How to Convert AVI to MP4
- Add your video — Drag and drop an AVI file into the upload area, or click "browse files" to select one from your computer.
- Wait for conversion — The converter engine loads automatically (about 31MB on first use, cached for future visits). Your video is re-encoded to MP4 right in your browser.
- Download — Click "Download MP4" to save the converted file. The output uses high-quality H.264 encoding.
What is an AVI File?
AVI (Audio Video Interleave) is a multimedia container format introduced by Microsoft in 1992 as part of its Video for Windows technology. For over a decade, AVI was the default video format on Windows PCs. You'll still find AVI files from older camcorders, surveillance camera systems, screen recording software, and archived video collections. While AVI can hold high-quality video, it uses outdated codecs like DivX, Xvid, and MPEG-4 Part 2 that modern devices don't support.
Why Convert AVI to MP4?
AVI files have two major problems: they're huge and they're incompatible with modern devices. A 10-minute AVI video can be 500MB or more, while the same video in MP4 might be 50-100MB with identical visual quality. iPhones, iPads, Android phones, smart TVs, and web browsers don't support AVI playback. Converting to MP4 with H.264 encoding dramatically reduces file size while ensuring your video plays on every device, can be shared on social media, and uploads faster to cloud storage.
Is the Quality Preserved?
The converter re-encodes AVI files using H.264 (the most widely supported video codec) with high-quality settings. Since AVI codecs like DivX and Xvid are not MP4-compatible, re-encoding is necessary — but the output is visually identical to the original for most content. The resulting MP4 file is typically much smaller than the original AVI, with no noticeable quality loss.
Supported Input Formats
.avi
Supports AVI files with common video codecs (DivX, Xvid, MPEG-4, MJPEG, H.264) and audio codecs (MP3, PCM, AC3, WMA). The converter handles most AVI files from camcorders, surveillance systems, and legacy recordings.
Frequently Asked Questions
Is this AVI to MP4 converter free?
Yes, completely free. No sign-up, no hidden fees, no watermarks. Convert as many videos as you need.
Are my videos uploaded to a server?
No. All processing happens locally in your browser using WebAssembly (ffmpeg.wasm). Your files never leave your device. We never see, store, or have access to your files.
How long does the conversion take?
The first time you use the tool, it downloads the converter engine (~31MB). This is cached by your browser for future visits. AVI files require re-encoding, which takes longer than a simple remux — expect a few minutes for files over 100MB, depending on your device speed.
Is there a file size limit?
There's no hard limit, but since conversion happens in your browser's memory, very large files (over 500MB) may be slow or cause issues. For best results, keep files under 500MB.
Will the video quality be the same?
The converter re-encodes using high-quality H.264 settings (CRF 23), producing output that is visually identical to the original. The MP4 file will also be significantly smaller than the original AVI.
What devices does this work on?
This converter works on any device with a modern web browser — Windows, Mac, Chromebook, and Linux. Mobile devices may have limited memory for large files. No software to install.
What is an AVI file?
AVI (Audio Video Interleave) is a video format created by Microsoft in 1992. It was the standard PC video format for years and is still common in older recordings, surveillance cameras, and archived video collections. AVI files tend to be very large and aren't supported by modern phones, tablets, or smart TVs. Converting to MP4 solves both problems.