Video files come in different containers — MP4, MOV, MKV, AVI, WebM — and not every device or platform accepts all of them. Let's look at how they differ and which to choose.
MP4 — the universal format
MP4 with H.264/AAC codecs is the most widely compatible option: every social network, messaging app, smartphone, and player accepts it. Without any specific requirements, MP4 is the right default choice for sending or publishing video.
MOV — Apple's format
MOV was developed by Apple and is the default on iPhone, iPad, and in Final Cut Pro. It works great within the Apple ecosystem, but not every platform or device elsewhere accepts it directly — you often need to convert it to MP4 before uploading.
MKV — a flexible container
MKV (Matroska) is an open format that can hold several video and audio tracks, subtitles, and chapters in a single file. It's popular for movies and shows with multiple audio tracks, but it isn't supported by every player and is almost never accepted by social networks.
AVI — an older format
AVI is one of the oldest video formats, still found in archives and on older hardware. It's less efficient at compression than modern formats and doesn't support many features, like embedded subtitle tracks.
WebM — built for the web
WebM (VP9/Opus) is an open format optimized for playing video directly in a browser. It delivers good quality at a small file size and is commonly used on websites, but it's less universal for sending through messaging apps.
How to choose a format
- Sending via a messaging app or uploading to a social network — MP4.
- A video from an iPhone needs to open on a non-Apple device — convert it to MP4.
- A movie with multiple audio tracks and subtitles — MKV.
- Video meant to be embedded on a website — WebM.
How to convert a video to the format you need
The video converter translates clips between MP4, MOV, MKV, AVI, and WebM in any direction, and it also accepts FLV, WMV, 3GP, and TS on input. Upload the file, choose the output format, and download the result — processing happens on the server via ffmpeg, and the file is deleted right after conversion. The maximum source file size is 50 MB; the tool is built for short clips.
If what you need isn't a different format but a smaller file, that's a separate task — changing the video resolution, not the container.
Bottom line
MP4 is the universal choice for most situations, MOV mainly matters within the Apple ecosystem, MKV is for complex files with multiple tracks, and WebM is for the web. Converting a clip between formats can be done online in one step.