.avi.mp4
How to Convert AVI to MP4
To convert AVI to MP4, upload your .avi file above, select MP4, and download a modern video that plays on phones, browsers, and TVs. AVI files are typically legacy footage with old codecs (DivX, Xvid) that modern devices can't decode — converting to H.264 MP4 rescues the content and usually cuts the file size by 50–80% with no visible quality change.
This page is part of the Video Converter hub, which covers every video format pair JoltFile supports.
In-browser video limit: 1 GB per file
Browser-based processing — your files never leave your device
Need files over 1 GB, batch conversion, or keyboard shortcuts?
JoltFile desktop appHow to convert AVI to MP4 in 5 steps
The whole process takes under two minutes and requires no software installation or account. Your original AVI file is never modified.
Upload your AVI file
Drag your .avi file onto the converter above, or click “Browse files” to select it from your device. Files are processed locally in your browser whenever possible — nothing is uploaded to a server.
Confirm the output format is MP4
The converter defaults to AVI → MP4 on this page. If you dropped in a different file type, set the target format to MP4 (.mp4) using the format menu.
Adjust quality settings
Pick a resolution and quality preset. 'High' keeps the source resolution and is visually transparent; lower presets shrink the file for messaging and email.
Convert the file
Click “Convert”. JoltFile processes the file and shows a progress indicator — most video conversions finish in a few seconds.
Download your MP4 file
Save the converted .mp4 file to your device. The original AVI file is never modified, and temporary data is discarded automatically.
What happens to quality when converting AVI to MP4?
AVI-era codecs compress poorly by modern standards, so H.264 re-encoding at visually-transparent quality typically yields much smaller files. The conversion can't restore detail lost in the original, but it won't remove any either at reasonable quality settings. Audio moves to AAC. Very old AVI files with exotic codecs may need a decode step first — JoltFile handles common variants automatically.
When should you convert AVI to MP4?
- Rescuing old camcorder and DV footage for modern playback
- Playing legacy video archives on phones and smart TVs
- Uploading old clips to YouTube or social media
- Archiving AVI libraries in a space-efficient format
AVI vs MP4: format comparison
| Property | AVI | MP4 |
|---|---|---|
| File extension | .avi | .mp4 |
| Full name | Audio Video Interleave | MPEG-4 Part 14 |
| Compression | Container (usually lossy codecs) | Lossy container (usually H.264/H.265) |
| MIME type | video/x-msvideo | video/mp4 |
| Introduced | 1992, by Microsoft | 2001, by MPEG |
| Best for | Legacy footage archives; convert to MP4 for any modern use | Sharing, streaming, and uploading video anywhere |
About the AVI and MP4 formats
What is AVI? (Audio Video Interleave)
AVI is Microsoft's legacy video container from 1992. It was the dominant PC video format of the 1990s and 2000s, so vast archives of older footage exist as .avi files — often with codecs (DivX, Xvid) that modern devices no longer ship.
Strengths
- Huge legacy archive compatibility
- Simple, well-documented structure
- Supports many codecs
- Still plays in VLC and most desktop players
Limitations
- No native support in modern browsers or phones
- Large files — predates modern compression
- No native support for modern features like chapters or streaming
What is MP4? (MPEG-4 Part 14)
MP4 is the most universally supported video container format, standardized by MPEG in 2001. Almost always paired with H.264 or H.265 video and AAC audio, it plays natively on every modern browser, phone, TV, and social platform.
Strengths
- Plays on virtually every device and platform
- Excellent quality-to-size ratio with H.264/H.265
- Supports subtitles, chapters, and multiple audio tracks
- Required or preferred by every major social platform
Limitations
- Lossy — re-encoding always costs quality
- Not ideal for professional editing (intra-frame codecs win there)
- H.265 variants can fail on older hardware
AVI to MP4 conversion: your questions answered
Why won't my AVI file play on my phone or browser?
AVI is a 1992 container, and the codecs typically inside it (DivX, Xvid, MJPEG) never shipped on mobile OSes or browsers. Converting the streams to H.264/AAC inside MP4 makes the content playable everywhere.
Will I lose quality converting old AVI footage?
Not visibly at high quality settings — and you'd never recover more than the AVI contains anyway. Use a high quality preset for archival conversions and keep the original AVI as backup.
How much smaller will the MP4 be?
Commonly 50–80% smaller. Legacy codecs predate two decades of compression research, so H.264/H.265 achieves the same visible quality in a fraction of the bytes.
Is it free to convert AVI to MP4 with JoltFile?
Yes. JoltFile's free tier covers everyday AVI to MP4 conversions with no account and no watermarks. Higher file-size limits and batch processing are planned for the upcoming Pro tier.
Is my AVI file private when I convert it?
Yes. JoltFile is designed around browser-based processing: whenever technically possible your file is converted locally on your own device and never uploaded to a server. Files that do require server processing are encrypted in transit and deleted automatically after conversion.
FAQ provided by JoltFile.