What makes a GIF enormous
GIF has no motion compression. Every frame is stored more or less whole, so the file grows in a straight line with the number of frames — five seconds at 30fps is 150 full pictures. It is also limited to 256 colours per frame, which is why photographic footage comes out speckled.
The three dials that matter, in order of effect: dimensions (halving the width quarters the pixels), frame rate (10–15fps reads as smooth for most content), and length. A 480px, 12fps, three-second GIF is a different object from a 720p, 30fps, ten-second one — often twenty times smaller.
When not to use a GIF at all
For anything longer than a few seconds, or anything with real photographic detail, an MP4 is smaller by an order of magnitude and looks better. Every platform that accepts a GIF converts it to video behind the scenes anyway.
GIF still wins in three places: email, where video will not autoplay; documentation and READMEs, where a file that plays itself with no controls is the point; and anywhere the recipient will re-share it as an image.
Frames from a video
Given a clip, frames are sampled at the rate you choose rather than every frame being kept — which is what keeps the result usable. Trim the clip before converting if you only want part of it; trim video does that without re-encoding the whole thing.
Frequently asked questions
Why is my GIF so large?
GIF stores each frame almost in full — there is no compression across frames. Reduce the dimensions first, then the frame rate, then the length. Those three account for nearly all of it.
How many frames per second should I use?
Ten to fifteen looks smooth for screen recordings and simple motion. Thirty doubles the file for a difference most people will not see in a looping clip.
Why does my GIF look grainy?
GIF allows only 256 colours per frame. Photographs and gradients have to be approximated, which shows as speckling. Flat graphics and screen recordings survive far better.
Should I use a GIF or an MP4?
MP4 for anything more than a few seconds — far smaller, far better looking. GIF for email, README files, and anywhere it needs to play with no controls and be re-shared as an image.
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