PNG is lossless compression with a full 8-bit alpha channel. AVIF is AV1 still-picture encoding, alpha, and far smaller files than JPEG at equal quality. ImageMagick sits between the two, and this page says exactly what happens to a PNG file on the way to becoming an AVIF one.
What runs when a PNG file becomes AVIF
ImageMagick 6.9.12, on a machine we rent and watch. Your PNG file is uploaded once, ImageMagick runs once, the AVIF comes back, and neither file is kept. PNG to AVIF is one of the 3649 pairs that engine was probed on with a real file, which is why it has a page here and why the pairs the probe could not prove do not.
What survives from the PNG into the AVIF
The pixel dimensions of your PNG file. The AVIF comes out the size the PNG went in, because nothing on this path resizes anything.
Transparency. PNG and AVIF both carry a real alpha channel, so a cut-out sent as PNG is still a cut-out as AVIF.
What PNG to AVIF costs you
Nothing measurable, which is rare enough to say plainly. PNG and AVIF carry the same kind of content with the same fidelity, so this pair changes the container and not the picture. What does change is the size, and often by a lot.
If a model is going to read the AVIF
An AVIF file is pixels, and pixels are expensive for a model to read. Handed this AVIF, an assistant spends its budget looking at the picture rather than reading it, and it will paraphrase what it thinks it saw. If your PNG is mostly words, the useful move is to pull the text out of it, not to change which picture format holds it.
PNG to AVIF, measured rather than promised
Running PNG to AVIF against the real engine with a real file, ImageMagick wrote 359 bytes of AVIF in under a tenth of a second, machine otherwise idle. That is one PNG file on one day and not an average, which is why the number is given together with the file that produced it.
The PNG to AVIF verdict was reached by a format signature, meaning at least four bytes unique to the format were found at the right offset. Which check was used matters, because they do not all prove the same thing, and a status code of 200 proves nothing whatsoever about whether the AVIF file has anything inside it.
The same PNG file, sent somewhere else
Other outputs the probe measured out of a PNG file, so the cost of choosing AVIF can be read against something. Sizes do not compare across engines, because each family was probed with its own PNG witness file.
PNG to PDF: 2,536 bytes in under a tenth of a second, verified by a format signature.
PNG to JPG: 1,568 bytes in under a tenth of a second, verified by a format signature.
PNG to WEBP: 370 bytes in under a tenth of a second, verified by a format signature.
PNG to GIF: 3,512 bytes in 0.1 seconds, verified by a format signature.
PNG to TIFF: 1,466 bytes in under a tenth of a second, verified by a format signature.
What we will not pretend about PNG to AVIF
A PNG file over 25 MB is refused before the upload finishes rather than after it, so you do not wait for a rejection.
A PNG to AVIF run that passes 30 seconds is killed, and the ImageMagick process is killed with it. A run left behind would sit on one of the machine's two cores until somebody noticed.
No text is read out of the PNG anywhere on this path. Converting a picture to AVIF never turns it into words, whatever the picture happens to contain.
ImageMagick was not saturated at sixteen simultaneous conversions: it held 47.5 a second while latency moved from 0.22 s to 0.34 s, and the service memory did not move off 51 MB. That is the measured headroom behind PNG to AVIF, not a marketing number.
One PNG file at a time, chosen in the browser. There is nothing else to set up and nothing else on offer.
PNG to AVIF: what people ask
What actually converts my PNG file to AVIF?
ImageMagick does it, 6.9.12, on a machine we rent and watch. Not a browser trick and not somebody else service: the PNG file is uploaded once, ImageMagick runs once, the AVIF comes back, and neither file is kept afterwards.
How long does PNG to AVIF take?
On the file the probe used, ImageMagick took under a tenth of a second and wrote 359 bytes of AVIF. That is one real measurement on one real PNG file, not an average and not a promise about yours: a larger PNG takes longer, and past 30 seconds the run is stopped.
What do I lose going from PNG to AVIF?
The one to know about first: Nothing measurable, which is rare enough to say plainly. PNG and AVIF carry the same kind of content with the same fidelity, so this pair changes the container and not the picture. What does change is the size, and often by a lot.
Does the AVIF come out the same size as the PNG?
The same pixel size, yes: nothing on this path resizes anything, so the AVIF is as wide and as tall as the PNG was. The number of bytes is a different question and usually moves a long way, which is normally the reason for doing this at all.
Is PNG to AVIF free?
There is a free allowance every month, and one PNG to AVIF conversion costs half a credit against it. When the allowance runs out the tool says so and stops, rather than quietly handing you a worse AVIF.