The fastest way to convert AVI to MP4

The simplest route is to use VLC Media Player, which is free and works on Windows, Mac, and Linux. Open VLC, go to Media > Convert/Save, select your AVI file, choose MP4 from the profile dropdown, and click Convert. The file saves to your Videos folder by default. The whole process takes a few minutes depending on file size.

If you have many files to convert or want more control over quality settings, HandBrake is the next step up. It's also free, lets you batch-convert multiple files at once, and gives you options for video quality, frame rate, and audio codec. read it, drag your AVI file into the window, select MP4 as the format, and click Start.

Windows users with Windows 10 or 11 can also use the built-in Photos app: open the AVI file, click the three dots menu, select Edit, then Export as > MP4. This works for quick conversions but offers fewer customization options than VLC or HandBrake.

Key Takeaways

  • VLC Media Player converts AVI to MP4 in three steps and works on any operating system without installing additional software.
  • HandBrake is better if you're converting many files at once or need to adjust video quality, frame rate, or audio settings.
  • The conversion process creates a new MP4 file and leaves your original AVI file untouched.
  • File size and your computer's processor speed determine how long conversion takes, typically from a few minutes to an hour for large files.

Understanding what happens during conversion

When you convert AVI to MP4, you're not just changing the file extension. AVI and MP4 are containers — they hold video, audio, and subtitle data in different ways. Conversion reads the video and audio from your AVI file and re-encodes it into the MP4 container format.

This re-encoding is why conversion takes time. Your computer has to decompress the video data, process it, and compress it again in the new format. The quality of the output depends on the bitrate you choose — higher bitrate means larger file size but better quality. Most converters use sensible defaults that balance quality and file size.

The original AVI file stays on your computer unchanged. The converter creates a brand-new MP4 file, so you can delete the AVI afterward if you want to save space.

Why you might need to convert AVI files

AVI files were common in the 1990s and 2000s but are rarely used now. Most phones, tablets, and streaming services expect MP4 format. If you have old video files from a camcorder or downloaded from the internet years ago, they're likely AVI.

MP4 is smaller, plays on almost any device, and uploads faster to cloud storage or video platforms. Converting old AVI files to MP4 makes them usable on modern devices without hunting for special software.

Using VLC step by step

read VLC Media Player from videolan.org if you don't have it. Open the process and click Media in the top menu. Select Convert/Save from the dropdown.

Click the Add button and navigate to your AVI file. Select it and click Open. Back in the Convert window, click the dropdown next to Profile and search for "MP4". Select Video - H.264 + MP3 (MP4) or a similar MP4 option.

Click Browse to choose where you want the MP4 file saved. The default location is your Videos folder. Type a name for the new file if you want to change it from the original. Click Convert and wait for the progress bar to finish.

Using HandBrake for batch conversion

read HandBrake from handbrake.fr. Open it and click the Source button to select your AVI file. You can also drag and drop the file directly into the window.

On the right side, make sure the format is set to MP4. Leave the preset on Fast 1080p30 unless you need different quality settings. If you're converting multiple files, click Add to Queue and repeat the process for each file. HandBrake will convert them one after another.

Click Start Encode and let it run. HandBrake shows a progress bar and estimates how long each file will take. When finished, your MP4 files appear in the folder you selected.

Adjusting quality and file size

If your converted MP4 file is too large, you can reduce the bitrate. In VLC, click the Tools menu, select Preferences, go to Input/Codecs, and look for the Video codec settings. In HandBrake, use the Quality slider — moving it left makes smaller files but lower quality, moving it right makes larger files with better quality.

For most purposes, the default settings work fine. Only adjust these if you're running out of storage space or uploading to a platform with file size limits. Test with one file first before converting a whole batch with custom settings.

Frame rate affects both file size and smoothness. Most videos are 30 frames per second. Lowering it to 24 fps saves space but may look slightly less smooth. Raising it above 30 fps makes larger files without noticeable quality improvement for most content.

Troubleshooting common problems

If VLC or HandBrake won't open your AVI file, the file may be corrupted or use an unusual codec. Try opening it in VLC first — if VLC can play it, the file is readable and conversion should work. If VLC can't play it, the file itself may be damaged.

If conversion starts but stops partway through, your hard drive may be full. Check that you have at least as much free space as the AVI file size. Close other programs to free up memory, especially if your computer is older.

If the converted MP4 plays but has no sound, the audio codec wasn't recognized. Try converting again and manually select a different audio codec from the options menu. MP3 audio works on virtually all devices.

Frequently Asked Questions

Will converting AVI to MP4 reduce video quality?

Some quality loss happens because both formats use compression, but it's usually not noticeable unless you zoom in or look very closely. Using the default quality settings in VLC or HandBrake preserves enough detail for watching on phones, tablets, and computers. If quality matters for your use, test the conversion on a short clip first.

How long does it take to convert a file?

A typical 1 GB video file takes 5 to 15 minutes on a modern computer. Older computers or very large files may take an hour or more. The speed depends on your processor, how much RAM you have, and what else your computer is doing. Closing other programs speeds up conversion.

Can I convert MP4 back to AVI?

Yes, using the same tools. VLC and HandBrake work in both directions. Open the MP4 file, select AVI as the output format, and convert. However, there's no reason to do this — MP4 is better for modern devices. Keep the MP4 version and delete the AVI.

What if my AVI file is very large?

Make sure you have free hard drive space equal to at least the AVI file size plus the expected MP4 size. A 4 GB AVI file might convert to a 1 to 2 GB MP4 file, so you need at least 6 GB free. If space is tight, convert to an external hard drive or delete other files first.

Do I need special software or can I use an online converter?

Online converters exist but require uploading your file to a website, which takes time for large files and raises privacy concerns. VLC and HandBrake are free, work offline on your own computer, and are faster for files over 500 MB. Use them instead unless you have a specific reason to use a web-based tool.