Media

MP4 test files, any size.

Set a size and generate a structurally valid MP4 immediately. Nothing is uploaded and nothing is stored.

0bytes
Exact size

MP4, built to spec.

Each file is an ISO Base Media container with correct ftyp branding. The size you ask for is reached with a free box, the container’s own reserved-space atom, so the result opens in container parsers and ffprobe — note it carries no video track, so it will not play. Most people generate these for testing upload size limits where playback is not required.

Questions.

How small can an MP4 file be?

About 48 bytes. Below that the format cannot carry its mandatory structure, let alone padding.

Will the file open normally?

Yes — it opens in container parsers and ffprobe — note it carries no video track, so it will not play, because the padding lives in a free box, the container’s own reserved-space atom.

Can I ask for an unusual size?

Any byte count above the minimum works, including values like 3,145,728 or 27.5 MB. Drag the caliper or type the number.

Noticed an issue with this test file? Report an issue →