What video formats can I convert to?

You can convert to MP4 and WebM, which are the most widely supported browser video formats. Input supports MP4, WebM, AVI, MOV, and MKV.

What is the difference between remuxing and re-encoding?

Remuxing rewraps the existing streams into a new container (e.g. MKV to MP4) without touching the video data — it is instant and lossless. Re-encoding decodes and re-compresses with a new codec or quality, which is slower and adds some generation loss.

Which output format is most compatible?

H.264 video in an MP4 container plays almost everywhere — phones, browsers, smart TVs and editors — making it the safest target. Reach for H.265, VP9 or AV1 only when a specific platform requires them or you need better compression.

Can I convert an iPhone MOV to MP4 without losing quality?

Often yes. iPhone MOV files usually already contain H.264 or H.265, so the tool can remux them straight into MP4 with no re-encoding and zero quality loss. A full transcode is only needed if you change the codec or resolution.

What is AV1 and should I use it?

AV1 is a royalty-free codec with better compression than H.265 and VP9, used by YouTube and Netflix. It is great for storage and bandwidth, but encoding is slow and playback needs a recent browser or device, so use it only when the target supports it.

Why does conversion take so long?

A re-encode runs every frame through FFmpeg in WebAssembly on your own device — nothing is uploaded — so the time scales with length, resolution and your CPU. Remuxing, by contrast, finishes almost instantly because no frames are re-compressed.

Will converting change the file size?

It can, a lot. A lower CRF or a more efficient codec like H.265/AV1 shrinks the file; switching to a less efficient codec or higher quality enlarges it. Remuxing leaves the size essentially unchanged since the streams are copied as-is.

Video Converter — Convert MP4, WebM Online Free

How to use Video Converter

The Video Converter re-encodes or remuxes MP4, MKV, WebM, MOV and AVI videos into your chosen output format using H.264, H.265, VP9 or AV1 codecs — entirely in your browser via FFmpeg WebAssembly with no server uploads. Convert a MOV from your iPhone for web playback, turn an AVI into a modern MP4, or prepare footage for a specific platform or editing application.

Click "Select Video" and open the source video file.
Choose the output container format (MP4, WebM, MKV or MOV).
Select the video codec (H.264 for compatibility, H.265 or VP9 for better compression, AV1 for cutting-edge efficiency).
Set the quality level (CRF) and optionally choose an audio codec and bit rate.
Click Convert and download the output video once processing completes.

Your data never leaves your device — 100% private processing.

Choosing a codec and container

The container (MP4, MKV, WebM) is the wrapper file format; the codec (H.264, H.265, VP9, AV1) defines how the video data is compressed. Not all codecs work in every container — MP4 works with H.264 and H.265 but not VP9; WebM works with VP8, VP9 and AV1. H.264 in an MP4 container is the safest choice for maximum compatibility across devices, browsers and platforms. H.265 halves the bitrate at the same quality but requires hardware decoding support. VP9 and AV1 are royalty-free alternatives used on YouTube and streaming services.

Codec and container compatibility
Codec	Container	Compatibility
H.264	MP4, MKV, MOV	Universal
H.265 (HEVC)	MP4, MKV	Modern devices / browsers
VP9	WebM, MKV	Chrome, Firefox, YouTube
AV1	WebM, MKV, MP4	Latest browsers, Android

Remuxing vs transcoding

Remuxing moves streams from one container to another without re-encoding — for example, changing an MKV with H.264 video into an MP4 with the same H.264 stream. It is instantaneous and lossless because no data is changed. Transcoding re-encodes the video with a new codec or quality setting and is much slower. If your source codec is already compatible with the target container, choose remux to save time and avoid quality loss. Transcoding is only necessary when changing codecs, resolution, quality or removing unsupported metadata.

Glossary

Container format: A file format (MP4, MKV, WebM) that packages one or more audio, video and subtitle streams into a single file.
Remux: Changing the container format of a media file without re-encoding the audio or video streams, preserving full quality.
Transcode: Decoding a media stream and re-encoding it with a different codec or settings, which is slower and introduces generation loss.
AV1: An open, royalty-free video codec developed by the Alliance for Open Media; offers better compression than VP9 and H.265.
VP9: An open-source video codec from Google used extensively on YouTube and in WebM containers; competitive with H.265 in compression efficiency.

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Video Converter

How to use Video Converter

Choosing a codec and container

Remuxing vs transcoding

Glossary

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Frequently Asked Questions

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