side via Canvas - nothing uploaded.
Key takeaways
- At the converter's fixed quality of 0.92, a JPG to WebP conversion grew: 3,101,063 bytes became 3,567,944 (+15.1%) in our test.
- The conversion re-encodes: SSIM against the fixed RGB reference was 0.979746.
- The exact result depends on the photograph and encoder settings; do not assume WebP saves space after a second lossy encode.
- Convert only if a site wants WebP; otherwise keep the JPG and avoid a second lossy step.
Measured: JPG to WebP
Measured on a NASA public-domain photograph, 3.1 MB, decoded once to a fixed RGB reference, using the same steps this converter runs in the browser (draw to a canvas, JPEG gets a white background, encode at quality 0.92), run in headless Chromium. Other browsers use their own encoders, so sizes can differ. Results describe this photograph.
| Output | Size | Change | SSIM vs the JPG's pixels |
|---|---|---|---|
| This converter: WebP, quality 0.92 | 3,567,944 bytes | +15.1% | 0.979746 |
The original NASA photograph was 3,101,063 bytes at 3840 × 3877 px. WebP is not automatically smaller: its savings depend on the original and quality setting.
JPG vs WebP
| JPG | WebP | |
|---|---|---|
| Full name | JPEG image (.jpg) | WebP (Google) |
| What is inside | Lossy compressed pixels | Lossy or lossless compressed pixels |
| Compression | Lossy | Lossy or lossless |
| Transparency | No transparency | Transparency supported |
| Best for | Photos; the image format every platform documents | Smaller images on websites; social platforms mostly document JPEG and PNG instead |
What you get
A lossy WebP at 92% quality by default; transparency is kept. Both lossy; quality roughly preserved.
How to get real savings
- Try more than one quality value on your own image instead of assuming a fixed browser quality will save space.
- Test two or three quality values on your own photo and compare them at 100% zoom; SSIM has no universal pass mark.
- A JPG that was already saved at a low quality gains little, because the WebP has to encode the JPG's artifacts too.
When to leave it as JPG
Google's WebP overview says lossy WebP images are 25 to 34% smaller than comparable JPEGs at equivalent SSIM quality. That comparison starts from a JPEG and matches quality; this converter instead fixes the WebP quality at 0.92, which on our photo produced about the same size as the JPG. If the destination accepts JPG and you do not need WebP, converting adds a second lossy encode for little gain at this setting.
Questions people ask
Is this JPG to WebP converter free and private?
Yes. It is free, needs no account and runs entirely in your browser, so the file never leaves your device.
Will converting JPG to WebP reduce quality?
Some, because WebP is lossy or lossless and the file is re-encoded. How much depends on the clip and on the quality setting, and at the converter's default setting the loss can be visible, so keep the original. For uploads, the platform re-encodes again anyway.
Is WebP smaller than JPG?
It can be, but this converter's quality 0.92 grew this NASA photograph by 15.1%.
Does JPG to WebP reduce quality?
Yes, it is another lossy encode. Our test scored SSIM 0.979746 against the fixed RGB reference.
Can I change the quality in the converter?
No, it is fixed at 0.92. Use a tool such as ffmpeg or cwebp for other settings.
Does WebP keep transparency?
Yes, WebP supports an alpha channel; JPG does not.
More converters
Sources and how we checked
- MDN: Media container formats
- MDN: Web audio codec guide
- MDN: Image file type and format guide
- FFmpeg documentation: stream copy
- FFmpeg Documentation: ffmpeg (stream selection, -map, -c copy) (read 2026-10-08)
- Google Developers: An image format for the Web (WebP) overview (read 2026-10-08)
- Wikimedia Commons: Buzz salutes the U.S. Flag (NASA, public domain), the photo used for the image measurements (read 2026-10-08)
Reviewed October 8, 2026. What the converter writes was measured with ffprobe on the same FFmpeg build your browser downloads; format descriptions follow MDN's media guides.