Free converter · Lossy re-encode
Convert AVIF to WebP
Short answer
Drop your AVIF 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; transparency is kept.
Nothing is uploaded: the photos are decoded and saved in your browser. The converted file does not carry the original's metadata, such as the date or location.
AVIF to WebP at quality 0.92. · Lossy re-encode · Browser-side - nothing uploaded.
Key takeaways
- Expect a bigger file: the WebP was 1.0 to 2.8 times the size of the AVIF in our five tests, for example 82.0 KB became 135 KB.
- It is a second lossy step: at the default quality 0.92 the results scored SSIM 0.968 to 0.987 against the decoded AVIF.
- The AVIF's own quality sets the size: the same portrait saved at CRF 20 (155 KB) gave a 156 KB WebP, and at CRF 40 (42.7 KB) a 120 KB WebP.
- Decoding took 17 to 50 ms for pictures of 0.5 to 1.4 megapixels.
- Several files can be converted at once, and nothing is uploaded.
Measured: AVIF to WebP
Measured in headless Chromium with the converter's own code (src/lib/heic-convert.ts). Three public domain NASA and archive scans were reduced to 1060 pixels wide and saved as AVIF with libaom at constant rate factor (CRF) 30, and the portrait also at CRF 20 and CRF 40, since a lower CRF is higher quality. Each AVIF was opened in the converter and saved at its defaults: JPG and WebP at quality 0.92, PNG lossless. SSIM compares each result with the pixels the browser read from the AVIF (1.0 would be identical). Other browsers use their own decoders and encoders, so sizes can differ.
| AVIF file | Pixels | AVIF | WebP | Against the AVIF | SSIM | Decode |
|---|---|---|---|---|---|---|
| Portrait, AVIF quality CRF 30 | 1060 × 1320 | 82.0 KB | 135 KB | 1.7 times | 0.974 | 50 ms |
| Portrait, higher quality (CRF 20) | 1060 × 1320 | 155 KB | 156 KB | 1.0 times | 0.968 | 47 ms |
| Portrait, lower quality (CRF 40) | 1060 × 1320 | 42.7 KB | 120 KB | 2.8 times | 0.975 | 29 ms |
| Photo, CRF 30 | 1060 × 1070 | 165 KB | 265 KB | 1.6 times | 0.981 | 43 ms |
| Document scan, CRF 30 | 1060 × 440 | 46.6 KB | 71.9 KB | 1.5 times | 0.987 | 17 ms |
The size of the WebP follows the picture, not the AVIF: the photo with the biggest AVIF (165 KB) gave 265 KB, and the small document scan 71.9 KB.
How the AVIF's own quality sets the size
The same portrait was saved as AVIF at three qualities. A lower CRF means higher quality and a bigger AVIF, and the bigger the AVIF, the more detail there is for the converter to write out.
| AVIF | AVIF size | WebP size | SSIM |
|---|---|---|---|
| Portrait, lower quality (CRF 40) | 42.7 KB | 120 KB | 0.975 |
| Portrait, AVIF quality CRF 30 | 82.0 KB | 135 KB | 0.974 |
| Portrait, higher quality (CRF 20) | 155 KB | 156 KB | 0.968 |
From CRF 40 to CRF 20 the AVIF grew 3.6 times and the WebP grew 1.3 times: the WebP is much less sensitive, because it is written at its own fixed quality.
AVIF vs WebP
| AVIF | WebP | |
|---|---|---|
| Full name | AV1 Image File Format | WebP (Google) |
| What is inside | Pictures compressed with the AV1 video codec | Lossy or lossless compressed pixels |
| Compression | Lossy or lossless | Lossy or lossless |
| Transparency | Transparency supported | Transparency supported |
| Best for | Small photographs on websites; MDN lists it as supported by Chrome, Edge, Firefox, Opera and Safari | Smaller images on websites; social platforms mostly document JPEG and PNG instead |
What you get
A lossy WebP at 92% quality; transparency is kept. AVIF to WebP at quality 0.92.
When to convert AVIF to WebP
- A site, form or app rejects AVIF.
- You need a file that older software opens.
- You are sending the picture to someone whose viewer does not read AVIF.
Free tools:Convert any image to JPGConvert any image to PNGConvert any image to WebPCompress an image to a target size
When to keep the AVIF
AVIF was much smaller than every other format in our tests. If the destination accepts it, keep the AVIF: converting makes the file bigger and, for JPG and WebP, adds a second lossy step.
Questions people ask
Is this AVIF 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 AVIF to WebP reduce quality?
A little, because WebP is lossy or lossless and the file is re-encoded. For uploads, the platform re-encodes again anyway.
How do I convert AVIF to WebP?
Choose the AVIF file above and download the WebP. It runs in your browser, with several files at once if you like.
Why is the WebP bigger than the AVIF?
AVIF compresses photographs much better than older formats. Our WebP files were 1.0 to 2.8 times the size of the AVIF they came from.
Does converting AVIF to WebP lose quality?
A little. Both are lossy, so this is a second lossy step. At the default quality our results scored SSIM 0.968 to 0.987 against the decoded AVIF.
Which browsers can open AVIF?
MDN's image guide lists AVIF as supported by Chrome, Edge, Firefox, Opera and Safari. The converter uses your browser's own decoder.
Is my image uploaded?
No. The conversion runs in your browser.
What happens to transparency?
WebP keeps transparency.
Can I convert an animated AVIF?
Only the first frame is converted.
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
- MDN: Image file type and format guide (read 2026-10-09)
- FFmpeg Encoders Documentation: libaom-av1 (the encoder that made the test files) (read 2026-10-09)
- Wikimedia Commons: Portrait of Neil Armstrong (NASA, public domain), one of the pictures used (read 2026-10-09)
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.