Free converter · Lossy re-encode
Convert PNG to WebP
Short answer
Drop your PNG 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.
Canvas encodes WebP at quality 0.92 (lossy). · Lossy re-encode · Browser-side via Canvas - nothing uploaded.
Key takeaways
- PNG to WebP saved space here: 29,816,949 bytes became 3,561,686 (-88.1%) for a photograph.
- The converter encodes lossy WebP at quality 0.92: SSIM against the fixed RGB reference was 0.981026, so it is not lossless.
- WebP supports transparency, but this opaque-photograph measurement does not establish a size result for transparent artwork.
- For flat graphics and screenshots, results differ from photographs; test your own file.
Measured: PNG 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.
| Input | Input size | WebP size | Change | Result |
|---|---|---|---|---|
| Photo as PNG, opaque | 29,816,949 bytes | 3,561,686 bytes | -88.1% | SSIM 0.981026, yuv420p |
This measurement uses an opaque photograph. Test a transparent source separately before relying on its result.
PNG vs WebP
| PNG | WebP | |
|---|---|---|
| Full name | Portable Network Graphics | WebP (Google) |
| What is inside | Pixels compressed without loss | Lossy or lossless compressed pixels |
| Compression | Lossless | Lossy or lossless |
| Transparency | Transparency supported | Transparency supported |
| Best for | Screenshots, logos and graphics with text | 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. Canvas encodes WebP at quality 0.92 (lossy).
Lossless WebP exists, this converter does not write it
WebP supports both lossy and lossless compression, according to Google's WebP overview, which also says lossless WebP is 26% smaller than PNG and that transparency works in both modes. This converter uses the lossy setting at quality 0.92, which is why a photograph shrank so much more than 26%. If you need pixel-exact output, use ffmpeg -i in.png -c:v libwebp -lossless 1 out.webp or the cwebp tool.
Transparency support
WebP supports an alpha channel, according to Google's WebP overview. This page does not publish a size measurement for a transparent source.
Questions people ask
Is this PNG 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 PNG 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.
How much smaller is WebP than PNG?
For this photograph, 88.1% smaller in our test. For a flat graphic it differs; test your file.
Is PNG to WebP lossless?
Not with this converter: it writes lossy WebP at quality 0.92 (SSIM 0.981026 on this photograph).
Does the WebP keep transparency?
WebP supports an alpha channel, according to Google's WebP overview. This opaque-photograph measurement does not test a transparent source.
Can I get a lossless WebP?
Yes, with ffmpeg -c:v libwebp -lossless 1; this converter does not offer it.
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.