CalcBrew

Video Converters

AVI to MP4

Old family videos, dashcam clips and capture-card recordings in AVI or WMV become MP4s you can watch on a phone, share in a chat or upload anywhere.

By Miikka · CalcBrew · Updated

Runs in your browser — files never leave your device.

Drop AVI, WMV files here

or click to browse · paste from clipboard · up to 300 MB each

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Why convert AVI to MP4

AVI is a 1990s container that predates modern codecs; the video inside is usually DivX, Xvid, MJPEG or DV, none of which browsers or phones decode. Conversion to H.264 MP4 is the only route to universal playback.

Browsers cannot decode these codecs natively, so this page loads FFmpeg compiled to WebAssembly (about 30 MB, once) and converts the file on your device with the same decoders desktop tools use. It is slower than a native app — expect roughly real time or longer for standard-definition footage — but nothing is uploaded. Interlaced DV footage can be deinterlaced, and the 4:3 or 16:9 aspect ratio is preserved.

How to convert AVI, WMV to MP4

  1. Drop AVI, WMV files onto the box above, click it to browse, or paste from the clipboard.
  2. Adjust the options if you need to — the defaults suit most cases.
  3. Press Convert. The work happens on your device, so speed depends on your computer or phone.
  4. Download the MP4 — individually or all at once.

About the formats

AVI · Audio Video Interleave · .avi

Microsoft’s 1992 video container, still produced by older camcorders, dashcams and capture cards; large files and no support on phones.

  • AVI has no standard for streaming or modern codecs, so files are usually DivX/Xvid or uncompressed.
  • AVI cannot store variable frame rates or modern subtitle tracks.
  • Converting AVI to MP4 always re-encodes the video.

WMV · Windows Media Video · .wmv

Microsoft’s proprietary video format from Windows Movie Maker and old PowerPoint exports; not playable on Apple devices or in browsers.

  • WMV was the default output of Windows Movie Maker until 2012.
  • Mac and iOS have no built-in WMV support.
  • Converting to MP4 is the standard way to share or upload WMV footage.

MP4 · MPEG-4 Part 14 video · .mp4

The video format that works everywhere: phones, TVs, browsers, social networks. Normally H.264 video with AAC audio.

  • MP4 is a container; the codec inside (H.264, HEVC/H.265, AV1) decides what can play it.
  • H.264 MP4 is the safe choice for uploads and sharing; HEVC MP4 from newer iPhones needs extra codecs on Windows.
  • The “moov atom” placement decides whether a browser can start playing before the whole file downloads.

Related conversions

MOV to MP4PopulariPhone/Mac MOV to MP4, usually without re-encoding.Video ConverterAny video format to any other, with codec options.Compress VideoPopularMake a video small enough for email, WhatsApp or uploads.MKV to MP4PopularMKV to MP4 by remuxing, lossless and fast.WebM to MP4PopularBrowser screen recordings (WebM) to MP4.MP4 to WebMOn-deviceMP4 to smaller WebM (VP9/Opus) for websites.

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Cite this calculator
APACalcBrew. (2026). AVI to MP4. https://calcbrew.com/avi-to-mp4
MLA“AVI to MP4.” CalcBrew, 2026, calcbrew.com/avi-to-mp4.

Link to https://calcbrew.com/avi-to-mp4. Results are estimates; cite the underlying formula or data source for academic work.