Rescreen / Free tools / MOV to WebM

MOV to WebM converter

Drop a MOV here for a VP9 and Opus WebM, re-encoded in your browser with little visible loss.

Drop a MOV file here

or choose one from your device

Up to 2.0 GB. Stays on your device.

How to convert MOV to WebM

Three steps, all on this page.

Choose your MOV
Choose or drop a MOV file. The page reads what is inside and checks that this browser can convert it before anything starts.
Convert to WebM
Pick the options you want, then press Convert to WebM. Tracks that a WebM can hold as they are get copied, which is near instant.
Check and download
The new file is opened again and checked against the original before it is offered. Play it in the preview, then download it.

What changes from MOV to WebM

MOV is Apple’s QuickTime format. MDN lists it as playable only in older versions of Safari and browsers that had Apple’s QuickTime plugin, while WebM and MP4 play in all browsers. Source
A Mac saves a screen recording as a MOV, named “Screen Recording [date] at [time].mov” when it saves automatically. Source
On macOS Tahoe 26 and later, screen recordings are HEVC when the Screenshot app’s Capture Format is HDR, and H.264 otherwise. An iPhone on High Efficiency records HEVC. Source
VP9 is one of the two video codecs WebM requires, and plays in all current Chrome, Edge, Firefox, Opera and Safari. It can carry an alpha channel, but Safari does not show VP9 transparency. Source
Opus is the open audio codec WebM uses for speech and music alike, from 6 to 510 kbps. Source
Apple added an alpha channel to HEVC so video can be composited over other backgrounds in apps and on the web. Safari plays it; it is Apple’s answer to transparent video, where other browsers use VP9. Source
HandBrake writes WebM with VP8, VP9 or AV1 video and Vorbis or Opus sound. Source

MOV file

MOV (QuickTime)

PictureH.264, HEVC or ProRes
SoundAAC or PCM

WebM file

WebM

PictureVP9
SoundOpus

Who converts MOV to WebM

Mostly web developers and designers with a Mac. A screen recording made with Shift-Command-5 or QuickTime Player is saved as a MOV, and a MOV is the one format a web page cannot rely on: outside Safari, browsers do not promise to play it. So the demo for a landing page, the clip in the docs or the walkthrough in a pull request has to become WebM, MP4 or both. Others come with a MOV that has a transparent background, an animated logo or a lower third from After Effects or Motion, and want it to play over a page.

What happens to a MOV on the way to WebM

A Mac or iPhone MOV holds H.264 or HEVC video with AAC sound. WebM accepts none of the three, so this is never a quick copy like MOV to MP4: the picture is decoded and encoded again as VP9, and the sound as Opus. The result is a little softer than the original in the places a re-encode always shows first, small text and fast movement, and usually looks the same at normal size.

HEVC needs a browser that can decode it. Safari on a Mac and Chrome or Edge on most computers can; Firefox cannot, and the page says so before you pick a file. Two kinds of MOV are turned away with a message saying what to do: ProRes, which editors export and no browser decodes, and a video whose sound is Apple Lossless.

VP9 WebM or H.264 MP4 for the web

For a page that has to work everywhere, an H.264 MP4 is still the safe single file. WebM is worth adding when you want an open format, when a platform asks for it, or when you need transparency in Chrome and Firefox. Size is not a reason on its own: a browser’s VP9 encoder works fast, not hard, so a screen recording can come out about the same size as the MP4 or larger. ffmpeg, given time, made the same recording well under half the size.

We converted a 43-second 1080p screen recording with narration, saved as a MOV by Apple’s own encoder, in three browsers on an M1 Mac. Chrome and Safari’s engine each took about five seconds. Firefox took a minute, and its WebM came out smallest. Copied into an MP4 instead, the H.264 recording took a fraction of a second and stayed 4.5 MB.

MOV	Size	Chrome	Safari	Firefox	ffmpeg
H.264	4.5 MB	4.7 MB in 5 s	6.1 MB in 5 s	2.5 MB in 1:00	1.7 MB in 33 s
HEVC	5.7 MB	4.7 MB in 5 s	6.3 MB in 5 s	cannot decode HEVC	1.7 MB in 35 s

A 43-second 1920×1080, 30 fps screen recording with 128 kbps AAC narration, encoded as a MOV with Apple’s VideoToolbox encoder, converted on this page at the default quality on an M1 Mac (macOS 15.8). Chrome 155, Firefox 157 and Safari’s engine as Playwright builds it (WebKit 27.2). ffmpeg 9.0 used libvpx-vp9 at CRF 31.

Where each one plays

What matters for a web page is which browsers play the file and whether it can be see-through. This is how the formats in question compare, from MDN’s codec guides and Apple’s documentation.

Format	Plays in	Transparency
H.264 in an MP4	Every major browser	No
VP9 in a WebM	Chrome, Edge, Firefox, Opera, Safari	Yes, except in Safari
HEVC in a MOV or MP4	Safari; Chrome and Edge where the computer has HEVC support	Yes, in Safari
Any MOV	Not promised in any browser but Safari	Depends on the codec

Playback in current desktop and mobile browsers, from the sources listed under “Format facts” below.

Markup for a web page: WebM first, MP4 second

Give the browser a list and it plays the first file it can. Put the WebM first and the MP4 second, each with its type, so a browser skips a format it cannot play without downloading it. For a silent demo that loops like a GIF, keep muted and playsinline, or phones will not start it on their own. Without the loop, swap autoplay loop for controls.

<video autoplay muted loop playsinline width="1280" height="720">
  <source src="demo.webm" type="video/webm">
  <source src="demo.mp4" type="video/mp4">
</video>

Transparent MOVs

This converter does not keep transparency. An HEVC video with alpha converts, but the WebM comes out with a solid background where the MOV was see-through. ProRes 4444, the usual way an editor hands over a transparent clip, is refused outright because no browser decodes ProRes.

For a transparent WebM, use ffmpeg with a ProRes 4444 export, as shown under “Other ways” below, and keep -pix_fmt yuva420p, which carries the alpha channel into the VP9. Safari will still show that WebM with a solid background, so for Safari also export an HEVC-with-alpha MOV from Motion, Final Cut Pro or Compressor and list it first in the <video> element with type='video/mp4; codecs="hvc1"'.

When not to convert

Skip it if the page only needs one file. An H.264 MP4 plays everywhere a WebM does, and the MOV to MP4 converter copies a Mac screen recording into one without re-encoding, with nothing lost. Skip it to save space, too: the table above shows a browser can make a WebM larger than the MOV. To shrink a recording, use the video compressor.

Converting will not add what the MOV does not have. A recording without system sound stays silent in the WebM; the guide to recording a Mac screen with computer audio explains why macOS leaves it out. A blurry or low-resolution recording stays that way, and a transparent background cannot be kept here.

If you are sending the video to a person rather than putting it on a page, keep MOV or use MP4. Email, chat apps, YouTube and editing apps take both, and a re-encode only costs quality.

Other ways to convert MOV to WebM

ffmpeg Mac, Windows or Linux, from the command line

Install ffmpeg (on a Mac with Homebrew: brew install ffmpeg).
For an ordinary MOV, run ffmpeg -i input.mov -c:v libvpx-vp9 -crf 31 -b:v 0 -row-mt 1 -c:a libopus -b:a 128k output.webm.
For a transparent ProRes 4444 MOV, add -pix_fmt yuva420p after libvpx-vp9, and use -an instead of the Opus settings if it has no sound.

The smallest files and the only free way to keep transparency, but slow: our 43-second recording took over half a minute on an M1 Mac.

HandBrake Mac, Windows or Linux

Open the MOV in HandBrake with Open Source.
On the Summary tab, choose WebM under Format.
Choose VP9 on the Video tab and Opus on the Audio tab, then press Start Encode.

Free, with presets and a queue for a folder of recordings. It does not keep transparency.

Frequently asked questions

How do I convert MOV to WebM on a Mac?

Open this page in Safari or Chrome, drop the MOV on the converter and press Convert to WebM. A minute of 1080p takes a few seconds and saves under the same name ending in .webm. QuickTime Player cannot export WebM, so on a Mac the other options are ffmpeg or HandBrake.

Can I convert a MOV to WebM and keep the transparency?

Not in a browser. Export the clip as ProRes 4444 and convert it with ffmpeg using -pix_fmt yuva420p, as in “Other ways” above. The WebM shows transparency in Chrome, Edge and Firefox; Safari needs an HEVC-with-alpha MOV instead.

Does WebM support transparency?

Yes. VP8 and VP9 in a WebM can carry an alpha channel, and Chrome, Edge and Firefox show it. Safari plays the same WebM with a solid background.

VP9 or VP8?

VP9. It makes smaller files at the same quality and plays in every current browser, Safari included. VP8 matters only for very old players. This converter always writes VP9.

Why is my WebM bigger than the MOV?

A browser’s VP9 encoder works quickly rather than thoroughly, and a screen recording is already small because most of it stands still. ffmpeg made our recording well under half the size of the browser’s WebM, at the cost of half a minute.

Is my MOV uploaded?

No. It is read and converted in this browser tab, on your computer, and the WebM is saved from there. Nothing leaves the machine, so a long recording does not wait on an upload either.

Is my file uploaded?

No. Your MOV is read, converted and checked on your own computer, so there is no upload and no queue. In Chrome and Edge on a computer files of any size work, written straight to a file you choose; in other browsers, files up to 2.0 GB. We count anonymous page views and whether a conversion worked; when one fails, the event also carries the step, your browser’s error and the file’s codecs, size and length in broad bands, never the file or its name. If a conversion fails you can choose to send us the file, which is deleted within 30 days. See the privacy policy.

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