How to Convert AVI to MP4 Online
Follow these three simple steps to convert AVI to MP4. No software installation required. Free and secure.
Select an AVI Video
Choose an AVI movie, recording, or exported video from your device.
Choose Video and Audio Settings
Keep the original resolution and frame rate or choose new values, then keep the automatic audio settings or select a sample rate and mono or stereo output.
Convert and Download
Start the conversion, review the original and output file sizes, and download the completed MP4 video.
How Does the AVI to MP4 Converter Work?
The CompressFly AVI to MP4 converter reads the supported video and audio streams in your AVI file, re-encodes the picture as H.264 and available audio as AAC, and places them in an MP4 container. Resolution, frame rate, sample rate, and channel settings can be adjusted before conversion.
Conversion runs directly in your browser. Your AVI video is not uploaded to a server, and the completed MP4 file downloads from the browser to your device.
What "directly in your browser" means
- Your AVI video is not uploaded to a server.
- Video conversion runs locally on your device.
- The completed MP4 video downloads directly from your browser.
When to Convert AVI to MP4
Convert AVI to MP4 when a legacy AVI file does not fit a modern playback, publishing, or delivery requirement.
Improve Device Compatibility
Create an MP4 copy for a phone, tablet, television, or media player that has limited AVI support.
Prepare AVI for Upload
Convert an AVI file before adding it to a website, social platform, cloud workflow, or online editor that requests MP4.
Update a Video Archive
Make a broadly playable MP4 copy while keeping the original AVI as the source archive.
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AVI to MP4 Converter FAQ
How do I convert AVI to MP4 online?
Use this online AVI to MP4 converter in three steps: 1. Select an AVI video from your device. 2. Keep or change the available video and audio settings. 3. Start the conversion and download the completed MP4 video.
What happens when I convert AVI to MP4?
The AVI video is decoded and re-encoded as H.264 with available audio encoded as AAC inside the new MP4 file.
Why is MP4 often easier to use than AVI?
AVI can contain older codecs that current devices and web platforms do not consistently accept. H.264 video with AAC audio in MP4 has broader support in modern playback and upload workflows.
Can I change the video resolution and frame rate?
Yes. Keep the source resolution and frame rate or select an available output resolution and frame rate before conversion.
Will converting AVI to MP4 make the file smaller?
Not necessarily. The output size depends on the source video, selected resolution, frame rate, audio settings, duration, and visual content. Use the Video Compressor when reducing file size is the main goal.
Is the AVI to MP4 converter free?
Yes. Convert AVI to MP4 for free with no registration or credit card required.
Is there a file size limit, and is my video uploaded?
Your video is processed locally in your browser and is not uploaded to a server, so there is no server upload limit. The practical limit depends on your device's available memory and processing power, as well as the video's duration and resolution.