GIF settings that keep the file small: fps and size

The surest way to make a GIF smaller is to cut the number of frames and the number of pixels in each frame. The frame count comes from the clip length and the frames per second (fps), and the pixel count comes from the width, so those are the three settings to adjust. This guide explains how the GIF format works and how each setting affects file size.

How the GIF format works

The GIF specification (GIF89a) stores colors in a color table, also called a palette. A color table’s size is a power of 2, up to 256 colors. There’s a global color table for the whole file, and each image (frame) can also carry its own local color table. That’s why GIF is often described as having up to 256 colors per frame. According to MDN, each pixel is an 8-bit value that points into the palette, and the image data is compressed losslessly with the LZW algorithm.

Animation works by showing a series of images in order. GIF has no “frames per second” value. Instead, each frame records how long to wait before moving on, in hundredths of a second. At 10fps, each frame is shown for 0.1 seconds. A GIF can’t hold sound.

What drives file size: clip length, fps and width

The frame count is the clip length in seconds multiplied by the fps.

Frames per second	5-second clip	10-second clip
5fps	25 frames	50 frames
10fps (default)	50 frames	100 frames
15fps	75 frames	150 frames

When you reduce the width, the height shrinks with it to keep the video’s aspect ratio. So the number of pixels per frame drops faster than the width does. For a 16:9 video:

Width	GIF resolution	Pixels per frame	vs. 480px
320px	320×180	57,600	about 0.44×
480px (default)	480×270	129,600	1×
640px	640×360	230,400	about 1.78×
800px	800×450	360,000	about 2.78×

Both tables are calculated from the settings. The actual size of a GIF depends on what’s in the video, so it won’t follow these ratios exactly. Still, more frames and more pixels mean a bigger file. If your GIF comes out too large, work through these in order:

• Clip: keep only the part you need. Halving the clip halves the frame count.
• fps: going from 10fps to 5fps halves the frame count. Motion looks less smooth.
• Width: going from 480px to 320px cuts the pixels per frame to about 0.44×.

Here are real results from synthetic test videos made with a test pattern (measured in desktop Chrome; results vary by device and browser).

Input	Settings	Result
1080p, 30-second MP4	0–10 s, 10fps, width 480px	480×270, 100 frames, 1.1 MB
640×360, 10-second WebM (829 KB)	Defaults (0–5 s, 10fps, width 480px)	480×270, 50 frames, 603 KB

In the second example, the original WebM was 829 KB for all 10 seconds, and a GIF of just 5 seconds of it came to 603 KB.

The 256-color palette and dithering

Video to GIF builds a single 256-color palette from frames sampled across the clip and uses it for every frame. Areas where colors change smoothly, like sky or gradients, have to fit into those 256 colors, so they can show banding (visible stripes).

Turning on Dithering mixes dots of different colors to make the bands less noticeable. It may increase file size, though, so it’s off by default. If size comes first, leave it off and turn it on only when the banding bothers you.

How to do it with ZEKILO Studio

1. Open Video to GIF and drag and drop one video, or pick it with [Choose files]. You can add MP4, MOV, WebM and MKV. A preview appears along with the length and resolution.
2. Set the Start and End of the Clip, choose Frames per second (5, 10 or 15fps) and Width (320, 480, 640 or 800px), then press [Start]. An estimate (resolution, frame count and approximate size) appears below the options. If it may go over 20MB, you’ll see “The GIF may exceed 20MB. Try lowering the fps or size.”
3. Check the size, resolution and frame count on the result card, then save the GIF with [Download].

By default, the clip runs from the beginning to 5 seconds, and it can be up to 30 seconds long. The estimated size is approximate and may differ from the actual size. Choosing a width larger than the video doesn’t enlarge it, so a 640×360 video set to 800px comes out at 640×360. Your file is processed in this browser and never leaves your device.

When a video works better than a GIF

A GIF can’t carry sound, and its size climbs quickly as the clip gets longer. Google’s web.dev gives an example where a 3.7 MB animated GIF became 551 KB as MP4 and 341 KB as WebM, and recommends replacing large GIFs with video.

If you need sound, a scene longer than 30 seconds, or accurate color, consider sending the video itself instead. Compress Video lowers the resolution and bitrate and saves the result as an MP4. For more on sending videos by email or in a chat app, see our guide on shrinking a video for email and messaging apps.

Summary

• GIF uses a color table of up to 256 colors per frame and lossless LZW compression. More frames and more pixels mean a larger file.
• Frame count = clip length × fps. A shorter clip or a lower fps means fewer frames.
• Going from 480px to 320px wide cuts the pixels per frame to about 0.44× (calculated for 16:9).
• Dithering reduces banding but may increase file size, so turn it on only when you need it.
• If you need sound or a long scene, sending a video may work better than a GIF.