AVI to MP4 Converter
Convert legacy AVI video files to universally compatible MP4 online for free. H.264 encoding, 40-60% smaller files. No software needed. Up to 100 MB.
Drop your AVI file hereTap to choose your AVI file
or
Also supports WMV, FLV, MPG, MKV, MOV, WebM • Max 100 MB
How to Convert AVI to MP4
Upload
Drag and drop your AVI video into the converter above, or click Choose AVI File to browse your device.
Convert
Click Convert to MP4. Our server re-encodes your video with H.264 + AAC for universal playback. Takes 30 seconds to 2 minutes.
Download
Click Download MP4 to save the converted video. That's it — no registration, no email required.
Convert AVI to MP4 on Any Device
On Windows 10/11
Windows can play some AVI files through Windows Media Player, but only if the right codecs are installed. AVI files with Xvid, DivX, or older MPEG-4 codecs often require a codec pack. If you need to share videos, upload to social media, or embed in a website, converting to MP4 (H.264 + AAC) eliminates all compatibility issues and produces significantly smaller files.
On Mac
macOS has very limited AVI support — QuickTime Player can open some AVI files but fails with most codecs used in AVI (Xvid, DivX, MS-MPEG4). You need VLC or IINA for playback. Converting AVI to MP4 makes your videos work natively with QuickTime, iMovie, Final Cut Pro, and every macOS sharing method.
On iPhone / iPad
iOS does not support AVI files at all. The Files app cannot preview them, and no built-in app can play them. VLC for iOS can handle AVI, but you lose the ability to share videos via Messages, AirDrop, or social media. Converting to MP4 gives you full iOS integration — playback in all apps and easy sharing.
On Smart TVs & Streaming Devices
Most smart TVs have no AVI support or only handle very basic AVI files. Streaming devices like Roku, Apple TV, and Chromecast do not support AVI playback. Even media centers like Plex may struggle with AVI files containing uncommon codecs. MP4 with H.264 is the universal format that works on every television and streaming device.
What is AVI?
AVI (Audio Video Interleave) is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. For over 15 years, AVI was the dominant video format on Windows PCs, especially during the DivX and Xvid era of the 2000s.
AVI files typically contain video encoded with older codecs like Xvid, DivX (MPEG-4 Part 2), or even uncompressed video, paired with MP3 or PCM audio. The format interleaves audio and video data in alternating chunks, which was efficient for 1990s hardware but has significant limitations by modern standards.
The main drawback of AVI is its age and inefficiency. AVI lacks B-frame support (producing 40-60% larger files than H.264), has no native streaming capability (the entire file must download before playback), no subtitle or chapter support, and very limited metadata. No modern web browser can play AVI files.
What is MP4?
MP4 (MPEG-4 Part 14) is the international standard video container format, published as ISO/IEC 14496-14. It was derived from Apple's QuickTime MOV format in 2001, using the same atom/box architecture for organizing video, audio, and metadata.
MP4 supports H.264 and H.265 video with AAC audio, and includes the faststart flag (moov atom at the beginning) for instant web playback without buffering. It's the recommended upload format for YouTube, Instagram, TikTok, Facebook, and every major platform.
The defining strength of MP4 is universal compatibility. Every computer, phone, tablet, smart TV, gaming console, web browser, and media player manufactured in the last 15 years can play H.264 MP4 files. When you need a video that works everywhere without question, MP4 with H.264 is the safe choice.
AVI vs MP4: Quick Comparison
| Feature | AVI | MP4 |
|---|---|---|
| Developer | Microsoft (1992) | ISO/MPEG (2001) |
| Typical video codec | Xvid, DivX, MPEG-4 Part 2 | H.264, H.265, AV1 |
| Typical audio codec | MP3, PCM, AC-3 | AAC, MP3, AC-3 |
| Compression efficiency | Low (no B-frames) | High (H.264 CRF) |
| Streaming support | None | Full (faststart) |
| Subtitle support | None | Basic (tx3g text) |
| Windows playback | Codec-dependent | Native (H.264) |
| macOS playback | Requires VLC | Native (QuickTime) |
| Smart TVs | Mostly unsupported | Universal |
| Web browsers | Not supported | All browsers (H.264) |
| File size (typical) | Large (legacy codecs) | 40-60% smaller |
| Best for | Legacy archives only | Everything: sharing, web, playback |
Understanding AVI to MP4 Conversion Quality
Unlike MKV-to-MP4 conversion, AVI to MP4 always requires re-encoding. AVI files typically contain Xvid or DivX video (MPEG-4 Part 2), which cannot be directly placed into an MP4 container. The video must be re-encoded to H.264, and the audio is converted to AAC.
The good news: H.264 is so much more efficient than Xvid/DivX that the re-encoded MP4 will be 40-60% smaller at equivalent visual quality. In many cases, the MP4 actually looks slightly better because H.264 has access to B-frames and more advanced motion compensation that Xvid lacks.
Our converter uses FFmpeg with H.264 encoding at CRF 23 (Constant Rate Factor), which produces quality that's indistinguishable from the original for most content. Audio is encoded as AAC at 192 kbps for transparent quality. The -movflags +faststart flag enables instant web playback.
For old camcorder footage that appears interlaced (horizontal lines during motion), our converter applies deinterlacing to produce clean progressive video suitable for modern displays.
Why Convert AVI to MP4?
Massive file size reduction
AVI files with Xvid/DivX video are typically 40-60% larger than H.264 MP4 at the same visual quality. A 700 MB AVI file (a classic "CD rip" from the DivX era) converts to approximately 300-400 MB as MP4. If you have a library of old AVI files, conversion frees up significant storage space.
Universal device compatibility
H.264 MP4 plays on every device manufactured in the last 15 years: Windows PCs, Mac, iPhones, Android phones, smart TVs, gaming consoles, and all web browsers. AVI fails on most of these platforms without additional codec installation.
Social media & web uploads
YouTube, Instagram, TikTok, Facebook, and Twitter all require MP4 with H.264 for uploads. None of these platforms accept AVI files. Converting to MP4 is required before uploading to any social media platform or embedding video on a website.
Preserve legacy footage
If you have old home videos, camcorder recordings, or DVD rips from the 2000s in AVI format, converting to MP4 preserves them in a modern format that will remain playable for decades. AVI codec support is declining every year as Xvid/DivX decoders are removed from modern operating systems.