People often say a GIF must be larger than an MP4. But the answer depends on which seconds, dimensions, and frame rate are compared. A smaller GIF does not necessarily preserve the same visible detail.
We created one reproducible three-second synthetic MP4 and converted its entire duration with the same FFmpeg WebAssembly engine used by Toolit. This controlled case shows how settings change bytes; it is not an average for real-world footage.
The practical answer
At 320px and 8fps it measured 196.3KiB, about 32% of the 620.6KiB test MP4, after discarding pixels and frames.
At 480px and 20fps it measured 870.6KiB, about 1.40 times the MP4 size.
Use GIF for a brief silent loop; keep MP4 when sound, longer playback, or controls matter.
One three-second range, three GIF presets
- 1
We generated a 640×360, 24fps, three-second synthetic pattern as H.264 MP4 using Toolit's bundled FFmpeg WebAssembly build. The source measured 635,447 bytes (620.6KiB). Synthetic input makes the exact scene reproducible.
- 2
We converted the same full 0–3 second selection with Compact (maximum 320px, 8fps), Balanced (480px, 12fps), and Smooth (480px, 20fps). The tool's actual palette-generation and GIF-encoding arguments were used.
- 3
We measured output bytes and used 1KiB=1,024 bytes. The reproducible script is scripts/measure-gif-presets.mjs in the repository. The MP4 used a fast ultrafast encoding preset, not maximum compression, so a typical well-compressed MP4 could be smaller. Results apply only to this scene and settings.
Measured outputs
Compact produced fewer bytes than the source; Smooth produced more. This does not prove GIF compresses better than MP4. We greatly reduced the GIF's dimensions and number of saved frames.
| File | Settings | Measured size | Relative to MP4 |
|---|---|---|---|
| Source MP4 | 640×360 · 24fps · 3 sec | 620.6KiB | Baseline |
| Compact GIF | Up to 320px · 8fps | 196.3KiB | 0.32× |
| Balanced GIF | Up to 480px · 12fps | 567.3KiB | 0.91× |
| Smooth GIF | Up to 480px · 20fps | 870.6KiB | 1.40× |
Why did size change so much?
GIF stores each frame using a limited color palette; complex video can show rougher gradients. MP4 is designed to encode a sequence of video frames efficiently. At comparable dimensions and visible detail, MP4 often has the advantage. In this test, reducing GIF pixels and frames enough reversed a simple byte comparison.
Three seconds at 8fps contains about 24 sampled frames; at 20fps it contains about 60. Raising the frame edge from 320px to 480px also adds pixels per image. Real size is not perfectly proportional because scene colors and motion affect compression.
Choose for the job, not just the smallest number
A small looping GIF is convenient for demonstrating a button click in chat or documentation. GIF has no audio, so use MP4 for speech or a longer explanation. Inspect small text and colors at the actual display size before accepting a tiny GIF.
| Use case | Try first | Check |
|---|---|---|
| Short silent loop | GIF | Legibility, motion, upload cap |
| Sound or long playback | MP4 | Playback and codec support |
| Strict file limit | Test both | Compare the same necessary range |
What the test does not establish
One synthetic pattern cannot represent faces, games, screen recordings, or dark footage. Nor was the MP4 created for best possible compression. These measurements cannot establish that GIF is generally smaller or always a fixed multiple larger.
For your own file, compare the same useful section in both formats and inspect size, appearance, and playback in the destination. No GIF preset guarantees a target number of megabytes.
Official documentation used for this analysis
Match settings before judging GIF versus MP4 size
Here the 320px·8fps GIF was smaller than its MP4 source while the 480px·20fps GIF was larger. Duration, dimensions, and frame rate explain more than a blanket claim that GIF is always larger.
Try GIF for a short silent loop. Keep MP4 for sound, length, or video clarity, and decide against a real upload limit using the output you actually measured.