How a video becomes a GIF
A GIF is a stack of still pictures shown one after another, like a flip book. To make one from a video, the tool:
- Grabs frames from the part you selected at the frame rate you chose (12 fps means one picture every 1/12 of a second).
- Scales each frame to the width you picked.
- Reduces the colours. A GIF frame can only use 256 colours, while a video frame can have millions. The tool picks the best 256 with a method called median cut and, if dithering is on, mixes neighbouring dots to fake the missing shades.
- Compresses each frame with LZW, the lossless method built into the GIF format, and writes the delay for each frame.
All of this runs in your browser. The video is decoded by its built-in WebCodecs engine and nothing is uploaded.
Why GIFs get big, and how to keep them small
A GIF stores every frame as a full picture with limited compression, so its size grows with every setting you raise:
| Setting | Frames | Pixels per frame | Relative work |
|---|---|---|---|
| 3 s, 480 × 270, 10 fps | 30 | 129,600 | 1× |
| 3 s, 480 × 270, 20 fps | 60 | 129,600 | 2× |
| 3 s, 800 × 450, 10 fps | 30 | 360,000 | 2.8× |
| 6 s, 800 × 450, 20 fps | 120 | 360,000 | 11× |
The last row has eleven times as much picture data as the first. File size does not scale exactly with it, because static areas compress well, but the trend holds. The best levers, in order: shorter clip, smaller width, lower frame rate.
Worked example
You want a reaction GIF from a 1080p phone video, from 0:12.0 to 0:15.0.
- Length: 3 seconds. At 12 fps that is 36 frames.
- Width 480 px keeps the 16:9 shape: 480 × 270.
- Each frame is 129,600 pixels, about 0.5 MB of raw colour data while it is being processed.
- With One palette, pixels that do not change between frames are marked transparent, so a mostly still background costs almost nothing after the first frame.
If the result is still too big for where you want to post it, drop to 320 px or 8–10 fps before cutting the length.
Colour options explained
- One palette (smaller file): the whole animation shares one set of 256 colours. Unchanged pixels are skipped from frame to frame. Best for screen recordings, cartoons and most clips.
- Palette per frame (best colour): every frame gets its own 256 colours. Colours look better when the scene changes a lot, but files are bigger.
- Dithering: smooths skies and skin tones by mixing dots. Turn it off for flat graphics and screen recordings, where it only adds noise and size.
GIF or animated WebP?
Animated WebP stores every frame with modern compression and full colour, so it is usually much smaller than a GIF and looks better. All current browsers show it, as do many chat apps. Choose GIF when you need it to work everywhere, including old email clients and forums. Creating WebP needs a browser that can encode WebP images, such as Chrome, Edge or Firefox; Safari users can still make GIFs.
Tips
- Cut first for long videos. Finding three seconds in an hour-long file is easier after a rough cut with Trim Video.
- Record something to loop. Use the Screen Recorder to capture a quick demo, then turn the best moment into a GIF.
- Long clips belong in MP4. For anything over about 15 seconds, a short video from the Video Compressor is often ten times smaller and looks better.
- Shrink still images such as thumbnails with Compress Image.
- Frame timing: GIF delays are stored in hundredths of a second, so 12 fps is saved as a mix of 8- and 9-hundredth delays that add up to the right length.