Convert Video

Change a video's format or codec without uploading it.

Choose video file or drop it anywhere on this page MP4 · MOV · WEBM · MKV · AVI · WMV · FLV · M4V · 3GP · MPEG · +3 Processed on your device — never uploaded

This tool does its work with JavaScript in your own browser — that is exactly why your files never get uploaded. Please enable JavaScript to use it.

Settings

Output format

Video codec

Resolution

Bitrate

Audio codec

How to convert video

Drop a video in. AVI, MKV, MOV, MP4, WebM and WMV are all accepted.
Pick the output format and codec. MP4 with H.264 plays on every device.
Convert and download.

About this tool

Video format problems are mostly container problems rather than codec problems. MP4 and MKV are containers — they hold a video track, an audio track, and metadata. The codec is what actually compressed those tracks. A video "in MKV format" might contain H.264 video and AAC audio, and converting it to MP4 with the same codecs could just be a remux with no quality loss at all — the tool tries stream copy first when the target codec matches the source.

The situations that genuinely require re-encoding are changing the codec (from H.264 to AV1, for example) or changing the container to one that the existing codec does not fit into (WebM only accepts VP8, VP9 or AV1 video and Vorbis or Opus audio). In those cases every frame goes through decode and encode, and the tool makes the cost visible with a progress indicator.

Questions

Which format should I choose?

MP4 with H.264 is the safe choice for maximum compatibility — it plays on every phone, TV, browser and desktop player. WebM with VP9 is the right choice for web embeds where you want smaller files and do not need legacy support. MOV is required by some Apple workflows. AV1 in MP4 or WebM gives the best compression but is slower to encode and does not play in very old software.

Can I convert without losing quality?

Changing codec always involves re-encoding from the decoded frames, which means some quality loss for lossy codecs. To minimise it, choose a low CRF value or a high bitrate. If you are converting to the same codec at the same settings, the quality will be nearly identical to the source. Converting between two lossy formats introduces generation loss — each re-encode compounds any existing artefacts.

Why is WMV listed as input but not output?

Windows Media Video decodes fine via ffmpeg.wasm. Encoding WMV requires a proprietary codec that is not part of open-source ffmpeg builds. Almost nothing needs a WMV output in 2026; convert to MP4 instead.

What about AVI files?

AVI is a container from the 1990s that is still surprisingly common from old cameras and digitised VHS tapes. It decodes reliably; converting to MP4 with H.264 is the most sensible path for files you want to play on modern devices.

Convert Video

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About this tool

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