Compress a GIF on Mac (and Get Under Upload Limits)

A GIF stores each frame as an indexed image of at most 256 colors, with only simple compression between frames. It has no video codec. A four-second clip at 15 frames per second is 60 separate pictures. File size scales with width times height times frame count, so those three numbers are your levers.

Install ffmpeg once with Homebrew (brew install ffmpeg), then run:

ffmpeg -i input.gif -vf "fps=10,scale=320:-1:flags=lanczos,split[a][b];[a]palettegen[p];[b][p]paletteuse" output.gif

fps=10 keeps ten frames a second. scale=320:-1 sets the width to 320 pixels and keeps the proportions. The palettegen and paletteuse pair builds a custom 256-color palette for this clip, which looks better than the default one. Change 320 and 10 until the file is small enough.

Expect to lose some smoothness and sharpness. A GIF that is a screen recording of text will tolerate 10 fps. A fast action clip will look choppy.

My test file was a synthetic 640 x 360 GIF, 60 frames at 15 fps, 959,307 bytes. A synthetic pattern is not a real recording, so treat the percentages as indicative.

The MP4 was the smallest at the original size and frame rate, because video codecs compress between frames and GIF does not. Many sites that say they accept GIFs actually convert them to video. If the destination takes MP4 or WebM, send that instead. For the reverse, see converting a GIF to MP4 on Mac.

Limits change, so check the current number in the service’s own help page before you aim for it. The method is the same whatever the limit is:

1. Halve the width first. Halving width and height cuts pixels to a quarter.
2. Drop to 10 fps, then 8 if it is still too large.
3. Shorten the clip. Trim the first and last second.
4. Try a video format if the service plays MP4 inline.

Our Discord video guide covers the video route, and compressing a screen recording is the better starting point if your GIF began as one.

Cut length first if you can, because it costs no quality at all. Every second you remove takes its frames with it. Then crop away empty margins, since pixels you do not show are pixels you do not store. Reduce width next, and frame rate last, because a low frame rate is the change viewers notice most.

ffmpeg -ss 1 -t 3 -i input.gif -vf "crop=480:270:80:45,fps=12,split[a][b];[a]palettegen[p];[b][p]paletteuse" trimmed.gif

That keeps three seconds starting at one second in, crops a 480 x 270 window offset 80 and 45 pixels from the top left, and runs at 12 fps. I did not benchmark this exact line, so measure it on your own clip. If the GIF is a UI demo, the crop is often the biggest win, since the toolbar and desktop never change.

They work, but you upload the file to someone’s server. For a meme, that is fine. For a screen recording of a client dashboard or private chat, it is not. A local ffmpeg run keeps the file on your Mac and has no daily limit.

For animated GIFs, Smol is the wrong tool. I ran Smol 1.0.35 on the test GIF with GIF as the output format. It wrote a file 3% smaller with the same 640 x 360 size and 60 frames. A second run with a 320 pixel width and quality 50 produced the same byte count, so the resize and quality settings did nothing to the animation. Use ffmpeg, or a GIF tool such as gifsicle, for this job.

Smol is built for still images, PDFs, video and audio. If your GIF started as a screen recording, compress the original video instead. It outputs MP4, MOV, WebM and MKV, with the resolution and audio options in the app. See the best video compressor for Mac, or Smol at $29 once.