PDF is a frozen page layout with no heading structure a machine can rely on. 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 PDF file on the way to becoming a GIF one.
What runs when a PDF file becomes GIF
ImageMagick 6.9.12, on a machine we rent and watch. Your PDF file is uploaded once, ImageMagick runs once, the GIF comes back, and neither file is kept. PDF 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 PDF into the GIF
The pixel dimensions of your PDF file. The GIF comes out the size the PDF went in, because nothing on this path resizes anything.
What PDF to GIF costs you
Scalability. PDF describes shapes, GIF stores a grid of pixels, and the engine rasterises at 150 dots per inch on the way across. That density is a deliberate choice: at the 72 dpi ImageMagick defaults to, an A4 PDF page comes out 595 pixels wide and reads as a failed conversion. Enlarge the GIF afterwards and it blurs, because there is nothing left to redraw from.
Colour depth. GIF holds 256 colours at most, so a photographic PDF gets quantised and its gradients band.
The PDF text layer. A PDF usually carries selectable text; this path treats the page as a picture and paints it, so what comes out is an image of the page rather than its words.
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 PDF is mostly words, the useful move is to pull the text out of it, not to change which picture format holds it.
PDF to GIF, measured rather than promised
Running PDF to GIF against the real engine with a real file, ImageMagick wrote 9,463 bytes of GIF in 0.1 seconds, machine otherwise idle. That is one PDF file on one day and not an average, which is why the number is given together with the file that produced it.
The PDF 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 PDF file, sent somewhere else
Other outputs the probe measured out of a PDF 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 PDF witness file.
PDF to DOCX: 23,905 bytes in 0.9 seconds, verified by a format signature.
PDF to EPUB: 26,909 bytes in 0.9 seconds, verified by a format signature.
PDF to JPG: 5,782 bytes in 0.1 seconds, verified by a format signature.
PDF to PNG: 1,294 bytes in 0.1 seconds, verified by a format signature.
PDF to WEBP: 906 bytes in 0.1 seconds, verified by a format signature.
PDF to TXT: 219 bytes in 0.8 seconds, verified by reading the text back.
Other ways into GIF, and what they measured
Among the published routes into GIF, PDF is the tenth largest output of the 19 measured. The witness files differ, so this ranks the probe run and not your document.
JPG to GIF: 3,487 bytes in 0.1 seconds.
3GP to GIF: 164,004 bytes in 0.1 seconds.
AVI to GIF: 173,720 bytes in 0.2 seconds.
BMP to GIF: 3,799 bytes in 0.1 seconds.
FLV to GIF: 173,530 bytes in 0.1 seconds.
What we will not pretend about PDF to GIF
A PDF file over 25 MB is refused before the upload finishes rather than after it, so you do not wait for a rejection.
A PDF 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 PDF 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 PDF to GIF, not a marketing number.
One PDF file at a time, chosen in the browser. There is nothing else to set up and nothing else on offer.
PDF to GIF: what people ask
What actually converts my PDF 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 PDF file is uploaded once, ImageMagick runs once, the GIF comes back, and neither file is kept afterwards.
How long does PDF to GIF take?
On the file the probe used, ImageMagick took 0.1 seconds and wrote 9,463 bytes of GIF. That is one real measurement on one real PDF file, not an average and not a promise about yours: a larger PDF takes longer, and past 30 seconds the run is stopped.
What do I lose going from PDF to GIF?
The one to know about first: Scalability. PDF describes shapes, GIF stores a grid of pixels, and the engine rasterises at 150 dots per inch on the way across. That density is a deliberate choice: at the 72 dpi ImageMagick defaults to, an A4 PDF page comes out 595 pixels wide and reads as a failed conversion. Enlarge the GIF afterwards and it blurs, because there is nothing left to redraw from.
What pixel size does the GIF come out at?
Whatever 150 dots per inch makes of your PDF, and that density is a decision rather than a default. A PDF carries shapes and page dimensions, never pixels, so a scale has to be fixed before a single pixel is drawn. If you need another size, the PDF is the file to go back to: of the two it is the only one that still knows the shapes.
Is PDF to GIF free?
There is a free allowance every month, and one PDF 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.