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WebP to AVIF converter

Convert WEBP images to AVIF format

No watermarkFree & unlimited
All processing happens in your browser. No data is sent to any server.

Both formats were built for the web and both keep transparency, so this is one of the few conversions that costs almost nothing structurally. The question is whether it is worth doing. AVIF usually squeezes a photograph further than WebP at the same perceived quality, sometimes by a wide margin, but it encodes far more slowly and it is written here only by Chromium browsers. On flat illustration the picture reverses: a lossless WebP can already be smaller than what AV1 produces, so it pays to compare on your own images.

Key facts about WebP to AVIF converter

Key facts about WebP to AVIF converter
What happensThe WebP is decoded by the browser and the pixels are re-compressed as an AV1 intra frame inside a HEIF container.
Encoder availabilityChromium browsers write real AVIF. Firefox and Safari decode it but cannot encode, so the canvas hands back PNG bytes with an .avif name.
AlphaCarried across intact - AVIF stores transparency in a separate plane, so cut-outs and soft edges are preserved.
Generation lossA lossy WebP re-encoded as AVIF is a second lossy pass; a lossless WebP source gives the encoder clean input and a better result.
Typical savingPhotographic content commonly drops another 20-40 percent below the WebP at quality 90; flat graphics may not shrink at all.
Encode timeSeconds per image against milliseconds for WebP - AV1's search is where the extra compression comes from.
AnimationAn animated WebP loses its timeline; the canvas supplies one frame and the output is a still image.
MetadataNothing is transferred. EXIF or XMP stored in the WebP stops at the canvas, and the AVIF contains pixels only.
Decode supportChrome 85, Firefox 93, Safari 16.4, macOS Ventura Preview and Windows 11 with the AV1 extension.

What happens to your file

Both codecs involved are already inside your browser: its WebP decoder produces the pixels and its AV1 encoder consumes them through a canvas.toBlob call with the image/avif type. Nothing is fetched to make this work and nothing is sent while it runs, which is also why the tab becomes busy during a large batch - your processor is doing the compression that a conversion service would otherwise bill for.

About this tool

  1. 1

    Open the page in Chrome or Edge

    A Chromium browser is required for genuine AVIF output; elsewhere the download will quietly contain PNG data.

  2. 2

    Add the WebP files

    Up to twenty per run. Photographic sources benefit most, so start there if you are testing the gain.

  3. 3

    Choose a quality

    Default 90 is a safe comparison point. AVIF holds detail well below that, so 75 is worth trying for delivery assets.

  4. 4

    Convert and compare the sizes

    The result shows the before and after bytes. If the saving is negligible, the WebP was already efficient for that content.

Specs & compatibility
Input and outputTakes .webp only (image/webp) and returns .avif with the image/avif type; any other extension is refused before decoding.
Conversion pathWEBP to AVIF runs in three steps: an <img> element decodes the WebP and passes frame one to the canvas; the pixels land on a 2D canvas in this tab; then canvas.toBlob with the image/avif type returns the finished file.
Browser supportThe WebP side needs Chrome 32, Firefox 65, Edge 18 or Safari 14 to decode, while writing the AVIF needs a Chromium browser, since Firefox and Safari return PNG bytes under the .avif name.
Controls for this pairA 30 to 100 quality slider (steps of five, default 90) drives the AVIF encode, max-dimension presets from 3840 down to 200 px resize the WEBP first, and the strip-metadata toggle is moot on this pair.
Batch, caps and namingTwenty WEBP files per run at 500 MB each; one result downloads as a single AVIF, several as converted-avif-files.zip, zipped by JSZip 3.10 in page memory.
Device ceilingThe canvas caps it: past roughly 16,384 px a side Chromium refuses the bitmap and iPhone Safari gives up sooner, so an oversized WEBP fails before any AVIF bytes exist.
  • Run one representative image through first: whether AVIF beats WebP depends heavily on the picture, and a whole batch is a slow way to find out.
  • Lossless WebP graphics often stay smaller as WebP - test flat artwork rather than assuming the newer format wins.
  • Offer AVIF first and WebP second in a picture element; the browser picks what it can decode and you keep full coverage.
  • Downscale before encoding, since AV1 cost scales with pixel count and an oversized source wastes most of the encode time.
  • Squeezing the last bandwidth out of a site whose images are already served as WebP.
  • Building an AVIF variant of an asset set for a picture element with a WebP fallback.
  • Measuring the real-world saving AVIF would bring before changing a build pipeline.
For photographs, usually yes - a further 20 to 40 percent at comparable quality is common, because AV1's prediction and transform tools are more sophisticated. For flat graphics, screenshots and line art the advantage narrows or disappears, and lossless WebP frequently wins outright. Testing one file from each category is the only reliable answer.
Yes. AVIF stores alpha as an auxiliary image alongside the colour planes, so transparent regions and anti-aliased edges come through as they were in the WebP. This is one of the conversions where nothing about the image structure has to be given up.
AV1 intra coding tries many more block partitions and prediction modes than WebP's VP8 coding does, and that search is the source of the extra compression. Several seconds for a large image is normal, and a batch of twenty will occupy your browser for a while, since the work happens on your machine.
A little. The AVIF encoder has to reproduce whatever artifacts the WebP encoder already introduced, which wastes bits and can compound softening. Where the original PNG or camera file still exists, encoding AVIF from that gives a cleaner and usually smaller result than going through the WebP.
They can display AVIF but not create it, and the canvas specification says an unsupported output type falls back to PNG. The download will therefore be a PNG carrying an .avif extension - larger than expected and not actually AVIF. Use a Chromium browser for this conversion.

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