What you need to know about converting AVI to MP4

An AVI file is an older video format that works on most devices, but MP4 is smaller, plays almost everywhere, and uploads faster to the web. Converting between them takes 5 to 30 minutes depending on your video length and which tool you use. You do not need to buy software — free tools work just as well as paid ones for this task.

The conversion process reads your AVI file and rewrites it as MP4 without losing the video or audio. Your original AVI file stays unchanged. The new MP4 file will be roughly the same size or smaller, depending on the settings you choose.

Key Takeaways

  • Three free tools that work on Windows, Mac, or both are HandBrake, VLC media player, and FFmpeg — each handles AVI to MP4 conversion without cost.
  • HandBrake is the easiest choice if you have never done this before, because it shows you what will happen before the conversion starts.
  • The conversion process takes longer for larger files, but you can close the program and come back later — it will not interrupt.
  • Your original AVI file is never changed or deleted during conversion, so you can keep both versions if you want.

Converting with HandBrake (easiest method)

HandBrake is a free program that works on Windows, Mac, and Linux. Download it from handbrake.fr and install it like any other program. When you open it, you will see a folder icon at the top left — click that and find your AVI file on your computer.

Once you select the file, HandBrake shows you a preview and a list of settings on the right side. Look for the dropdown menu that says "Format" or "Container" near the top of the settings panel. Click it and choose MP4. Leave the other settings as they are unless you have a specific reason to change them. Then click the "Start" button at the bottom. The conversion will begin, and a progress bar will show you how long it will take.

When it finishes, your new MP4 file appears in the same folder as your original AVI. The whole process usually takes 10 to 20 minutes for a standard video.

Converting with VLC media player (if you already have it)

VLC is a video player that most people already have installed. It can also convert files, though the option is hidden in the menu. Open VLC, then click "Media" at the top left and select "Convert / Save" (the exact wording depends on your version).

A window will open with a button that says "Add" or "Open Media." Click it and find your AVI file. Once selected, look for a button labeled "Convert" or "Tools" at the bottom of that same window. Click it, then choose MP4 from the format list. You may see options for video quality — the default settings work fine for most uses. Click "Start" and wait for the conversion to finish.

This method is slower than HandBrake and the interface is less clear, but it works if you already have VLC and do not want to download another program.

Converting with FFmpeg (for command line users)

FFmpeg is a powerful tool that runs from the command line or terminal. It is faster than the other two methods and gives you more control, but it requires typing commands instead of clicking buttons. Download it from ffmpeg.org and follow the installation instructions for your operating system.

Once installed, open your command line or terminal and navigate to the folder where your AVI file is stored. Then type this command and press Enter:

ffmpeg -i yourfile.avi -c:v libx264 -c:a aac yourfile.mp4

Replace "yourfile" with the actual name of your AVI file. The command tells FFmpeg to read the AVI, convert the video using the H.264 codec, convert the audio to AAC format, and save it as MP4. The conversion will start immediately and show a progress bar in the terminal. This method is the fastest of the three and produces the smallest files.

Choosing the right quality settings

All three tools let you adjust video quality before conversion. Higher quality means larger file size and longer conversion time. For most uses — watching on a phone, uploading to social media, or storing on a computer — the default settings are fine.

If your video will be watched on a large screen or projected, you might want to increase the quality. If you need the smallest possible file for email or slow internet, you can lower it. HandBrake shows you an estimated file size before you start, so you can see the trade-off. VLC and FFmpeg do the same if you look for the "bitrate" or "quality" settings in their menus.

What to do if the conversion fails or looks wrong

If the conversion stops with an error message, the most common cause is a corrupted AVI file or a version of the file that your tool does not recognize. Try opening the AVI in a media player first to make sure it plays. If it does not, the file itself may be damaged and conversion may not be possible.

If the conversion finishes but the video looks pixelated, frozen, or has audio that does not match the picture, try converting again with higher quality settings. This usually fixes the problem. If it happens with all three tools, the original AVI file may have been recorded or saved with an unusual codec that needs special handling.

Keeping your files organized after conversion

After conversion, you have both an AVI and an MP4 version of the same video. Decide whether you need to keep the AVI. If the MP4 plays correctly on all your devices, you can delete the AVI to save disk space — it takes up room for no reason. If you want to keep both, move one to a separate folder labeled "Archive" or "Originals" so you do not get confused about which version to use.

If you converted multiple files, rename them clearly so you know which is which. A simple system is to add "-converted" to the end of the filename, so "vacation.avi" becomes "vacation-converted.mp4."

Frequently Asked Questions

Will the video quality get worse when I convert from AVI to MP4?

Not if you use the default settings. MP4 is a more efficient format, so it can store the same quality in a smaller file. You only lose quality if you deliberately lower the settings to make the file smaller. Using the default settings in any of these three tools will preserve the original quality.

How long does conversion take?

A typical 1-hour video takes 10 to 30 minutes to convert, depending on your computer speed and which tool you use. FFmpeg is fastest, HandBrake is in the middle, and VLC is slowest. Larger files take longer. You can close the program and come back later — conversion will continue in the background on most systems.

Can I convert multiple AVI files at once?

HandBrake has a "batch" mode that lets you add multiple files and convert them one after another without watching. VLC and FFmpeg can do this too, but it requires more setup. If you have many files, HandBrake is the easiest choice.

What if my AVI file will not open in any of these tools?

The file may be corrupted or use a codec these tools do not recognize. Try opening it in Windows Media Player or QuickTime first to confirm it plays. If it does not play anywhere, the file is likely damaged and may not be convertible. If it plays in a media player but not in the conversion tool, try downloading the latest version of that tool.

Do I need to delete the original AVI file after converting?

No. Your original AVI stays on your computer and is never touched during conversion. You can keep both files if you want, or delete the AVI later to save space. The choice is yours.