AVI vs MP4: Differences and Which Video Format to Use

Use MP4. AVI is a Microsoft container first specified in 1992, built on the RIFF format, and the Library of Congress notes it was not designed for codecs that reference future frames, which modern codecs such as H.264 rely on. MP4 (ISO/IEC 14496-14) holds H.264, HEVC and AV1 with AAC audio, plays in every major browser and phone, and is what platforms expect.

More on this topic: Video formats, codecs and numbers, every guide in one place.

Below: a side-by-side table, why AVI files are often bigger, what plays where, and how to convert AVI to MP4, losslessly where possible.

The short answer

MP4 is the better choice for almost everything: sharing, uploading, websites and phones. AVI only makes sense when an old Windows program, a capture device or an archive workflow asks for it. AVI and MP4 are containers, so file size and quality come from the codec inside: an AVI holding uncompressed or DV video is huge, while the same H.264 video in either container is about the same size.

Key takeaways

Both are containers; the codec inside decides quality and size.
AVI dates from 1992 (Windows 3.1); MP4's current spec is ISO/IEC 14496-14:2003.
Original AVI files were capped at 2 GB; the OpenDML (AVI 2.0) extension lifts that limit.
MP4 plays in every major browser; MDN notes that not every container, AVI included, is broadly supported by browsers.
Convert AVI to MP4 with FFmpeg: remux with -c copy when the codecs are MP4-friendly, otherwise re-encode to H.264.

What is the difference between AVI and MP4?

The difference between AVI and MP4 is age and design. AVI (Audio Video Interleaved) is Microsoft's RIFF-based container, which the Library of Congress says was first specified in 1992 and introduced with Windows 3.1. MP4 is the MPEG-4 Part 14 container, standardised as ISO/IEC 14496-14:2003, and built on the same box structure as Apple's QuickTime format.

	AVI	MP4
Full name	Audio Video Interleaved	MPEG-4 Part 14
Origin	Microsoft, 1992 (Windows 3.1)	MPEG, ISO/IEC 14496-14:2003
Structure	RIFF chunks: hdrl (headers), movi (data), idx1 (index)	ISO base media file format boxes
Typical video codecs	Uncompressed, DV, MJPEG, DivX/Xvid, Cinepak, Indeo	H.264, HEVC, AV1
Typical audio	PCM (WAVE), MP3	AAC (also others)
Modern codecs that use B-frames	Possible through workarounds; may cause playback problems	Designed for them
Subtitles	No standard track	Timed text (MPEG-4 Part 17); SRT often kept as a sidecar file
Streaming	Poor	Built for it (fast start, fragmented MP4)
Browser playback	Not broadly supported	All major browsers
Max file size	2 GB for original AVI; far larger with OpenDML (AVI 2.0)	No 2 GB cap

Checked on 26 October 2026 against Microsoft Learn's AVI RIFF reference, the Library of Congress format descriptions for AVI and MP4, and MDN's container guide.

Is AVI better quality than MP4?

AVI isn't better quality than MP4 in itself, because quality comes from the codec and bitrate, not the container. An AVI often looks better only because it holds uncompressed, DV or MJPEG video at a very high bitrate; the same footage in MP4 with H.264 at a sensible bitrate looks the same to most viewers at a fraction of the size.

The Library of Congress lists some real weaknesses of AVI as a format: no standard way to store aspect ratio, competing approaches to timecode, unreliable variable-bitrate audio such as MP3 below 32 kHz, and no reliable flag for interlaced versus progressive video. None of those touch picture quality directly, but they explain why AVI files sometimes play stretched, out of sync or combed.

Why are AVI files bigger than MP4?

AVI files are usually bigger because of the codec inside, not the container. Older capture software and cameras write AVI with lightly compressed or uncompressed video. Rough sizes per minute show the gap (arithmetic: Mbps × 60 ÷ 8):

What's inside	Typical data rate	Per minute
Uncompressed 1080p30, 8-bit 4:2:0	About 746 Mbps	About 5.6 GB
Uncompressed 4K UHD 30p, 8-bit 4:2:0	About 2,986 Mbps	About 22.4 GB
H.264 1080p30 in MP4 (YouTube's recommendation)	8 Mbps	About 61 MB with 128 kbps audio

If both files hold the same H.264 stream, AVI and MP4 differ by only a small amount of container overhead. More numbers are in how big a 1-minute video is.

Does AVI play on iPhone, Android, Mac and browsers?

AVI doesn't play reliably on phones, Macs or in browsers; MP4 does. MDN's container guide names MP4 and WebM as the most common web containers and notes that formats such as AVI aren't broadly supported by browsers. Android's supported media formats page lists MP4 and Matroska (MKV) as the containers for HEVC and AV1, and Apple's apps are built around MP4 and MOV.

Where	AVI	MP4
Web browsers	Not broadly supported (MDN)	Supported in all major browsers (H.264; HEVC and AV1 vary)
Android	Not among the containers Android lists for HEVC or AV1	Listed container for HEVC and AV1
iPhone, iPad and Mac apps	Often won't open without a third-party player	Plays
Windows	AVI is Microsoft's own format; plays when the codec is installed	Plays
VLC (any computer or phone)	Plays	Plays

If someone sends you an AVI that won't open, VLC is the quickest way to watch it; converting is the way to share it.

Can you upload AVI to YouTube and social media?

YouTube accepts AVI: it's on YouTube's list of supported file formats, along with MOV, MP4, WebM and others. But YouTube's recommended upload settings specify H.264 in an MP4, and most social apps expect MP4 or MOV, so convert AVI before uploading anywhere else. Platform specifics are in MP4 vs MOV.

How do you convert AVI to MP4?

You convert AVI to MP4 by remuxing it when the codecs inside are MP4-friendly, or by re-encoding it when they aren't. First check what's inside with ffprobe in.avi (or VLC's Tools > Codec Information).

If the video is H.264 and the audio is AAC or MP3: remux without quality loss in seconds: ffmpeg -i in.avi -c copy out.mp4.
If it's DivX/Xvid, MJPEG, DV or uncompressed: re-encode to H.264: ffmpeg -i in.avi -c:v libx264 -crf 20 -preset medium -pix_fmt yuv420p -c:a aac -b:a 192k out.mp4.
If the video looks combed (interlaced DV): add a deinterlace filter: -vf yadif before the output name.
If the picture is stretched: AVI may have lost the aspect ratio; set it with -aspect 16:9 (or 4:3).

HandBrake does the re-encode with a preset if you prefer an app. The free video compressor only opens videos your browser can play, so it won't read most AVI files; convert to MP4 first, then use it to shrink the file for email or chat. It's free, runs in your browser and never uploads your file.

When should you still use AVI?

Use AVI only when a tool or workflow requires it:

Older Windows capture cards, scientific cameras or lab software that only write or read AVI.
Legacy editing pipelines built around DV-AVI or MJPEG-AVI.
Archives already stored as AVI, where the Library of Congress notes OpenDML (AVI 2.0) is what most modern AVI files use.

For everything else, export MP4. If you're choosing between modern containers, MKV vs MP4 and what a WebM file is cover the other two you'll meet.

Frequently asked questions

Is AVI or MP4 better?

MP4 for almost every use: it's smaller with modern codecs, plays everywhere and suits uploads. AVI only for legacy tools that need it.

Is AVI higher quality than MP4?

Not by itself. Quality comes from the codec and bitrate; AVIs often hold less-compressed video, which is why they're bigger.

Does converting AVI to MP4 lose quality?

Not if you remux (ffmpeg -c copy) H.264 video. Re-encoding DivX, MJPEG or DV to H.264 loses a little; use CRF 18 to 20.

Why won't my AVI play on my iPhone or Mac?

Apple's apps don't support most AVI codecs. Play it in VLC or convert it to MP4.

Is AVI still used?

Yes, by some capture devices, scientific and legacy Windows software, and archives. Consumer devices and platforms have moved to MP4.

What is the AVI file size limit?

Original AVI files were limited to 2 GB (1 GB in the earliest versions). The OpenDML extension, also called AVI 2.0, removes that limit.

Try it with your own video

Once your AVI is converted to MP4, QuickVeed can add captions, translate them or dub the video. Upload an MP4 or MOV, check the transcript, and download captions or a captioned copy. QuickVeed plans start at $18/month, and new accounts get a 14-day trial with 250 credits, no card needed. Sign up or see pricing.

Sources

Competitor details in this post were checked against these public pages in October 2026. Products and prices change, so confirm with each vendor before you decide.

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AVI vs MP4: Which Format Should You Use?