How to Convert AVI to MP4 on Windows & Mac
Updated August 31, 2026
AVI is where old videos live: camcorder footage, early digital cameras, files burned to DVDs and forgotten. Modern phones, TVs, and editors treat AVI with suspicion when they open it at all. Converting to MP4 brings those videos into the present.
This guide uses ConvertSave on Windows and Mac. Everything converts locally and offline, which suits irreplaceable family footage particularly well.
How to convert AVI to MP4
- 1
Drag your files into ConvertSave
Open ConvertSave and drag your AVI files into the window. You can drop one file or a whole selection at once. There is no upload step, because the files never leave your computer.
- 2
Choose MP4 as the output format
Pick MP4 from the format list. ConvertSave shows the formats that make sense for the files you dropped, so MP4 is right there.
- 3
Click Convert
Hit the Convert button. Each MP4 file is saved next to the original, so you don't have to hunt through folders to find your converted files. The originals are left untouched.
Only need the sound? AVI to MP3
Pick MP3 instead of MP4 and the audio track comes out on its own; WAV, M4A, and FLAC work too. Handy for old concert or interview footage where the sound is the part worth keeping.
How to batch convert AVI to MP4
Digitized archives arrive by the folder, so queue the whole folder: drag it in, pick MP4 once, convert. Each MP4 is saved next to its AVI and the originals aren't touched, so your archive stays intact. We've tested batches of up to a thousand files.
Going the other way: MP4 to AVI
Occasionally old software or hardware demands AVI. Same steps with AVI as the output, and it accepts MOV, MKV, and WEBM sources as well.
AVI vs MP4: what's the difference?
| AVI | MP4 | |
|---|---|---|
| Era | 1992, Windows heyday | Modern standard |
| Plays on | Older Windows software, some players | Effectively everything |
| File size | Usually larger for the same quality | Smaller |
| Best for | Legacy workflows | Watching, sharing, editing today |
Is AVI to MP4 conversion safe?
The risk with converting old AVI videos isn't the conversion itself, it's where the conversion happens. Free converter websites work by uploading your file to someone else's server. You usually can't tell who runs the server, where it is, or how long your file sticks around after the conversion finishes. For personal videos and photos that's a real privacy trade, and it's the reason so many of those sites are covered in aggressive ads.
ConvertSave does the conversion on your own computer. Nothing is uploaded anywhere. You can turn off Wi-Fi entirely and it still works, which is also the easy way to verify the claim. Your original file is never modified, and the converted copy is written right next to it.
Frequently asked questions
Will converting old AVI files lose quality?
The conversion re-encodes with modern compression at settings chosen to preserve how the video looks. Old AVI footage is usually low resolution to begin with; the MP4 will look the same and take less space. Your original AVI stays untouched either way.
My AVI won't play at all. Will conversion still work?
Usually yes. Playback requires your player to support the AVI's internal codec, but ConvertSave's conversion engines read far more codecs than most players do.
Can I convert a whole folder of old videos at once?
Yes. Drag the folder's contents in and convert them as one batch. We've tested up to a thousand files.
Do my videos get uploaded anywhere?
No. ConvertSave converts on your computer and works offline. Family footage stays home.
Is ConvertSave free?
There's a 7-day free trial with all features unlocked. After that it's $9/month, $60/year, or $129 once for a lifetime license that covers 3 personal devices on Mac and Windows.
