AVI to MP4
AVI to MP4 for the files you actually have: DivX and Xvid movies, camera MJPEG clips, CCTV exports. Re-encoded to H.264 with AAC sound. Free, no sign-up.
- Free & unlimited
- No sign-up
- Files never uploaded
- No watermark
- Up to 2 GB per file
How to convert AVI to MP4
The first visit downloads the converter (about 32 MB) once. After that it loads from your browser cache.
- 1
Choose the AVI
Drop the .avi file or browse for it. Picking it only reads it: you see its size, duration and resolution, and nothing starts until you press Convert.
- 2
Set quality and size
This page opens in Re-encode. Pick High, Medium or Small file, and leave resolution on Original unless you want 1080p, 720p or 480p. Sizes above the source are greyed out.
- 3
Convert and download
The result screen shows the original and new size next to each other. The MP4 keeps the old file name and is web-optimized, so it starts playing before it has fully loaded. In Fast Copy it also says whether the video had to be re-encoded and how many audio tracks were converted.
What this AVI to MP4 converter changes in the file
Most AVI trouble comes from the codecs inside the file, so Re-encode replaces them instead of just relabeling the file.
New video, not a new label
Xvid, DivX and Motion JPEG are rebuilt as H.264 with x264. That pairing of H.264 and AAC is what phones, browsers and editing apps expect inside an MP4.
Every audio track comes along
In Re-encode each audio track, whether MP3, AC3 or PCM, becomes AAC at 192 kbps. A movie with two language tracks keeps both.
Camcorder lines cleaned up
Interlaced video, common in tape camcorder captures, is deinterlaced automatically on Re-encode, so moving edges don't show comb-like stripes on a laptop screen.
Usually smaller than the AVI
Our 6-second Xvid test clip went from 329 KB to 144 KB and took about 6 seconds. MJPEG sources store every frame as a full JPEG, so they tend to shrink even more.
What is inside your AVI, and what happens to it
AVI is only the wrapper. These are the three kinds of video we see most, and how each mode treats them.
| DivX / Xvid movie | Camera MJPEG clip | H.264 AVI | |
|---|---|---|---|
| Video inside | MPEG-4 Part 2 | Motion JPEG, one photo per frame | H.264 (AVC) |
| Usual audio | MP3 or AC3 | PCM, often mono | MP3, AAC or PCM |
| Typical source | 2000s movie and TV rips | Point-and-shoot cameras of the 2000s | Newer recorders, DVRs, capture software |
| Fast Copy | Copied as is, so devices that refused it still refuse it | Re-encoded to H.264 anyway | Copied untouched when 8-bit 4:2:0, far faster than a re-encode |
| Re-encode (this page's default) | Becomes H.264, plays on far more devices | Becomes H.264, usually much smaller | Becomes H.264 again, slower than copying |
| Best choice | Re-encode | Re-encode | Try Fast Copy first |
AVI files people convert to MP4
Where these AVI files usually come from, and why an MP4 copy helps.
A shelf of DivX and Xvid films
Old movie rips often sit on a backup drive as .avi. Converted one by one, they open in TV and tablet apps that skip AVI entirely.
Clips from a 2000s digital camera
Many compact cameras wrote short MJPEG AVI movies next to the JPEG photos. As H.264 they import into a modern photo library and take far less space.
CCTV and dashcam exports
Security recorders often export incidents as AVI. Converting gives you a file you can email to an insurer or attach to a police report without a special player.
Old screen recordings and tutorials
Screen recorders of the Windows XP era often saved large, lightly compressed AVI files. Re-encoding at Medium makes them practical to upload to a course site.
Tape camcorder captures
Home videos digitized through a capture card are usually interlaced AVI. Re-encode deinterlaces them for smooth playback on today's screens.
Common AVI to MP4 conversion mistakes
Mistake: Renaming movie.avi to movie.mp4.
Do this instead: The player still finds Xvid or MJPEG inside, now under a misleading name. Convert the file so the video itself changes.
Mistake: Hoping the MP4 will look sharper.
Do this instead: Converting can't add detail a 640x480 camera clip never had. Resolution only goes down here, so keep Original and choose High for clips you want to keep.
Mistake: Re-encoding an AVI that already holds H.264.
Do this instead: Switch to Fast Copy for those. The video is copied untouched when it is 8-bit 4:2:0, and the result screen tells you if it had to be re-encoded after all.
Mistake: Leaving the subtitle file behind.
Do this instead: A separate .srt next to the movie is not merged in, because this page reads only the AVI. Keep the .srt beside the MP4 with the same name; players such as VLC load it automatically.
Mistake: Dropping in a capture larger than 2 GB.
Do this instead: Browser memory runs out at about 2 GB per file. Split long captures, or use a desktop tool such as HandBrake for them.
Cost, privacy and limits
Free, as many files as you like
No account, no watermark and no cap on the number of conversions. Files go through one at a time; there is no batch queue.
Your video stays on your computer
Your file is converted on your own device and is never uploaded to our servers. That matters for CCTV footage and family tapes. The only thing downloaded is the converter itself, served by jsDelivr.
About 2 GB per file
The limit comes from browser memory. In our tests a 1.6 GB file converted and a 2.1 GB file stopped with an out-of-memory message.
Plain FFmpeg inside
The engine is FFmpeg 5.1.4 built for WebAssembly, unmodified, so it reads DivX, Xvid and MJPEG streams the way desktop FFmpeg does.