WebM to MP4 Converter - Convert WebM to MP4 Online Free

How to convert WEBM to MP4

Add your WebM videos. Drop up to 20 WebM files into the box, or browse for them. Each one can be up to 200 MB.
Pick a preset. Match source keeps the quality and size, Web 720p and Small file shrink the MP4 for sharing in chats.
Trim or resize if you like. Play the video and press Start here and End here to keep only a part, or pick a resolution such as 720p.
Convert and download. Press Convert. One or two files download directly, more than two come as a ZIP with a README.

Want the WebM back later for your website? MP4 to WebM goes the other way.

Why convert WebM to MP4?

WebM is the open video format of the web.

Chrome, Firefox and screen recorders love it, and so do sites like YouTube behind the scenes.

Outside the browser it is a different story. iPhones, WhatsApp, Instagram, PowerPoint, Premiere and many smart TVs refuse a WebM, but all of them take an H.264 MP4.

Converting swaps the codecs, not just the file extension. Renaming .webm to .mp4 does not work - the video inside is still VP9.

WebM vs MP4

	WebM	MP4
Made by	Google (open, royalty-free)	MPEG (ISO standard)
Video codecs	VP8, VP9, AV1	H.264 (or HEVC, AV1)
Sound codecs	Opus, Vorbis	AAC
Plays on	Chrome, Firefox, Edge, Android, VLC	Everything, including iPhone, Windows and TVs
Transparency	Yes (VP8/VP9 alpha)	No
Best for	Websites, screen recordings	Sharing, editing, social media

Short clip for a chat? A GIF may be all you need - try Video to GIF.

What happens to the codecs

The video (VP8, VP9 or AV1) is re-encoded to H.264 at high quality - CRF 20 with Match source, which is visually lossless.

The sound (Opus or Vorbis) becomes AAC, the audio format every phone and editor understands. The MP4 gets fast start, so it begins playing before it has fully loaded.

Web 720p - the usual choice for websites, email and chats.
Small file - 480p, for messengers with size limits.
High quality - CRF 18, for editing or archiving.

Tips

Screen recording too big? Recorders often save huge WebMs. Web 720p usually makes them several times smaller.
Odd size like 1366 x 767? H.264 needs even dimensions, so the size is nudged by a single pixel where needed.
Transparent WebM? MP4 cannot store transparency, so see-through areas come out as a solid background.
Only want the audio? Video to MP3 pulls the sound out of a WebM too.

Your video is converted on our server with FFmpeg. The upload is deleted right after converting and the MP4 once you download it.

Frequently Asked Questions

Drop your WebM into the box, keep the Match source preset and press Convert.

One or two files download directly, more than two come as a ZIP.

iPhones and WhatsApp expect H.264 video with AAC sound in an MP4. WebM uses VP8, VP9 or AV1 with Opus or Vorbis, which many apps simply do not support. Converting fixes that.

No. The extension changes, but the video inside is still VP9 or VP8, so most players still refuse it. The codecs have to be converted, which is what this page does.

The video is re-encoded, but with Match source it uses CRF 20, which looks the same as the original to the eye. Pick High quality if you plan to edit it further.

Yes. VP8, VP9 and AV1 WebMs are all converted to H.264, the most compatible video codec there is.

MP4 has no alpha channel, so transparent parts of a WebM become a solid background. Keep the WebM for websites that need the see-through effect.

Up to 200 MB per video and 20 videos per batch. For long recordings, trim the part you need or pick 720p.

Yes, it is free with no account. Your video travels to our server over HTTPS, is deleted as soon as the MP4 is made, and the MP4 is deleted once you download it.