Convert WebP to AVIF — the next compression step
You already made the jump from JPG to WebP. AVIF is the logical next step — the same visual quality at 20-30% fewer bytes. This converter decodes your WebP files and re-encodes them to AVIF entirely inside your browser. No upload, no server, no account required.
Convert to AVIF →Why convert WebP to AVIF?
If you already switched your site from JPG to WebP, you know the compression gains were real. AVIF takes that logic one step further. At matched perceptual quality, AVIF files are typically 20-30% smaller than WebP. For a site already serving WebP images, that is not a rounding error — it is a meaningful reduction in bandwidth cost and page weight. AVIF is built on the AV1 video codec, which benefits from a decade of research in perceptual coding that WebP's VP8 roots simply don't have access to. If your audience is using modern browsers and your images are pre-encoded assets rather than dynamically generated thumbnails, the case for moving to AVIF is straightforward.
What you lose and what you gain
Both WebP and AVIF are lossy codecs by default. Converting one lossy format into another always compounds a small amount of generation loss — detail that WebP discarded during its first encode cannot be recovered. In practice, going from WebP at quality 75 to AVIF at quality 75 is visually indistinguishable in blind tests on photographic content. The re-encoding cost is real but small. What you gain is the file size reduction: 20-30% fewer bytes at parity quality. The tradeoff you feel most is encode time — AVIF encoding is computationally expensive. A single phone photo may take 5-15 seconds to encode in a browser. That is fine for one-off conversions, but build pipelines converting hundreds of images should account for this and process in advance, not on-the-fly per request.
How to convert WebP to AVIF
The entire process runs locally in your browser. The WebP is decoded using a libwebp WebAssembly build and re-encoded using a libavif WebAssembly build. No files leave your device:
- Click "Convert to AVIF →" at the top of this page, or drag your WebP file onto the drop zone on the homepage.
- ConvertMyPic decodes the WebP using libwebp compiled to WebAssembly — the same library that powers Chrome's own WebP decoder. A preview of your image appears almost instantly since WebP decoding is fast.
- The decoded bitmap is passed to libavif, also compiled to WebAssembly, which re-encodes it to AVIF. Expect this step to take 5-15 seconds for a typical smartphone photo — AVIF encoding is CPU-intensive by design, as the codec trades encode time for exceptional compression efficiency.
- Click the download button. Your AVIF file saves to your Downloads folder with the extension swapped — image.webp becomes image.avif.
- Need to tune quality or enable lossless mode? Open /convert directly to access the quality slider, lossless toggle, and advanced options before downloading.
File size comparison: WebP vs AVIF at various quality levels
Numbers from a real 4032x3024 iPhone 15 Pro photo (coastal landscape, 12.2 MP). The WebP source was encoded at quality 75. AVIF outputs were encoded from the same decoded bitmap at the quality levels shown.
| Format | Quality | File size | Visual notes |
|---|---|---|---|
| WebP (source) | 75 | ~720 KB | Original, no visible artifacts |
| AVIF | 90 | ~620 KB | Slightly smaller than WebP; excellent quality |
| AVIF | 75 | ~330 KB | Best quality/size balance; 54% smaller than WebP |
| AVIF | 50 | ~175 KB | Aggressive compression; soft on fine detail |
| AVIF lossless | — | ~3.4 MB | Pixel-perfect; use only for graphics or archival |
When to convert, and when to stay on WebP
Converting WebP to AVIF makes the most sense when you are shipping pre-encoded static assets to a modern audience. If your web analytics show that the bulk of your traffic comes from Chrome 85+, Firefox 93+, or Safari 16+, AVIF is already supported for all those users. CDNs like Cloudflare Images and Fastly support AVIF delivery natively, so the conversion can slot directly into your existing asset pipeline. Stay on WebP when: your server needs to encode images on-the-fly per request — AVIF's slow encode time makes real-time transcoding impractical without dedicated hardware acceleration. Also stay on WebP when older Safari traffic is still significant for your audience — Safari added AVIF support in version 16 (released September 2022), so Safari 15 and earlier users will see a broken image unless you provide a WebP or JPG fallback in a <picture> element. The safest pattern for mixed audiences is to serve AVIF to browsers that accept it and WebP as the fallback, which is exactly what the <picture> srcset pattern enables.
Under the hood: which codecs are used
WebP decoding is handled by libwebp, the reference implementation maintained by Google at chromium.googlesource.com/webm/libwebp. ConvertMyPic compiles it to WebAssembly via Emscripten so it runs entirely in your browser — the same underlying library that Chrome uses to render WebP images natively. AVIF encoding is handled by libavif, the reference encoder and decoder maintained by the Alliance for Open Media at github.com/AOMediaCodec/libavif. libavif wraps the libaom AV1 codec for encoding. Both libraries run in a Web Worker so the main thread — and your browser's UI — stays responsive during the encode. The WASM modules are cached by the service worker after the first page load, so subsequent conversions work offline.
FAQ
Do my files get uploaded anywhere?
No. The entire conversion runs in your browser using WebAssembly. Open your browser's Network tab during a conversion — you will see zero outbound requests beyond the initial page load. There is no server to upload to.
What is the maximum file size?
Browser memory is the practical limit. Typical smartphone WebP files (under 5 MB) convert without issue on any modern device. Very large files — multi-megapixel WebPs over 20 MB — may require a desktop browser with sufficient RAM. If memory runs out, you will see a clear error rather than a silent crash.
Does the tool preserve transparency (alpha channel)?
Yes. Both WebP and AVIF support alpha channels. A WebP with a transparent background will produce an AVIF with the same transparency intact. No manual configuration is needed — alpha preservation is automatic.
Does this work offline?
Once the page has loaded once, the service worker caches both the app and the WebAssembly modules. Subsequent conversions work with no network connection — that's why the app is installable as a PWA on both desktop and mobile.
How does this compare to CloudConvert or Squoosh?
CloudConvert uploads your file to their servers. ConvertMyPic does not have a server — your WebP never leaves your device. Squoosh is also browser-based and uses the same codec libraries; ConvertMyPic adds a simpler drag-and-drop flow and PWA offline support.
Why does AVIF encoding take so long compared to WebP?
AVIF encoding is computationally expensive by design. The AV1 codec runs exhaustive rate-distortion optimization to achieve its superior compression — that analysis takes CPU time. WebP encoding is much faster because its VP8 codec uses simpler heuristics. Expect 5-15 seconds per photo in a browser; the same encode on a server-side libavif with multiple threads is significantly faster. This is why AVIF is best treated as a build-time pre-encode, not an on-the-fly operation.
What is AVIF browser support in 2026?
As of 2026, AVIF is supported in Chrome 85+, Edge 121+, Firefox 93+, and Safari 16+. Combined, these cover well over 90% of global web traffic. The main gaps are very old mobile browsers and some in-app WebViews on Android. Check caniuse.com/avif for current data.
How do I add a WebP fallback for older Safari users?
Use the HTML <picture> element with multiple <source> tags. Put the AVIF source first, then the WebP fallback: <picture><source type="image/avif" srcset="image.avif"><source type="image/webp" srcset="image.webp"><img src="image.jpg" alt="…"></picture>. Browsers try sources in order and use the first one they support.
Does AVIF lossless mode make sense for photos converted from WebP?
Rarely. AVIF lossless encodes the exact pixel values of the decoded bitmap — which already carries the lossy artifacts from the original WebP encode. The result is a much larger file (3-4x the lossy AVIF size) that is pixel-perfect to the WebP decode but not to the original scene. Lossless AVIF is best reserved for graphics, screenshots, and assets that originated as PNGs.
Will converting WebP to AVIF improve image quality?
No. Re-encoding never recovers detail that was discarded in a previous lossy encode. Converting WebP to AVIF at a higher quality setting produces a larger file that preserves the WebP decode faithfully, but it cannot restore detail the WebP codec removed. For the best AVIF output quality, start from a lossless source such as PNG or RAW whenever possible.