How to Convert AVI to MP4 Online Free

A complete step-by-step guide to converting old AVI video files to the modern MP4 format - instantly, for free, right in your browser.

1-3min Conversion time
100% Private
Free — No registration

What is AVI to MP4 Conversion and Why Do It?

AVI (Audio Video Interleave) was introduced by Microsoft in 1992 and was the dominant video format for many years. Old home videos, downloaded clips, and legacy recordings are often in AVI format.

MP4 is the modern standard that works on every device, platform, and application. Converting AVI to MP4 makes your old videos playable everywhere - on iPhones, Android phones, smart TVs, YouTube, and any editing software - without compatibility issues.

AVI

What is AVI Format?

AVI (Audio Video Interleave) is a multimedia container format from Microsoft. It can use many different video codecs including DivX, Xvid, and MPEG-4. AVI was widely used in the 1990s and 2000s for downloadable video.

AVI files are often very large because many use older, less efficient codecs. While Windows Media Player supports AVI, modern devices like iPhones, iPads, and most Android phones cannot play AVI files without additional apps.

MP4

What is MP4 Format?

MP4 (MPEG-4 Part 14) is the current universal video standard, using H.264 compression to deliver excellent quality at small file sizes. It is supported natively on every device and platform.

MP4 is required or preferred by YouTube, Vimeo, Instagram, TikTok, and all streaming platforms. Every modern video player, phone, tablet, TV, and editing software supports MP4.

Why Convert AVI to MP4?

Play on Any Device

AVI files cannot play on iPhones, iPads, or many Android devices without special apps. MP4 plays natively on all modern devices without any additional software.

Upload to Online Platforms

YouTube, Vimeo, Instagram, and other platforms prefer or require MP4. Converting AVI to MP4 ensures fast, reliable uploads without format rejection.

Smaller File Sizes

AVI files using old codecs are often very large. Re-encoding to MP4 H.264 can dramatically reduce file size while maintaining good visual quality.

Video Editing Compatibility

Modern video editing software like DaVinci Resolve, Premiere, and iMovie work best with MP4. Converting AVI files first ensures smooth importing and editing.

How to Convert AVI to MP4 - Step by Step

1

Open the AVI to MP4 Converter

Go to the free AVI to MP4 converter tool. No registration or software download required - it runs entirely in your browser.

2

Upload Your AVI File

Click "Choose File" or drag and drop your AVI video into the upload area.

3

Convert to MP4

The conversion re-encodes your AVI video to MP4 H.264 format. Conversion time depends on file size.

4

Download Your MP4

Click the Download button to save your MP4 file, ready to play on any device or upload to any platform.

Ready to Convert AVI to MP4?

Use our free browser-based converter - no uploads, no registration, instant results.

Convert AVI to MP4 Free

Tips for Best Results

Large AVI Files Take Time

Old AVI files are often several GB in size. Browser-based conversion works best for files under 500 MB. For very large AVI files, a desktop tool may be faster.

Check Quality Settings

Choose a quality setting that matches your needs. High quality for archiving, medium for sharing - this lets you balance quality against file size.

Update Your Video Library

If you have a large collection of old AVI files, batch converting them all to MP4 is worth doing - you will be able to play them on any device in the future.

Frequently Asked Questions

Why won't my AVI file play on my iPhone?

iPhones do not support AVI format natively. Converting to MP4 makes the video playable on all Apple devices without needing additional apps.

Will converting AVI to MP4 reduce video quality?

There is some quality reduction during re-encoding, but at high quality settings it is minimal. The resulting MP4 will look comparable to the original AVI.

Is my video safe when converting online?

Yes - our converter processes files in your browser. Your video is never uploaded to any server, ensuring complete privacy.

How much smaller will the MP4 be compared to the AVI?

It varies depending on the original AVI codec. Videos using old Xvid or DivX codecs can be re-encoded to MP4 H.264 at 30 to 60% smaller size with similar quality.

Can I convert AVI files with subtitles?

The video and audio tracks are converted, but embedded subtitle tracks may not transfer to the MP4. Hard-coded burned-in subtitles in the video will remain visible.

Need More Help?

Our AVI to MP4 converter is free to use with no limits - convert as many files as you need. All processing happens in your browser for complete privacy.

Have questions? Visit our FAQ page or contact us. We also offer converters for dozens of other image, audio, video, and document formats.

Convert AVI to MP4 Free