PNG is lossless compression with a full 8-bit alpha channel. 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 PNG file on the way to becoming a GIF one.
What runs when a PNG file becomes GIF
ImageMagick 6.9.12, on a machine we rent and watch. Your PNG file is uploaded once, ImageMagick runs once, the GIF comes back, and neither file is kept. PNG 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 PNG into the GIF
The pixel dimensions of your PNG file. The GIF comes out the size the PNG went in, because nothing on this path resizes anything.
What PNG to GIF costs you
Colour depth. GIF holds 256 colours at most, so a photographic PNG 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 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 GIF, measured rather than promised
Running PNG to GIF against the real engine with a real file, ImageMagick wrote 3,512 bytes of GIF in 0.1 seconds, 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 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 PNG file, sent somewhere else
Other outputs the probe measured out of a PNG 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 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 TIFF: 1,466 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, PNG is the number 14 largest output of the 19 measured. The witness files differ, so this ranks the probe run and not your document.
MP4 to GIF: 164,004 bytes in 0.2 seconds.
WEBP to GIF: 4,744 bytes in 0.1 seconds.
PDF to GIF: 9,463 bytes in 0.1 seconds.
JPG to GIF: 3,487 bytes in 0.1 seconds.
3GP to GIF: 164,004 bytes in 0.1 seconds.
What we will not pretend about PNG to GIF
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 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.
No text is read out of the PNG 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 PNG to GIF, 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 GIF: what people ask
What actually converts my PNG 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 PNG file is uploaded once, ImageMagick runs once, the GIF comes back, and neither file is kept afterwards.
How long does PNG to GIF take?
On the file the probe used, ImageMagick took 0.1 seconds and wrote 3,512 bytes of GIF. 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 GIF?
The one to know about first: Colour depth. GIF holds 256 colours at most, so a photographic PNG gets quantised and its gradients band.
Can I make an animated GIF this way?
No. One PNG file goes in and one still GIF comes out. A PNG holds a single image, and nothing here assembles several files into a sequence: what you get is that image in a GIF wrapper, with the 256 colours GIF allows.
Is PNG to GIF free?
There is a free allowance every month, and one PNG 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.