WebM to MP4 Converter
WebM is what browsers record and stream; MP4 is what editors, phones and messaging apps expect. This page converts the first into the second, with a fixed 30 fps so screen recordings drop cleanly onto an editing timeline.
Video Converter
or drop MP4, MOV, MKV … files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
Lower is better quality and a bigger file. 18 looks identical to the source, 23 is the default, 28 and above shows visible softening.
Frames per second. Keep the source rate unless a platform asks for a specific one; 15–20 fps is plenty for GIFs.
Only used for PowerPoint files and single still images: how long each slide or picture stays on screen.
Auto uses AAC for MP4/MOV and Opus for WebM. Copy keeps the original sound untouched when the new format supports it.
192 kbps is transparent for music; 128 kbps is enough for speech.
Width of the animation in pixels; height follows the aspect ratio. 480 px suits chats, 720 px or more gives a high-quality GIF but a much larger file.
GIF holds at most 256 colors. Fewer colors make a smaller file but cause banding on gradients and skin tones.
Mixes palette colors in a fine pattern to hide banding. Sierra gives the smoothest result; none gives the smallest file.
Whether the animation repeats endlessly or plays one time and stops.
Optional. Seconds (e.g. 75) or minutes:seconds (1:15). Leave empty to start at the beginning.
Optional. Same format as the start time. Leave empty to keep everything up to the end.
The converted file will be at or just under this size.
How to use this tool
- 1
Choose your WebM files
Add up to 20 recordings or downloaded clips, 95 MB maximum per file.
- 2
Review the frame rate
Frame rate is preset to 30 fps to steady variable-rate browser captures. Switch it to Same as source for film-style footage, and use Advanced settings for trimming or a size limit.
- 3
Convert and download
Press Convert to MP4. Files are deleted from our servers 30 minutes after processing.
If a WebM will not import into your editor, will not send in a chat app or shows no length in the player, converting it to MP4 with H.264 and AAC solves all three at once.
Where WebM files come from
Google announced WebM in 2010 as a royalty-free format for HTML5 video, pairing the VP8 codec it had acquired from On2 with Vorbis audio. VP9, AV1 and Opus were added later. Because Chrome and Firefox can encode it without paying patent fees, it became the default output of the MediaRecorder API, which is what most browser-based screen recorders, meeting tools and webcam testers use under the hood.
That makes WebM common in exactly the places where people need to share the result: a bug report recorded in the browser, a lecture capture, a clip saved from a web page. The receiving end, whether an editor, a phone gallery or a messaging app, was built for MP4.
- WebM announced by Google
- 2010
- Video codecs a WebM can hold
- VP8 · VP9 · AV1
- Audio codecs a WebM can hold
- Vorbis · Opus
- First Safari for Mac to play WebM
- 14.1
WebM problems this conversion fixes
The editor greys out the file
iMovie, Final Cut Pro and many Windows editors have no WebM importer. The MP4 imports directly.
The player shows no duration and cannot seek
Browser recordings often lack an index. The converted MP4 is written with a full one.
Audio and video drift apart in the edit
MediaRecorder captures at a variable frame rate. The 30 fps preset turns it into a constant rate editors handle.
A chat or social app rejects the upload
Instagram, WhatsApp and most social apps document MP4 as their video format. H.264 + AAC passes their checks.
WEBM
WebM video
WebM is an open, royalty-free video format released by Google in 2010 for the web. It is based on Matroska and holds VP8, VP9 or AV1 video with Vorbis or Opus audio, and VP9 WebM can include an alpha channel for transparent video. Browsers play it natively, and browser screen recorders often produce it. Apple devices, video editors and social platforms have historically had weaker support than for MP4.
- Compression
- Lossy
- Transparency
- Yes
- Animation
- –
- Introduced
- 2010 · Google
MP4
MPEG-4 video
MP4 (MPEG-4 Part 14) is a multimedia container standardised by ISO/MPEG and based on Apple's QuickTime format. It usually holds H.264 or HEVC video with AAC audio, and can also carry subtitles, chapters and metadata. It is the most compatible video format in the world, playing on phones, browsers, TVs, game consoles and social platforms. The video inside is almost always lossy, so repeated re-encoding gradually reduces quality.
- Compression
- Lossy
- Transparency
- –
- Animation
- –
- Introduced
- 2001 · Moving Picture Experts Group (MPEG)
WebM files usually come from a browser, either a screen capture or a saved web video, and people convert them to MP4 to edit, post or send them somewhere that does not read VP9 or Opus.
Will the MP4 be larger than the WebM?
Often a little, because H.264 needs more bits than VP9 for the same detail. Screen recordings of slides and code shrink well under any codec, so the difference there is small. For camera footage, expect the MP4 to be somewhat bigger at the default Quality (CRF) of 23.
When the file has to stay under a cap, turn on Limit file size and enter the number; Discord's free tier, for example, allows 10 MB per upload. You can also set Resolution to 720p for a talking-head recording, which rarely needs more. Our guide to compressing video for Discord and email lists the common limits. If you need the opposite direction for a website, MP4 to WebM explains when the smaller file is worth it.
WebM to MP4 FAQ
Why can't I scrub through my WebM screen recording?
Recordings made with the browser's MediaRecorder API are written as a live stream, so the file often has no duration and no seek index. Players then show 0:00 or jump to the start. The MP4 written here has a complete index, so the timeline works.
Does Safari play WebM now?
Safari 14.1 on macOS Big Sur was the first version to play WebM, in 2021. Older Macs, many iPhone apps, iMovie and Final Cut Pro still do not import it, which is why MP4 remains the safer file to send.
Will the Opus audio in my WebM play after conversion?
The MP4 gets AAC audio by default, which every phone and editor decodes. Keeping Opus inside MP4 is possible under Audio codec, but older players stay silent with it, so leave the default unless you know the target.
Why did my transparent WebM get a black background?
VP8 and VP9 WebM files can carry an alpha channel; H.264 MP4 cannot. The transparent areas are flattened. Keep the WebM for web overlays and stickers, and use the MP4 copy only where transparency does not matter.
Is WebM lower quality than MP4?
No. Quality depends on codec and bitrate, not the container. VP9 in WebM is roughly as efficient as HEVC. The conversion re-encodes to H.264 at Quality (CRF) 23, which looks the same at normal size but makes a somewhat larger file.
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- MKV to MP4 ConverterConvert MKV to MP4 free online. Turns OBS recordings and Matroska files into H.264/AAC MP4 that iMovie, iPhones and smart TVs open. Up to 20 files.
- OGV to MP4 ConverterConvert OGV files with Theora video and Vorbis audio into H.264 MP4 that plays on iPhone and Safari and imports into Premiere Pro or iMovie. No account.
- GIF to MP4 ConverterConvert GIF to MP4 video online. Animated GIFs become H.264 clips that are typically a fraction of the size and play smoothly in chats and on social media.
- AV1 to MP4 ConverterConvert AV1 video to an H.264 MP4 that plays on older laptops, phones, TVs and editors without AV1 decoding. Works for AV1 in MP4, WebM, MKV or IVF.