Convert AVI to MP4
Convert AVI to MP4 free in your browser. No upload, no signup, no watermark. Files stay on your device.
drop a .avi file
or click to browse
max 500 MBrelated
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how to convert avi to mp4
Drop your AVI file
Drag your AVI file into the drop zone above, or click the box to pick a file from your computer or phone. The browser reads the file directly — nothing uploads.
Click Convert
The page runs ffmpeg.wasm on your device to decode the Audio Video Interleave and encode it as MPEG-4 Part 14. Most conversions finish in a few seconds; large or codec-heavy files (RAW, video) can take longer.
Download the MP4 file
When the conversion finishes, the MP4 file is ready to download. Save it anywhere on your device.
FAQ
common questions
Why convert AVI to MP4?
AVI is a 1990s container that hasn't kept pace with modern video. Many phones, tablets, and recent smart TVs can't play AVI natively; the format is bulky and lacks features standard in MP4 (proper subtitle support, modern codec compatibility, hardware-accelerated playback). MP4 is the modern universal format that plays on every current device.
Will I lose quality going from AVI to MP4?
Depends on the source codec. AVIs often contain older codecs (DivX, Xvid, MPEG-4 Part 2). When the codec needs re-encoding to fit MP4's constraints (typically H.264), the converter adds a small generational quality loss. If the AVI happens to contain an H.264 stream (rare for old files), the conversion can re-mux losslessly.
Will the MP4 be smaller than the AVI?
Usually yes — often substantially. AVI files from the early 2000s commonly use older codecs that compress less efficiently than modern H.264. Re-encoding to MP4 with H.264 typically halves the file size or better. A 700 MB DivX AVI commonly becomes a 300–400 MB H.264 MP4 at similar visible quality.
What about audio?
AVI audio is often MP3, which transfers to MP4 directly without re-encoding when the converter supports it. Older AVIs sometimes use AC-3 or other codecs that get re-encoded to AAC for MP4. Quality preservation matches the video — re-encoding adds a small generational loss, re-muxing is lossless.
Why is conversion slower for AVI than for MOV / MKV?
Older AVI codecs (DivX, Xvid) typically require full re-encoding because they're not MP4-compatible. Re-encoding video frame by frame is much slower than re-muxing (which just rewraps existing codec streams into a new container). Expect AVI-to-MP4 conversions to take roughly the duration of the video itself, sometimes longer for high-resolution sources.