Convert WebM to MP4

Turn a WebM clip into an MP4 that opens on iPhone, Windows and Telegram. VP9 and Opus become H.264 and AAC in your browser.

Drop your files here

.webm · up to 200 MB

Choose files

High qualityBalancedSmall file

More settings

ResolutionFrame rateAudio bitrate

How to Convert to MP4

1
Add your WebM file
Any .webm clip, up to 200 MB and 5 minutes long. Screen recordings and browser-captured video are the usual source.
2
Pick a quality preset
High keeps the most detail, Small gives the lightest file. Resolution and frame rate can be trimmed too.
3
Click Convert and download the MP4
The result plays in Safari, QuickTime, Windows and every messaging app, with nothing WebM-specific left behind.

Why WebM can't just be renamed to .mp4

WebM carries video encoded as VP8, VP9 or AV1, and none of those codecs is something MP4 players are required to support. Some software will technically accept VP9 wrapped in an .mp4 file, but Safari, QuickTime, most smart TVs and most messaging apps will not. Renaming a file only changes what the extension claims, not what's inside it. Opening everywhere means decoding the original video and re-encoding it as H.264, the codec virtually every player already understands, and that is what this converter does.

What happens to transparency and to the audio track

H.264 has no concept of a transparent pixel, so a WebM with an alpha channel, common in VP8 or VP9 screen captures with a see-through background, turns that area opaque black in the MP4. If the transparency has to survive, Video to GIF and Video to WebP both preserve alpha. Audio is simpler: Opus and Vorbis, WebM's usual codecs, both convert cleanly to AAC, since Safari and many hardware players can't decode Opus at all. A WebM with no audio track converts fine too; the MP4 comes out silent, with no error.

Converted from WebM on your device

The WebM picture is decoded and encoded again as H.264 by your browser's own encoder, with the sound turned into AAC, all inside this tab, so a screen recording never travels to a server. There is no account and no queue, and closing the tab clears everything the moment you're done.

Frequently asked questions

Why can't WebM just be renamed to .mp4?

Renaming only changes the file extension, not what's inside. WebM holds VP8, VP9 or AV1 video, and most MP4 players, Safari and QuickTime included, expect H.264 and won't open the file no matter what it's called.

Why isn't there an instant, no-re-encode mode?

That's only possible when the codec inside can be copied as-is into the new container, and VP8/VP9/AV1 can't be, because no combination of players would reliably open the result. Every conversion here re-encodes the video to H.264.

What happens to transparent areas in my WebM?

H.264 doesn't support transparency at all, so any transparent pixels turn solid black in the MP4. If you need to keep them, Video to GIF or Video to WebP both preserve an alpha channel.

Why does the audio change from Opus to AAC?

WebM normally carries Opus or Vorbis audio, and Safari and a lot of hardware players and TVs can't decode either one. AAC is the format virtually everything expects, so the audio is always re-encoded to it.

Will the MP4 be bigger than the original WebM?

Often somewhat, yes. VP9 tends to compress more efficiently than H.264 at the same visual quality. Picking the High quality preset favors detail, while Small trades some sharpness for a lighter file.

Which quality setting should I pick?

Balanced is a safe default for most clips. Choose High for footage with fine detail or fast motion you want to keep sharp, and Small when file size matters more than every last pixel.

What's the maximum file size and length?

Up to 200 MB and 5 minutes, since every frame is decoded and re-encoded in the browser. Longer or larger recordings convert best after trimming them down first.