How do I convert AVI to MP4?

Add your AVI file to the upload area above, then press Convert. The MP4 file downloads straight to your device. You do not need an account, and there is no watermark.

Are my files uploaded to a server?

No. This conversion runs entirely inside your browser using WebAssembly, so the file never leaves your device — you can even disconnect from the internet after the page loads and it will still work.

Does converting to MP4 reduce quality?

MP4 uses lossy compression, so some data is discarded. At the default quality the difference is very hard to see or hear; raise the quality setting if you need to be certain, at the cost of a larger file.

How large a file can I convert?

Up to 512 MB per file for this conversion. Because the work happens in your browser, the practical limit is your device's memory — larger files work on a desktop with plenty of RAM and may fail on an older phone.

Can I convert several files at once?

Yes. Add as many as you like and press Convert All. Each file is processed independently, so one failure does not stop the rest, and you can download everything together as a ZIP.

Can I use this on my phone?

Yes. FileTools360 works in mobile browsers on iOS and Android, including choosing files straight from your camera roll. Very large videos may run out of memory on a phone — those are better converted on a laptop.

VideoAdjustable qualityRuns in your browser

AVI to MP4 Converter

Turn AVI files into MP4 in a couple of clicks. Legacy Microsoft container. Widely readable, inefficient. The default video container of the internet. The output is re-encoded, so quality depends on the settings you choose.

On your deviceNever uploadedGone when you close the tabHow this works

Drop your files here

AVI files (.avi) · up to 512 MB each

or paste files from your clipboard

Ready when you are

Drop a AVI file above and FileTools360 will turn it into MP4 — right here on your device, without uploading anything.

⌘K to search converters

How to use it

1
Add your AVI files
Drag them onto the upload area, choose them from your device, or paste them from your clipboard. You can queue several at once.
2
Adjust the settings if you want to
The defaults suit most people. Open Advanced to control codec, resolution and bitrate, the audio track and start and end times.
3
Convert and download
Press Convert. Everything happens on your own device — nothing is uploaded. Download files one by one, or grab them all as a ZIP.

AVI and MP4 explained

AVI is a Microsoft container from 1992. It predates modern video compression and lacks features taken for granted today, such as proper support for variable frame rates and modern codec metadata.

MP4 is a container, not a codec. It usually holds H.264 video and AAC audio, and that specific combination is the closest thing the internet has to a universal video format.

Where AVI files come from: Old camcorders, legacy Windows software and archived downloads.
Where MP4 is used: Phone cameras, screen recorders, and every video streaming platform.

AVI vs MP4

The two formats solve different problems, which is why converting between them involves trade-offs rather than a straight upgrade.

AVI compared with MP4
Property	Source	Target
Compression	Container (depends on codec)	Container (depends on codec)
Animation	Yes	Yes
Introduced	1992	2001
Browser support	Wide but dated. Not supported in browsers.	Plays on effectively every device.

AVI is stronger at: Readable by very old software. Simple, well understood structure.
MP4 is stronger at: Plays on effectively every device and browser without extra software. Supported by every editor, platform and social network. Efficient compression with H.264 or H.265.

Why convert AVI to MP4?

People make this switch when they run into the limits of AVI: almost always. Converting to MP4 is nearly always the right move. MP4 is the better fit when you want the video to simply play, anywhere, for anyone.

AVI limitations that prompt the switch: Inefficient — much larger than MP4 for the same quality. No browser support. Poor handling of modern codecs and variable frame rate.
What you give up: H.264 carries patent licensing obligations for commercial distribution at scale. Less flexible than MKV for multiple audio tracks and subtitles.

Does converting AVI to MP4 reduce quality?

Both formats store the content without discarding data, so this conversion preserves it exactly. The file size may change because the two formats compress differently, but the content itself is unaffected.

“MP4” tells you nothing about quality. An MP4 can hold anything from a pristine 4K master to a heavily compressed clip.

About these formats

Source

Audio Video Interleave

Legacy Microsoft container. Widely readable, inefficient.

Extensions: .avi
MIME type: video/x-msvideo
Best for: Older Windows software · Legacy hardware
Compatibility: Wide but dated. Not supported in browsers.

Target

MPEG-4 Part 14

The default video container of the internet.

Extensions: .mp4, .m4v
MIME type: video/mp4
Best for: Sharing anywhere · Streaming · Social media
Compatibility: Plays on effectively every device.

Good to know