Containers and codecs are different things
MP4, MOV, MKV, AVI and WebM are containers: boxes that hold video and audio streams. The codec inside — H.264, VP9, AV1, AAC — determines quality and size. That is why two MP4 files of the same length can differ tenfold in weight, and why changing container alone sometimes takes seconds while a real transcode takes minutes.
MP4 with H.264 is the answer whenever compatibility matters. WebM is the answer when you self-host and want royalty-free efficiency. MKV is for libraries that need multiple audio tracks and subtitles.
Expect conversion to take real time
A transcode has to decode and re-encode every frame. On a modern laptop that runs at a decent multiple of playback speed; on a phone it can be slower than real time. Convert the shortest clip that serves your purpose, and prefer a desktop for anything over a few minutes.
Supported video converter formats
- MP4
- WEBM
- MOV
- AVI
- MKV
Frequently asked questions
What is the best format to upload to social media?
- MP4 with H.264 video and AAC audio. Every platform accepts it and re-encodes from it cleanly.
Why is my GIF bigger than the video?
- GIF has no modern compression and stores every frame at 256 colours. Keep GIF exports short and small, or use WebM for anything longer than a few seconds.
Is there a length limit?
- Only the 100 MB file size cap; available browser memory becomes the practical limit before that.