HEIC is what an iPhone writes unless you tell it not to: HEVC compression inside an ISO container, about half the size of the JPEG it replaced. GIF is a palette of at most 256 colours, all-or-nothing transparency, and animation. ImageMagick sits between the two, and this page says exactly what happens to a HEIC file on the way to becoming a GIF one.
What runs when a HEIC file becomes GIF
ImageMagick 6.9.12, on a machine we rent and watch. Your HEIC file is uploaded once, ImageMagick runs once, the GIF comes back, and neither file is kept. HEIC to GIF 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 HEIC into the GIF
The pixel dimensions of your HEIC file. The GIF comes out the size the HEIC went in, because nothing on this path resizes anything.
What HEIC to GIF costs you
Colour depth. GIF holds 256 colours at most, so a photographic HEIC gets quantised and its gradients band.
If a model is going to read the GIF
A GIF file is pixels, and pixels are expensive for a model to read. Handed this GIF, an assistant spends its budget looking at the picture rather than reading it, and it will paraphrase what it thinks it saw. If your HEIC is mostly words, the useful move is to pull the text out of it, not to change which picture format holds it.
HEIC to GIF, measured rather than promised
Running HEIC to GIF against the real engine with a real file, ImageMagick wrote 2,918 bytes of GIF in 0.1 seconds, machine otherwise idle. That is one HEIC file on one day and not an average, which is why the number is given together with the file that produced it.
The HEIC to GIF 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 GIF file has anything inside it.
The same HEIC file, sent somewhere else
Other outputs the probe measured out of a HEIC file, so the cost of choosing GIF can be read against something. Sizes do not compare across engines, because each family was probed with its own HEIC witness file.
HEIC to PDF: 94,782 bytes in under a tenth of a second, verified by a format signature.
HEIC to JPG: 1,666 bytes in under a tenth of a second, verified by a format signature.
HEIC to PNG: 1,403 bytes in under a tenth of a second, verified by a format signature.
HEIC to WEBP: 416 bytes in under a tenth of a second, verified by a format signature.
HEIC to TIFF: 90,264 bytes in under a tenth of a second, verified by a format signature.
Other ways into GIF, and what they measured
Among the published routes into GIF, HEIC is the number 17 largest output of the 19 measured. The witness files differ, so this ranks the probe run and not your document.
HEIF to GIF: 2,918 bytes in 0.1 seconds.
ICO to GIF: 3,799 bytes in 0.1 seconds.
MKV to GIF: 164,734 bytes in 0.1 seconds.
MOV to GIF: 164,004 bytes in 0.1 seconds.
MPG to GIF: 184,860 bytes in 0.1 seconds.
What we will not pretend about HEIC to GIF
A HEIC file over 25 MB is refused before the upload finishes rather than after it, so you do not wait for a rejection.
A HEIC to GIF 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.
Until the end of August this machine could not read a HEIC at all, and reported the opposite. ImageMagick declared HEIC readable, but libheif carried only its AV1 plugins, which serve AVIF; the HEVC decoder was absent, and a HEIC decoded quietly as something else. The plugin was installed on the 30th, and that is the whole reason this pair exists.
The HEIC to GIF proof used a file genuinely encoded in HEVC, and that detail is not pedantry: ImageMagick refuses to write HEIC and hands you a PNG under that name if you ask it to, so a HEIC forged for the test would have made a false result look like a true one. The GIF it produced was 2,918 bytes, recognised by a format signature.
No text is read out of the HEIC anywhere on this path. Converting a picture to GIF 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 HEIC to GIF, not a marketing number.
One HEIC file at a time, chosen in the browser. There is nothing else to set up and nothing else on offer.
HEIC to GIF: what people ask
What actually converts my HEIC file to GIF?
ImageMagick does it, 6.9.12, on a machine we rent and watch. Not a browser trick and not somebody else service: the HEIC file is uploaded once, ImageMagick runs once, the GIF comes back, and neither file is kept afterwards.
How long does HEIC to GIF take?
On the file the probe used, ImageMagick took 0.1 seconds and wrote 2,918 bytes of GIF. That is one real measurement on one real HEIC file, not an average and not a promise about yours: a larger HEIC takes longer, and past 30 seconds the run is stopped.
What do I lose going from HEIC to GIF?
The one to know about first: Colour depth. GIF holds 256 colours at most, so a photographic HEIC gets quantised and its gradients band.
Does the GIF come out the same size as the HEIC?
The same pixel size, yes: nothing on this path resizes anything, so the GIF is as wide and as tall as the HEIC 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 HEIC to GIF free?
There is a free allowance every month, and one HEIC to GIF 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 GIF.