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Convert AVI to MP4

Free AVI to MP4 converter that runs in your browser. No upload, no signup, no watermark. Files never leave your device.

Conversion Successful
100% local. Your file is processed in this tab and never uploaded.

How to Convert AVI to MP4

Four steps. No uploads, no account, no waiting.

1

Upload your AVI file

Drag and drop your AVI file into the converter above, or click to browse and select it from your device. Files stay on your machine and are never uploaded to a server.

2

Select MP4 as the output format

Open the output format picker and choose MP4. The converter automatically detects the input and only shows compatible output formats for your file.

3

Adjust settings (optional)

Use the sliders icon to trim, crop, resize, rotate, mute or rebalance audio, and pick an output quality before converting.

4

Convert and download

Click Convert to run the conversion in your browser. The output MP4 file downloads automatically when ready, with no server round-trip and no watermarks.

Why Convert AVI to MP4?

AVI is a legacy Windows Media container from the 1990s that lacks hardware decoding support on modern mobile devices, smart TVs, and streaming platforms.

Converting to MP4 brings video into a modern container with efficient H.264 compression and universal device support from phones to 4K televisions.

AVI
MP4
Container
AVI
Container
MP4 (ISOBMFF)
Typical codec
Various (DivX / XviD / MPEG-4)
Typical codec
H.264 / H.265
Audio codec
MP3 / PCM
Audio codec
AAC
Streaming friendly
No
Streaming friendly
Yes
Device support
Limited on modern devices
Device support
Universal
Typical use
Legacy archives
Typical use
Web, mobile, TV

Related Conversions

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MP4 to MP3
Convert MP4 files to MP3

Frequently Asked Questions

Why can't modern devices play AVI files?
AVI was designed for Windows 9x-era hardware and software. Many modern device players and streaming platforms have dropped AVI support to focus on efficient modern containers.
Will the video and audio stay in sync after conversion?
Yes. The converter carefully handles audio/video synchronization. Older AVI files with VBR audio sometimes have sync issues that the converter corrects during the conversion.
What codec does the output MP4 use?
The output uses H.264 video with AAC audio, the combination supported by virtually every device, browser, and platform.
My AVI file has subtitles. Are they kept?
Subtitle tracks embedded in AVI may not transfer to the MP4 container in the browser version. TeraConvert Desktop preserves embedded subtitle tracks.
Is this conversion really free, and is my file private?
Yes. The browser conversion runs entirely on your device using WebAssembly. Files are never uploaded to a server and are discarded from memory when you close the page. There is no file size tracking, no account link to your upload, and no cloud storage.
Do I need to create an account to convert files?
No. The browser converter works without signing in. An optional account is only needed if you want to save favorites, track conversion history, or upgrade to the desktop app with Polar license activation.
How fast is the conversion?
Most browser conversions complete in a few seconds. Large files (over 100 MB) or heavy formats (video, high-page PDFs) take longer depending on your device's CPU and available memory. The desktop app runs significantly faster using native engines.

Convert AVI to MP4 Faster with TeraConvert Desktop

Batch files. No size limits. Native engine. No browser tab.

Batch convertNo size limitsNative speed100% private
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