AVI to MP4 Converter
Convert AVI to MP4 in your browser: DivX and Xvid downloads, MJPEG clips from old digital cameras and AVI exports from Windows software. Browsers cannot read AVI, so ProMedia loads its FFmpeg engine once (about 31 MB), decodes the file on your device and saves H.264 video with AAC audio, the MP4 that phones, Macs and TVs play. Nothing is uploaded.
- Runs on your device
- FFmpeg
- WebCodecs · GPU
- Works offline
Updated
Drop your videos here
How to convert AVI to MP4
Step 1: Drop your AVI files on the box above, or tap it to choose them.
Step 2: The first time, the FFmpeg engine downloads (about 31 MB) and is cached for later visits.
Step 3: Keep Quality on Balanced, or pick Best quality for footage you plan to edit.
Step 4: Press Convert and download the MP4 files.
Good to know
Settings explained
- Quality
- Only used when a stream has to be re-encoded. Compatible streams are copied with no quality loss.
- Faster: Smaller file, quickest export
- Balanced: Good quality at a sensible size
- Best quality: Largest file, slowest export
- Video codec
- Automatic copies the original video stream when the new format can hold it, so there is no quality loss.
- Automatic: Best codec the format and your device support
- H.264 (AVC): Plays everywhere
- H.265 (HEVC): About 35% smaller, newer devices
- VP9: Web / WebM
- AV1: Smallest files, slowest to encode
- Always re-encode
- Off: compatible streams are copied instantly and losslessly. On: every stream is re-encoded, which can fix playback glitches.
Formats
Batch-friendly: add many files and they are processed one after another — if one fails, the rest still finish.
How it runs
- FFmpeg (when needed)
- Older formats and a few filters use FFmpeg compiled to WebAssembly. It downloads once (about 31 MB) the first time it is needed and is cached for offline use.
- Hardware video engine
- Video is decoded and encoded by your device’s media hardware through WebCodecs — usually several times faster than real time.
AVI vs MP4: which is better?
MP4 is the better choice for almost every use today. AVI dates from 1992 and was designed for Windows: it stores older codecs well but handles modern compression, streaming and subtitles poorly, and phones, Macs and smart TVs often refuse it. MP4 with H.264 plays everywhere and is usually smaller for the same picture.
| Feature | AVI (Audio Video Interleave) | MP4 (MPEG-4 Part 14) |
|---|---|---|
| Introduced | 1992, Microsoft Video for Windows | 2003, ISO standard |
| Typical video | DivX or Xvid (MPEG-4 Part 2), MJPEG, sometimes H.264 | H.264, HEVC, AV1 |
| Typical audio | MP3, PCM, AC-3 | AAC |
| Plays on iPhone, Mac and most TVs | Rarely | Yes |
| Size for the same picture | Larger with Xvid, much larger with MJPEG | Smaller with H.264 |
| Starts playing before it fully downloads | Poorly | Yes (ProMedia writes the index at the front) |
What is an AVI file?
An AVI file (Audio Video Interleave) is Microsoft’s video container from the Windows 3.1 era. Inside you usually find MPEG-4 Part 2 video made by DivX or Xvid, Motion JPEG from digital cameras and webcams, or occasionally H.264, paired with MP3, PCM or AC-3 audio.
The container is simple and sturdy, which is why camera makers used it for years. It never gained good support beyond Windows, though, and modern phones and browsers do not open it.
Does converting AVI to MP4 lose quality?
Usually only a little. DivX, Xvid and MJPEG cannot live in an MP4, so they are re-encoded to H.264 with the x264 encoder at a constant-quality setting: the bitrate follows the picture rather than a fixed number, and at Balanced or Best quality the change is hard to spot. AVIs that already hold H.264 are copied without any loss.
| What is in the AVI | What happens | Quality |
|---|---|---|
| DivX or Xvid (MPEG-4 Part 2) video | Re-encoded to H.264 | Near-identical at Balanced or Best |
| MJPEG from a camera or webcam | Re-encoded to H.264 | Near-identical; the file is usually far smaller |
| H.264 video | Copied as-is | Identical |
| MP3, PCM or AC-3 audio | Converted to AAC at 128 kbps (adjustable) | Clean for speech and most music |
Can you rename AVI to MP4?
No. AVI and MP4 are built differently, and the DivX or Xvid video inside is not something most MP4 players decode, so a renamed file just fails to open. Converting rewrites the container and, where needed, the video itself.
Why convert AVI to MP4 with ProMedia
- Big files, honestly. There is no upload, so there is no upload cap. The FFmpeg engine builds the MP4 in your browser’s memory, so files up to about 2 GB work on a computer; on an iPhone, stay under about 250 MB.
- Works on a Chromebook. It is a web page, so ChromeOS, Windows, macOS and Linux run the same converter with nothing to install.
- Home videos stay home. Old family recordings are decoded on your own machine and never sent to a server.
- Offline after the first run. Once the engine is cached, the converter works without an internet connection.
Convert AVI to MP4 on Windows 11, Mac, iPhone or Android
Windows 11
Drag AVI files from File Explorer into Edge or Chrome. Windows plays many AVIs itself, but the people you send them to may not; the MP4 copy plays on their phones too.
Mac
QuickTime cannot open DivX or Xvid AVIs. Drop them into Safari or Chrome here and the MP4 opens in QuickTime, Photos and iMovie.
iPhone
Save the AVI to Files, open this page in Safari and tap the drop zone. Large files are better done on a computer, because the FFmpeg engine needs memory.
Android
In Chrome, tap the drop zone and pick the AVI from Downloads. The MP4 is saved to Downloads and appears in your gallery.
Tips & troubleshooting
Conversion fails, or the AVI will not open anywhere? Try repair video first; it rebuilds damaged indexes and timestamps.
Old camera clips are often grainy. After converting, denoise video can clean up the noise.
Need the MP4 under an upload or email limit? Follow up with the video compressor.
Converting a folder of clips? Drop them all at once; they run one after another and you can download a single ZIP.
AVI to MP4 Converter FAQ
How do I convert AVI to MP4 without losing quality?
If the AVI holds H.264, it is copied and nothing is lost. Otherwise choose Best quality, which uses x264 at CRF 23, and keep the original resolution. The re-encode then keeps nearly all visible detail, and the MP4 is often smaller than the AVI because H.264 is more efficient than DivX, Xvid or MJPEG.
Should I convert AVI to MP4?
Yes, if the video should play on phones, Macs, TVs or the web, or open in modern editing apps. If it is a family archive, keep the original AVI as well: converting costs a little quality, and you may want to redo it later with other settings.
Why does this tool download an engine?
Browsers have no AVI reader or DivX decoder built in, so ProMedia loads FFmpeg compiled to WebAssembly, about 31 MB. It downloads once from this site, is cached by your browser and runs entirely on your device.
How long does AVI to MP4 take?
FFmpeg runs on your processor rather than the graphics chip, so it is slower than the hardware path used for MKV or MOV. Short clips take moments, long ones a few minutes, and phones are slower than laptops.
How do I convert AVI to MP4 on a Chromebook?
Open this page in Chrome, click the drop zone and pick the AVI from the Files app. The FFmpeg engine runs inside Chrome, so nothing needs installing, and the MP4 is saved to your Downloads folder.
Is your video uploaded anywhere?
No. Your video is processed by your own browser on your own device. There is no server that receives files, so nothing is uploaded, stored or shared. You can even switch to airplane mode once the page has loaded.