How it works
Why are GIFs so big? (And how to make them smaller)
A three-second GIF can be bigger than a minute of video. That's not a bug in your file. It's how the format works, and once you know why, you know what to cut.
GIF is a 1987 image format doing a video's job
GIF was designed for still images on slow dial-up connections. Animation was bolted on as a sequence of images. Modern video formats are built around one idea GIF mostly lacks: only store what changes between frames.
A video codec stores a full frame now and then, and for the rest stores the differences and motion. A GIF stores each frame as a picture of its own. GIF can reuse the unchanged parts of the previous frame, but it has nothing like a video codec's motion prediction. So a GIF of someone waving stores something close to the whole scene, over and over.
The four things that decide a GIF's size
| Factor | Effect on size | What to do |
|---|---|---|
| Dimensions | Biggest. Double the width and height, roughly 4× the size. | Resize to the size it'll actually be shown. |
| Frame count | Roughly linear. Twice the frames, about twice the size. | Lower the fps and trim the length. |
| Colours | Up to 256 per frame. Fewer colours compress better. | Reduce the palette, especially on flat graphics. |
| Noise and dithering | Grainy footage and dither patterns break up GIF's compression. | Use lossy compression; avoid heavy dithering. |
Why dimensions matter most
Size grows with area, not width. A 960×540 GIF has four times the pixels of a 480×270 one. If it's going to be shown at 480 px, half the file is pixels nobody sees.
Why photos make huge GIFs
GIF uses LZW compression, which works by finding repeated runs of the same colour. A cartoon with big flat areas compresses beautifully. Camera footage has subtle noise in every pixel, so there are hardly any runs to find. That's why a screen recording of an app is small and a clip of a film is enormous.
What "lossy GIF" means
GIF itself is lossless. Lossy GIF tools cheat a little: they nudge pixels to nearby colours so LZW finds longer runs. You lose a bit of detail and the file shrinks, often by a third or more.
Gifpresso takes a different route. It works on the levers above: frame rate, colours and, when it has to, dimensions. It searches for the best mix that fits your target size, and the darker the roast, the harder it pushes.
When to stop using a GIF
If it's longer than about 10 seconds or it's real-world footage, an MP4 or WebM will usually be 5–10× smaller at better quality. Many sites already convert GIFs to video behind the scenes. GIF still wins where video isn't supported: email, emoji, stickers, and some chat apps and docs.
FAQ
Is WebP or APNG better than GIF?
Both support more colours and compress better, and browsers support them well. But emoji slots, email clients and many tools still expect GIF, which is why it's still everywhere.
Why did my GIF get bigger after editing?
Re-saving often adds dithering or a fuller palette. Both make LZW less effective. Compress again with fewer colours.
What's the best fps for a GIF?
For most uses, 10–15 fps. Below 10 starts to look choppy; above 20 rarely looks better at GIF sizes.