How to Convert AVI to MP4

AVI (Audio Video Interleave) is a Microsoft container format from 1992. It played a major role in the early days of digital video but has been largely superseded by MP4. Modern phones, web browsers, smart TVs, and streaming devices all prefer MP4. AVI files often won’t play, won’t upload, or look broken in newer environments.

Conversion is fast and usually lossless.

The fastest path: HandBrake (free)

HandBrake handles AVI → MP4 cleanly:

Install HandBrake (Windows/Mac/Linux)
Open HandBrake, drag in your .avi file
Choose preset: “Fast 1080p30” or match source resolution
Set output filename ending in .mp4
Click Start Encode

For typical AVI content (MPEG-4 or DivX video), output is a fully compatible MP4.

Lossless option: FFmpeg

If your AVI contains compatible codecs (H.264 video + MP3/AAC audio), you can remux without re-encoding:

ffmpeg -i input.avi -c copy output.mp4

Instant. Lossless. Same file size as source.

If codecs aren’t directly compatible:

ffmpeg -i input.avi -c:v libx264 -c:a aac output.mp4

Re-encodes; slower but produces a guaranteed-compatible MP4.

Why AVI is problematic today

No streaming support: AVI wasn’t designed for progressive download; videos play only after fully downloading
Codec confusion: AVI is a container that can hold many codecs (DivX, XviD, MJPEG, etc.); compatibility varies
No subtitle support: AVI doesn’t cleanly support modern subtitle formats
Large files: older AVI codecs are less efficient than modern H.264/H.265
Limited mobile support: most phones don’t play AVI

MP4 fixes all of these.

When the AVI is from a specific era

Old DV camcorder AVIs: from MiniDV tapes in the 2000s. Convert to MP4 at original resolution for archival.

Screen recordings as AVI: older Windows screen recorders saved AVI. Convert with HandBrake.

DivX/XviD content: peer-to-peer era movie files. HandBrake handles these fine.

Lossless AVI (uncompressed or with codecs like Lagarith): huge files. Convert with care to preserve quality if needed.

What gets preserved

Preserved in conversion:

Video content
Audio tracks (most cases)
Basic synchronization

Sometimes lost or changed:

Subtitle tracks (AVI’s subtitle support is limited; convert separately if subtitles matter)
Multiple audio tracks (handle case-by-case)
Aspect ratio metadata (verify after conversion)

For typical “single video + audio” AVIs: lossless conversion preserves everything.

On phone

For converting AVI on mobile:

iPhone/Android: AVI playback is limited natively. Most users won’t have AVIs on their phones, but if they do:

Use a third-party converter app
Or transfer to a desktop for conversion

Browser-based AVI conversion isn’t reliable for the same computational reasons covered in our video compression guide.

After conversion

Extract audio: MP4 to MP3 for audio-only use
Compress: Compress Video for smaller files
Trim: see our Trim or Cut Video guide
Rotate if sideways: see Rotate a Video

TL;DR

AVI → MP4: usually a clean conversion
Lossless when possible: ffmpeg -i input.avi -c copy output.mp4
With re-encoding: HandBrake for a GUI, or FFmpeg with codec args
Why convert: AVI is outdated; MP4 plays everywhere in 2026
For audio only: MP4 to MP3 after conversion