Why does my animated GIF break when I resize it?

Optimised GIFs store partial frames containing only the changed region. Resizing those fragments scrambles the animation. Add -coalesce before the resize to rebuild full frames, and -layers Optimize afterwards.

How do I create an animated GIF from images with ImageMagick?

Put the timing settings before the inputs: magick -delay 8 -loop 0 frame_*.png -layers Optimize output.gif. Zero-pad the frame numbers or the shell will sort them incorrectly.

How do I reduce the file size of a GIF?

Lower the colour count with -colors, disable dithering with +dither, and add -layers Optimize so only changed regions are stored. Dropping every second frame helps further.

What unit is ImageMagick -delay measured in?

Hundredths of a second per frame. A delay of 8 is about 12.5 frames per second. Browsers clamp values below 2 to roughly 10 fps.

ImageMagick animated GIF commands

Build an animated GIF from frames, resize one without breaking the animation, shrink an oversized GIF, and split a GIF into frames. Explains why -coalesce is mandatory.

Build a GIF from frames

magick -delay 8 -loop 0 frame_*.png +dither -colors 128 \
  -layers Optimize output.gif

-delay and -loop must appear before the input frames — they are settings applied to images read afterwards. Put them at the end and they do nothing.

-delay 8 — the unit is hundredths of a second, so 8 is roughly 12.5 fps. Browsers clamp anything below 2 to about 10 fps, so going lower is pointless.
-loop 0 — loop forever. Any other number loops that many times.

Zero-pad your frame numbers. Shell globs sort as text, so frame_10.png comes before frame_2.png and your animation plays out of order. Name them frame_0002.png.

Resize an animated GIF

magick input.gif -coalesce -resize 320x -layers Optimize output.gif

-coalesce is not optional. An optimised GIF does not store complete frames — most frames are just the rectangle that changed since the previous one. Resizing those fragments directly scales the fragments, and the animation turns into visual garbage. -coalesce rebuilds every frame as a full image first; the trailing -layers Optimize puts the size saving back afterwards.

Shrink an oversized GIF

magick input.gif +dither -colors 64 -layers Optimize output.gif

Two levers do most of the work:

Colour count. 256 → 128 → 64 shrinks the palette geometrically. Screen recordings of flat UI survive 64 colours easily; photographic content does not.
-layers Optimize. Stores only the changed rectangle of each frame. On a recording with a static background this alone often halves the file.

+dither turns dithering off. Keep it off for UI recordings and screencasts; turn it on for photographic content where banding would otherwise show.

Dropping frames

If it is still too large, remove every second frame and double the delay:

magick input.gif -coalesce -delete '1--1/2' -set delay 16 \
  -layers Optimize output.gif

Split a GIF into frames

magick input.gif -coalesce frame_%03d.png

Without -coalesce you get the stored difference frames rather than what the animation actually looks like.

Inspect a GIF

magick identify -format '%n frames, %wx%h\n' input.gif

If your source is a video

ImageMagick is the wrong tool. It shells out to ffmpeg anyway and does a poor job of palette selection. Use ffmpeg's two-pass palette filters directly:

ffmpeg -i input.mp4 -vf "fps=12,scale=480:-1:flags=lanczos,palettegen" palette.png
ffmpeg -i input.mp4 -i palette.png -lavfi "fps=12,scale=480:-1:flags=lanczos,paletteuse" output.gif