Convert AVI to MP4

Why convert AVI to MP4?

AVI is one of the oldest video formats still around. It was the standard on Windows in the 1990s and 2000s, so you will find AVI files from old digital cameras, camcorders, DVD rips, dashcams, security cameras and early downloads. Many of them use codecs like DivX, Xvid or MJPEG that modern phones, Macs, smart TVs and social apps do not support. Converting AVI to MP4 re-encodes the video to H.264 with AAC audio, the most widely supported combination there is, so the file plays on iPhone, Android, Mac, Windows, YouTube, Facebook and WhatsApp without extra software.

How this AVI to MP4 converter works

Because AVI files use older codecs that browsers cannot decode on their own, VideoToolsFlow uses a built-in version of FFmpeg, the same engine used by professional video software. It is compiled to run inside your browser and loads only when you add an AVI file, so the page stays light for everyone else. The video is converted to H.264 at a good-quality setting, the audio to AAC, and the result is saved as a standard MP4 file.

The conversion happens on your own device. Your AVI is never uploaded, which matters for family videos, camera footage and anything private. It also means there is no file size cap set by a server and no waiting for an upload to finish.

How to convert AVI to MP4

1. Drop an .avi file on the box above, or tap to choose it.
2. Press Convert. The first time, the converter engine is downloaded once (about 30 MB), then the progress bar shows the conversion.
3. Download your MP4. It keeps the original name with a .mp4 extension.

Converting AVI is real work for your device, because every frame is decoded and encoded again. Short clips take seconds. Longer videos can take several minutes, and a computer is faster than a phone. Keep the tab open until it finishes.

Quality and file size

The resolution and frame rate of your AVI are kept. H.264 is much more efficient than old AVI codecs, so the MP4 is often smaller than the original while looking the same. Old MJPEG files from cameras usually shrink a lot. If the original was low quality, such as a 480p DVD rip or an old phone clip, the MP4 will look the same as the original, not better, because conversion cannot add detail that was never recorded.

Tips for old AVI videos

• Very large files: convert on a computer with enough free memory. If a file is too big, cut it into parts first.
• Sideways video: fix it after converting with the rotate video tool.
• Sharing by email or chat: shrink the MP4 with the video compressor or compress video for email.
• Only need the sound: use video to MP3 to save the audio.

AVI vs MP4

AVI and MP4 are both containers that hold video and audio. AVI was designed long before streaming and phones, and it lacks features modern players expect, such as good support for B-frames, modern codecs and fast-start playback. MP4 was built for exactly that, which is why it has become the default for cameras, phones and the web. Unless an old program specifically needs AVI, MP4 is the better format to keep.

Converting many old videos

If you are digitizing a box of old camera clips, convert one file first to check the result and see how long it takes on your device. Then convert the rest one at a time and keep the tab in the foreground, because browsers slow down background tabs. When everything is converted and checked, you can archive the original AVI files or delete them to free up space.

Convert other video formats

For other files, try MKV to MP4, MOV to MP4 or WebM to MP4. The video converter can turn any supported video into MP4, MOV, WebM or MKV.