Free WMV to MP4 Converter For files Windows Media left behind
WMV is Windows Media Video, a Microsoft format that lives inside an ASF container. It was everywhere in corporate training libraries, Windows Movie Maker projects and old PowerPoint exports, and it is now refused by Macs, iPhones, most editors and most upload forms. This page re-encodes it to H.264 MP4 inside your browser tab, with nothing uploaded. Be warned that none of WMV's streams can be carried into MP4 as they are, so this is a full re-encode and it takes real time to run.
- Nothing uploaded
- H.264 MP4 out
- Up to 20 files
Convert WMV to MP4
MP4, MOV, M4V, MKV, AVI, WMV, WebM, TS, MTS and more
Up to 20 clips at once
Privacy-first. No uploads. If this helps, share it.
- The file stays in this tab
FFmpeg compiled to WebAssembly does the decoding and the encoding inside your browser. That matters here, because WMV archives are usually internal material: compliance training, a recorded all hands meeting, old client work, a screen capture with somebody's desktop in frame.
- Slow, and honest about it
WMV holds VC-1 or WMV3 video with WMA audio, and so for broad compatibility this converter decodes them and writes H.264 with AAC instead of trying to preserve the original Windows Media streams. The browser build runs on a single thread, so budget roughly the length of the video itself. A 45 minute training module is roughly a 45 minute job.
- 20 files per batch, 1 GB each
Point it at a folder of old .wmv files and they queue up one after another. Take each MP4 as it lands or grab the whole set as a zip at the end.
How to convert WMV to MP4
Add your .wmv file, leave the output set to MP4, and it is re-encoded to H.264 video with AAC audio right here in the page, then saved to your device. Nothing is sent to a server at any point. WMV cannot be repackaged into MP4 the fast way, so the encode runs at roughly the speed the video plays. Start a long one and leave the tab open.
- Add your WMV files
- Leave the output on MP4
- Save the H.264 MP4
WMV vs MP4, line by line
WMV is not really one thing. The extension names a container, ASF, and inside it sits Microsoft video, usually VC-1 or WMV3, alongside WMA audio. None of those belong in an MP4 that plays widely, which is why this conversion is never a quick repackage. Here is what actually changes on the way across.
| What changes | WMV source | MP4 output |
|---|---|---|
| Container | ASF, the Advanced Systems Format Microsoft built for Windows Media | MP4, the ISO container almost every player and phone reads |
| Video codec | VC-1 or WMV3, sometimes the older WMV1 and WMV2 variants | H.264, decoded in hardware on essentially every modern device |
| Audio codec | WMA, occasionally WMA Pro or WMA Lossless | AAC, the audio track MP4 players expect to find |
| Where it opens | Windows Media Player and old Windows software, and not much else | iPhone, Android, Mac, Safari, editors, TVs, upload forms |
| File size | Whatever the original Windows Media encoder settings produced | Often similar or a little smaller, but this is a converter and not a compressor, so no size is targeted |
Some files with a .wmv extension are plain ASF, and some .asf files are really WMV. Both take the same path here, so the extension does not decide anything.
Why converting WMV is worth the wait
WMV lost. Microsoft stopped pushing it, Apple never shipped Windows Media support and the third party plugin that used to add it was discontinued, and the major editors either refuse WMV outright or handle it badly because the format was built for streaming rather than editing. Windows Media Player still opens these files on a Windows PC, which is exactly why old libraries sit untouched for years, right up until somebody needs one on a phone, in a timeline, or on a site that only takes MP4. Converting once turns a file that depends on a single ageing application into one that opens almost anywhere.
The tradeoff is real: this is a re-encode, so the output is a fresh generation of compression rather than a copy of the original. Most WMV files were encoded at modest bitrates to begin with, so the visible cost is usually small, but it is not zero, and nothing here can make an old file look better than it did. Keep the WMV if it is your only master.
What plays it now that Windows Media does not
The output is an MP4 carrying H.264 video alongside an AAC soundtrack, the combination iPhones, Android phones, browsers, smart TVs, PowerPoint, Google Slides, editors and upload forms all accept without argument. What a conversion cannot do is repair whatever was already wrong with the picture.
Plays as it is on iPhone and Android, in Safari and Chrome, in QuickTime and VLC, and it imports into Premiere, Final Cut and DaVinci Resolve.
Still soft if the source was soft. A 320 by 240 clip from 2006 is still 320 by 240 afterwards, only in a format things will open. Nothing here upscales, sharpens or deinterlaces.
Still not an editor. This tool converts, and it can pull the soundtrack out as an MP3, but it cannot trim length, crop, change the aspect ratio or unstretch a 4:3 recording that was flagged as widescreen.
Three steps, and then a wait
All of it happens in this tab.
Add your WMV files
Drop up to 20 of them in, 1 GB each, or browse your device. Training modules, Movie Maker exports and old screen captures sit comfortably inside that.
Leave the output on MP4
The To dropdown beside the file also offers MP3, at 128 kbps and 44.1 kHz, for when all you want out of an old recording is what was said. For video, MP4 is the one.
Wait, then save it
Progress runs per file and the queue works through them one at a time. Save each MP4 on its own, or take the whole batch as a single zip.
Why use this converter for WMV in particular
WMV files tend to be old, internal, and the only copy anybody has. That changes what matters when you pick something to run them through.
Old files are usually sensitive files
The WMV sitting on a shared drive is often a recorded internal meeting, an HR module or a client project from years back. Handing that to an upload based service to fix an extension is a poor trade. Here the page reads the file and it goes nowhere else.
Nothing to install on a locked down machine
The standard advice for WMV is to install VLC, HandBrake or a codec pack. On a managed work laptop you frequently cannot. A browser tab needs no admin rights and leaves nothing behind on the machine.
It does not mind what you actually dropped
A fair share of what people call a WMV turns out to be an AVI, an old MPEG, or an ASF someone renamed by hand. Drop it in anyway. Whatever really arrived gets detected and converted, and the label on the card is corrected to match.
The whole folder in one pass
WMV is rarely a one file problem. It is a directory of them, written by the same software in the same year. Twenty at a time, no clicking through them individually, no queue position and no daily allowance.
Nothing about the file reaches us
Converting a video usually means uploading it to a stranger's server, waiting in their queue and trusting their deletion policy. For a decade old corporate recording, that is a bigger decision than the file size makes it look.
Here the work is done by a WebAssembly build of FFmpeg running in the page you are reading. Your browser opens the file, writes the MP4 into memory and hands it to you. We have no copy to keep, no retention window to explain and no sign in to tie any of it to a person.
What that means in practice
- Your browser reads the video, no server ever does
- We never see the file, its contents or its name
- No account, no watermark and no daily cap on conversions
- Your own CPU encodes, so a long video ties up the tab
WMV to MP4 troubleshooting
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Add the .wmv file to the converter above, leave the output set to MP4, and save the result once it finishes. Nothing is uploaded, nothing is charged for, and the file you download carries no watermark.
Last reviewed in August 2026 for browser-based WMV conversion.