Convexy

How to convert AVIF to JPG on iPhone

AVIF is the best general-purpose lossy image codec in wide use. It is also the one your older desktop app, print service or upload form is most likely to reject — which is presumably why you are here.

What AVIF is

AVIF is a still image encoded with AV1 — the video codec developed by the Alliance for Open Media (Google, Mozilla, Netflix, Amazon, Apple and others) — stored in a HEIF-style container. It is, in effect, a single intra-frame of an AV1 video.

That makes it a close cousin of HEIC, which is a single intra-frame of an HEVC video in the same style of container. The technical difference is the codec; the practical difference is licensing. HEVC is patent-encumbered, which is why no browser will display a HEIC. AV1 is deliberately royalty-free, which is why browsers adopted AVIF and why it is spreading fast across the web.

On compression it is genuinely excellent — typically 50% or better than JPG at equivalent quality, comfortably ahead of WebP. It also supports transparency, HDR and wide colour.

So why convert it away?

Because being technically superior and being accepted are different things. AVIF is new: browser support is broad now, but a great deal of software is not a browser. Older desktop applications, print shops, some enterprise systems, plenty of upload forms and older phones simply have no AVIF decoder. When one of them refuses your file, JPG is the universal fallback — thirty years old, unencumbered, readable by literally everything.

You almost certainly did not choose AVIF. It arrived because you saved an image from a site that serves AVIF to browsers that support it.

Expect the JPG to be substantially bigger — and slightly worse. This is a lossy-to-lossy re-encode: the AVIF is decoded and re-compressed with a much older, much less efficient codec. You will pay for compatibility twice, in file size and in a small amount of generation loss. At a high quality setting the loss is invisible; the size increase will not be.

Two things that will change

Consider WebP as a middle ground. If the destination is a website or app that rejects AVIF but does support WebP — a large category — WebP keeps the transparency and stays far smaller than JPG. Convexy can write it, using Google's bundled libwebp encoder, since Apple's own frameworks have no WebP writer. Go to JPG only when you need the absolute compatibility floor.

Locally, with no upload

iOS can decode AVIF natively, and Convexy re-encodes with Apple's ImageIO on the device itself. No server, no account, no network request. Metadata is stripped by default; turn that off in Options if you want EXIF and location tags carried over.

How to do it

  1. Bring the AVIF in

    Tap Browse files and pick the .avif from Files, or share it into Convexy from Safari or another app.

  2. Choose JPG

    Convexy shows the formats an AVIF can become — JPG, PNG, HEIC, TIFF, BMP, GIF, WebP, ICO or PDF. Tap JPG for maximum compatibility.

  3. Pick a background if the image has transparency

    JPG cannot hold an alpha channel. Transparent areas are composited onto white unless you choose another colour in Options.

  4. Keep the quality high

    You are already re-encoding an image that has been through one lossy codec. There is no sense compounding the loss to shave off a few kilobytes.

  5. Convert, then save or share

    Check the size comparison — the JPG will be larger, which is the price of compatibility. Save to Photos or Files, or send it straight on.

Common questions

What is an AVIF file?

An image compressed with the AV1 video codec and stored in a HEIF-style container — essentially a single frame of AV1 video. It was developed by the Alliance for Open Media to be royalty-free, which is exactly why browsers adopted it while refusing the patent-encumbered HEIC. It compresses roughly 50% better than JPG and supports transparency and HDR.

Why won't my AVIF file open?

Because the software is older than the format. Browsers handle AVIF well now, but a lot of desktop applications, print services, upload forms and older devices have no AVIF decoder at all. Converting to JPG is the reliable escape hatch — JPG has been universally readable for three decades.

Is AVIF better than JPG?

Technically, by a wide margin — roughly half the size at the same visual quality, plus transparency, HDR and wide colour, none of which JPG can do. Practically, JPG still wins on the only axis that matters when something rejects your file: everything, everywhere, can open a JPG. That is the entire reason this conversion exists.

Will converting to JPG make the file bigger?

Yes, usually a lot bigger. AVIF is a far more efficient codec, so representing the same picture as a JPG at comparable quality takes considerably more bytes. You are trading file size for compatibility. If the destination supports WebP, that is a better compromise — smaller than JPG, and it keeps transparency.

AVIF or HEIC — what's the difference?

Both are single video frames in a HEIF-style container. AVIF uses AV1; HEIC uses HEVC. The decisive difference is licensing: AV1 is royalty-free and browsers support AVIF, while HEVC is patent-encumbered and no browser will render a HEIC. HEIC is Apple's on-device photo format; AVIF is the web's modern one.

Does the JPG keep transparency from the AVIF?

No. JPG has no alpha channel and cannot represent a transparent pixel under any circumstances. Convexy composites transparent areas onto a solid background, white unless you choose otherwise. If you need the transparency preserved, convert to PNG or WebP instead.