Convert AVI to MP4
Convert AVI videos to MP4 format instantly in your browser. Modernize old video files for playback on phones, tablets, and streaming platforms. No upload needed, 100% private.
Drag 'n' drop files here, or
click to select files
.avi
Drop your files and click Convert to get MP4
//when_to_use
When to Convert AVI to MP4
- Converting old home videos and camcorder recordings stored as AVI for playback on modern devices
- Uploading legacy AVI files to YouTube, Vimeo, or social media platforms that don't accept AVI
- Playing AVI movies on iPhone, iPad, or Android devices that lack AVI support
- Reducing file size of AVI archives — MP4 with H.264 is typically 50-70% smaller than AVI with DivX
- Editing old AVI footage in modern video editors like iMovie, CapCut, or Adobe Premiere that prefer MP4
//comparison
AVI vs MP4
| Property | AVI | MP4 |
|---|---|---|
| Container | AVI (1992, Microsoft) | MPEG-4 (modern standard) |
| Video codec | DivX / Xvid / MPEG-4 Part 2 | H.264 |
| Audio codec | MP3 / PCM / AC3 | AAC |
| Typical file size (1 hr video) | 700 MB - 1.4 GB | 300-600 MB |
| Device support | PC only, limited mobile | Universal |
| Streaming | Not supported | Optimized (faststart) |
//how_it_works
How It Works
Drop your AVI video
Drag and drop or select an AVI file. Any AVI works — DivX, Xvid, MPEG-4, or uncompressed. First use loads FFmpeg WASM (~30MB).
FFmpeg decodes AVI container
FFmpeg WASM reads the AVI container in your browser, identifying and decoding the video stream (DivX/Xvid/MPEG-4) and audio stream (MP3/PCM/AC3).
Modern H.264 + AAC encoding
Video is re-encoded to H.264 (libx264), audio to AAC. The modern codec achieves dramatically better compression — expect 50-70% smaller files than the AVI original.
Download your MP4
Your modernized MP4 plays on every device. Share on social media, stream to your TV, or edit in any modern video tool.
// under the hood
AVI is Microsoft's legacy container format, often containing DivX, Xvid, or MPEG-4 Part 2 video with MP3 or PCM audio. Our converter uses FFmpeg WASM to decode the AVI container and re-encode as MP4 with H.264 video (libx264) and AAC audio. H.264 typically achieves 50-70% better compression than legacy AVI codecs. The +faststart flag optimizes for progressive web playback.
//faq
Frequently Asked Questions
- What is AVI format?
- AVI (Audio Video Interleave) is a multimedia container format introduced by Microsoft in 1992. While once the standard for PC video, AVI files are large and poorly supported on modern devices like smartphones and Smart TVs. AVI can contain various codecs including DivX, Xvid, and MPEG-4.
- Why convert AVI to MP4?
- MP4 is the modern universal standard. AVI files often won't play on phones, tablets, or Smart TVs, and most social media platforms reject AVI uploads. MP4 with H.264 plays everywhere and typically produces smaller files than AVI.
- Will I lose video quality?
- The video is re-encoded from the AVI codec (DivX, Xvid, etc.) to H.264 at high quality. For most content, the output looks identical or even better than the original, especially if the AVI used older codecs. H.264 is more efficient than legacy AVI codecs.
- Can I convert large AVI files?
- Yes, but since everything runs in your browser, we recommend files under 500MB for the best experience. AVI files are often large because the format uses less efficient compression. The resulting MP4 will usually be significantly smaller.
- Are my files secure?
- Completely. Your AVI files are processed entirely in your browser using FFmpeg compiled to WebAssembly. Nothing is uploaded to any server. We have zero access to your video files.