AVI to MP4 Converter

How to Convert AVI to MP4 Online

1. Upload Your AVI File: Click "+ Add Files" or drag your AVI clip into the drop zone. Multiple files at once are fine — they all share the settings you pick below.
2. Pick a Quality Preset (or Constant Bitrate / Constant Quality): Default is Very High (Recommended), which produces a universally compatible H.264 MP4. Switch to Constant Quality and lower CRF (0-51) for archival-grade output, or Specific file size to hit a target like 100 MB for email/upload caps. The audio is re-encoded to AAC by default; pick a different audio codec under Advanced Options if you need AC-3 surround.
3. Resolution and Trim (Optional): Keep original, scale by Resolution Percentage, choose a Preset Resolution (240p through 4K UHD / 2160p), or enter a custom Width x Height. Under Trim, switch from Unchanged to Time Range to clip a section in HH:MM:SS.mmm format.
4. Convert and Download: Click "Convert" and the file processes on our servers — no sign-up, no watermark, runs on xconvert’s servers with no per-file cap. Downloaded MP4s use the broadly compatible H.264 + AAC combination unless you changed it.

Why Convert AVI to MP4?

AVI is a Microsoft container introduced in November 1992 as part of Video for Windows, built on the RIFF specification that Microsoft and IBM published in 1991. MP4 (formally ISO/IEC 14496-14:2003) is the modern ISO Base Media File Format derivative used by virtually every camera, phone, browser, and streaming platform shipped in the last decade. Re-muxing or re-encoding an AVI to MP4 trades a 30+ year old container for one that handles modern codecs, streaming-friendly indexing, soft subtitles, and chapters.

• Universal playback — iOS and Android do not play AVI natively. Safari, Chrome's <video> tag, Quick Look on macOS, the Photos app on iPhone, and most smart TVs reject AVI; MP4 with H.264 + AAC plays everywhere a video tag is supported.
• Smaller files at the same quality — Many AVI files in the wild use older codecs (DivX, Xvid, MS MPEG-4, MJPEG) at high bitrates. Re-encoding to H.264 typically shaves 30-60% off the file size for the same perceived quality; H.265/HEVC cuts another 25-50% on top of that.
• Streaming and uploads — YouTube, Instagram Reels, TikTok, X, LinkedIn, and Facebook all document MP4/H.264 in their recommended upload specs. AVI uploads are either rejected outright or re-transcoded server-side with extra quality loss.
• Soft subtitles and chapters — AVI's container cannot cleanly carry SRT or AAC. MP4 supports embedded mov_text subtitles, multiple audio tracks, and chapter markers, so a single file can ship dubs and captions together.
• Legacy archive recovery — Old DV camcorder dumps, 2000s-era DivX rips, and screen recordings saved as AVI are increasingly orphaned by modern devices. MP4 makes them future-proof without re-shooting.
• Editor and NLE compatibility — Final Cut Pro does not import AVI at all. DaVinci Resolve, Adobe Premiere, and CapCut prefer MP4/MOV with H.264 or ProRes. Converting first avoids "unsupported format" errors mid-edit.

AVI vs MP4 Container Comparison

AVI Source Codec Compatibility Cheat Sheet

Frequently Asked Questions

Does converting AVI to MP4 lose visual quality?

Any time you re-encode from one lossy codec to another (Xvid to H.264, for example) you incur some generational loss, but at the default Very High preset the difference is generally imperceptible. If you want zero perceptual loss, switch to Constant Quality and set CRF to 17-18; the result will be visually indistinguishable from the source while still being substantially smaller than the AVI.

Can I remux AVI to MP4 without re-encoding?

Usually no. Most AVI files use DivX/Xvid/MPEG-4 ASP or MJPEG, which the MP4 container does not accept verbatim — the codec has to be transcoded. In rare cases where the AVI already holds H.264, AVI's index format still doesn't cleanly support B-frames or VFR, so a clean remux often fails. The safest path is a single quality re-encode to H.264 or H.265.

Should I pick H.264 or H.265 (HEVC) for the output?

H.264 if you want it to play everywhere by default — every browser, every iPhone since 2010, every Android device, every smart TV. H.265 if file size matters more than reach: it cuts size 25-50% further, but Firefox on desktop still does not decode HEVC, and some older Android devices struggle. For compressing the MP4 further after conversion, H.265 is the better re-encode target.

Will the audio be preserved?

Yes. Both video and audio tracks are converted. The audio is re-encoded to AAC by default — the standard MP4 audio codec, more efficient than the MP3 or PCM commonly found in AVI. If your AVI has 5.1 AC-3 audio (common on DVD rips), pick AC-3 in the audio codec dropdown to keep the surround layout instead of folding it to stereo AAC.

My AVI file uses DivX or Xvid — will it work?

Yes. XConvert decodes all common AVI video codecs including DivX 3-6, Xvid, Microsoft MPEG-4 v1/v2/v3, MJPEG, HuffYUV, and uncompressed YUV/RGB. The source codec is detected automatically; you just pick the output quality.

My MP4 is much bigger than my original AVI — why?

The output bitrate exceeds the source. AVI files using highly compressed Xvid at low bitrates can be smaller than a re-encode at the default Very High preset. Either lower the quality preset, switch to Constant Quality with a higher CRF (28-32), use Specific file size to target a percentage of the source, or once the MP4 is saved you can compress the video down to a target size.

Can I trim the AVI while converting?

Yes. Under the Trim section switch from Unchanged to Time Range and enter start/end timestamps in HH:MM:SS.mmm format. For dedicated cut-only work without re-encoding the whole timeline, the video cutter tool is faster.

Are my files uploaded to a server?

The Conversion runs on our servers. Files are not retained after you close the tab and there is no account or sign-up required. There's also no watermark, file count limit, or paid tier for AVI to MP4 conversions.

What about MP4 to AVI in reverse?

If you need the opposite direction — sending a clip to legacy Windows software that only reads AVI — use MP4 to AVI. For other container moves see AVI to MKV (open-source container, better for archival) or MKV to MP4 (mobile-friendly output).