Free GIF to AVIF converter

A GIF describes an image through a colour table. The file carries a list of at most 256 colours and every pixel points to one entry on that list. This is how the GIF89a specification, published by CompuServe on 31 July 1990, sets it out.[1] One entry can be marked as transparent, and pixels holding that number become invisible. A single file also holds many frames, which is how the format shows short animations.

The format itself is three years older, from 1987, and the entry numbers are written by lossless LZW compression.[2] Lossless means here that unpacking returns exactly the numbers that were written. Cutting the image down to 256 colours happens earlier, while the file is being made, and stays in it.

AVIF writes the image with the AV1 video encoder. The AV1 Image File Format specification, version 1.2.0 of 16 October 2025, carries the image at 8, 10 or 12 bits per channel and writes transparency as a separate auxiliary stream.[3] A pixel gets its full colour stated directly, so the number of colours in the image has no ceiling written into the format.

AVIF files open in Chrome from version 85, Firefox from 93, Safari from 16.1 and Edge from 121.[4] Everything that happens during conversion follows from this difference: AVIF works with what the GIF file carries, so it receives exactly as many colours as the colour table held. The gain is the compression itself, because the same pixels written by the AV1 encoder take up markedly less space.

A photo 1200 by 900 pixels, saved as a GIF with a full table of 256 colours, weighs 707,911 bytes. After conversion at the starting quality of 80 percent the same image comes out as an AVIF file of 97,246 bytes. The queue prints “86% less” next to it. We took the measurement on 6 September 2026 in Chromium 151.

A flat graphic behaves differently. The same 1200 by 900 pixels, but sixteen colours and large single-colour areas, gives 7,522 bytes as a GIF. The AVIF result has 11,283 bytes, half as much again. LZW compression writes long runs of repeated numbers in a few bytes, while the AV1 encoder splits the image into blocks and adds a header of its own.

The third case is a graphic with a transparent background. The GIF file weighed 4,533 bytes and the AVIF result 24,085 bytes. Transparency sits in an AVIF file as a separate image written alongside the main one, so on a small graphic that addition weighs more than the image itself.

Three measurements give one rule for choosing. On photographs and richly coloured images the AVIF file comes out several times smaller. On simple graphics with a handful of colours the GIF stays smaller, and conversion then serves another purpose: keeping every image on the site in one format. The measured weights of all four cases are gathered in the table of file kinds.

The converter draws the image from the GIF file on the browser canvas and hands its pixels to the AVIF encoder. The canvas will not write an AVIF file on its own: a browser that does not know the requested format writes a PNG instead and says nothing about the swap.[5] That is why the file is assembled by libavif compiled to WebAssembly, the same encoder Squoosh uses.[6] The image stays on your device the whole time.

The slider in the Set AVIF quality section takes values from 60 to 95 percent and starts at 80. Image dimensions stay as they were, and you can change them in the image editor beforehand. Transparency carries over to the AVIF file as an alpha channel. The queue takes single files up to 100 MB, and above that it shows the message “File is too large (max 100 MB).”

From a file with animation the converter saves the first frame. Such a file gets the note “Animated file — the first frame is saved.” in the queue, so you see it before you click Convert. An animation of twelve frames, 480 by 360 pixels, weighed 975,752 bytes in the measurement, and the AVIF result 8,409 bytes — the weight of a single image.

The finished AVIF file carries the image alone, because the conversion works on the pixels drawn on the canvas. The queue gives the weight before and after conversion, separately for each file and for the whole batch.

The MDN guide gives browser support for AVIF: Chrome from version 85, Firefox from 93, Safari from 16.1 and Edge from 121.[4] On a website the format therefore reaches almost every visitor today.

When a file is going to someone whose software you do not know, a format with wider support serves better. You can save the same image as a PNG with the GIF to PNG converter or as a JPG with the GIF to JPG converter. The way back is handled by the AVIF to GIF converter, which writes the image into a table of 256 colours again. Every other image converter is gathered in the Format conversion section.