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Convert WebP to AVIF

A further step down in file size, with transparency intact. Encoded on your own machine — nothing is uploaded.

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How do I convert WebP to AVIF?

To convert a WebP to AVIF, drop the file onto this page and download the AVIF it returns. Everything runs in your browser, so nothing is uploaded. AVIF compresses harder than WebP: on our fixed test image a 247 KB WebP became a 104 KB AVIF, about 58% smaller, with transparency preserved.

How to do it

  1. Open the converter. Open this page in any modern browser. The AVIF encoder downloads on first use and is then cached.
  2. Add your WebP files. Drag them onto the panel or click to choose. Alpha transparency carries through.
  3. Set the quality. 82 is the default. Because the source is already lossy, going much higher mostly stores WebP's artefacts more faithfully rather than improving the picture.
  4. Wait, then download. AVIF encoding is slow by design. It runs in a Web Worker, so the page stays responsive while it works.

At a glance

ConvertsWebP to AVIF
TransparencyPreserved
CompressionLossy — quality is adjustable, default 82
Where it runsIn this browser tab. The file is not uploaded
File size limitNone imposed — your device memory is the ceiling
CostFree
Account neededNo
WatermarkNone
Works offlineUsually after first use, but not guaranteed — there is no offline app

What it actually produces

Measured, not estimated. A procedurally generated 2400×1600 (3.8 MP) test image built to carry photographic entropy: value noise across nine octaves down to near-pixel scale, a dense field of small high-contrast features, a smooth gradient, hard edges and light grain. It is not a photograph — it is reproducible, which a photograph is not. Each figure below comes from running that image through this page.

InputOutputChange
247 KB104 KB58% smaller

Your own files will differ — a photograph, a screenshot and a diagram compress very differently. The point of a fixed image is that the formats can be compared with each other, not that your result will match.

Is the extra step worth it?

On the fixed test image used for every measurement on this site, converting the WebP to AVIF took it from 247 KB to 104 KB — around 58% smaller.

That is a real saving, and on a media-heavy page it compounds. Whether it is worth doing depends on two things: how much you care about encoding time, and whether your audience is fully current.

Convert from the original if you still have it

This is a lossy-to-lossy conversion. The WebP already discarded detail, and encoding it as AVIF discards a little more — and worse, spends bits faithfully reproducing WebP’s own compression artefacts.

If the original PNG or JPG is still available, convert that instead. On our test image, PNG straight to AVIF produced 109 KB from a much better source, against 104 KB from the already-degraded WebP. Nearly the same size, noticeably better picture.

Both keep transparency

AVIF and WebP both support a full alpha channel, including semi-transparent pixels, so cut-out product shots and soft-edged logos convert cleanly in either direction.

Serve both rather than choosing

The strongest option is not to pick. A <picture> element can offer AVIF first and WebP as a fallback, and the browser takes the first one it understands:

<picture>
  <source srcset="photo.avif" type="image/avif" />
  <source srcset="photo.webp" type="image/webp" />
  <img src="photo.jpg" alt="…" />
</picture>

Current browsers get the smallest file, older ones still get something they can render, and nothing breaks.

Questions

Is AVIF actually smaller than WebP?
Yes, by a clear margin. On the fixed test image used here, the same source produced a 247 KB WebP and a 109 KB AVIF. Converting the WebP itself to AVIF gave 104 KB — around 58% smaller than the WebP it came from.
Am I losing quality by converting an already-lossy WebP?
Some, yes. This is a lossy-to-lossy conversion, so a little more detail goes each time. If you still have the original PNG or JPG, converting that directly to AVIF gives a better result than going through the WebP.
Is transparency preserved?
Yes. Both formats support a full alpha channel, including semi-transparent pixels.
Which browsers support AVIF?
Chrome, Edge, Firefox, Opera and Safari, plus their mobile versions. Safari added support in 2022, so AVIF is slightly less forgiving than WebP for audiences on older devices.
Why is AVIF encoding so slow?
AVIF is built on the AV1 video codec, which searches much harder for an efficient encoding than WebP does. That search is where the extra saving comes from.
Should I replace all my WebP images with AVIF?
Only if the bandwidth saving matters more than encoding time and the small extra compatibility risk. Serving both from a picture element and letting the browser choose is better than replacing one with the other.
Is my image uploaded?
No. Decoding and encoding both run in this browser tab. The Uploaded readout beside the result measures the page's outbound traffic, so a successful conversion reads 0 B.
Is there a file size limit?
None imposed. Large images take longer to encode rather than being rejected.
Can I batch convert?
Yes, but AVIF is the slowest encoder on this site. Large batches take real time — work in smaller groups if you want to see progress.
Will there be a watermark?
No. Nothing is added to the image and nothing is paywalled.

About these formats

Sources

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