AVI Compressor

How to Compress AVI Files Online

1. Upload Your AVI Files: Drag and drop or click "+ Add Files" to select AVI clips from your computer. Batch upload is supported — every file uses the same settings.
2. Pick a Compression Method: Open Advanced Options and choose one of six modes — Target file size (%), Specific file size (MB), Constant Bitrate, Variable Bitrate, Constant Quality (CRF), or Constraint Quality. Defaults to Target file size (%) at 80, which is usually the safest first pass for legacy footage.
3. Resize, Trim, or Re-encode (Optional): Pick a resolution preset (2160p down to 144p), scale by percentage, or set custom width/height. Use Trim → Time Range to drop unused leader/trailer. To keep the .avi extension change Video Codec under Advanced Options (Xvid, DivX, MPEG-4, MJPEG, H.264, MPEG-2, FLV, Theora). Leave Auto Scale on to keep aspect ratio.
4. Compress and Download: Click "Compress". Files process in your browser session — no sign-up, no watermark, no quality cap pushed behind a paywall.

Why Compress AVI?

AVI (Audio Video Interleave) is Microsoft's RIFF-based container, first shipped with Video for Windows in November 1992. Two things make AVI files unusually large today: the container itself has more per-frame overhead than MP4 or MKV, and the codecs commonly bundled inside it — Xvid, DivX, MPEG-4 Part 2 (both released around 2001), MJPEG, and uncompressed RGB — are 2-3x less efficient than modern H.264 or H.265. Shrinking AVI is mostly about routing the same pixels through a smarter encoder, optionally trimming dead footage, and dropping resolution where it won't be missed.

• Old camcorder transfers — MiniDV and Hi8 captures land as AVI at 13-25 Mbps. A 1-hour tape can run 11-25 GB on disk; re-encoding to H.264 at the same visual quality typically lands at 1.5-3 GB.
• Screen recordings from older capture tools — Camtasia, OBS legacy presets, and Bandicam often default to AVI with MJPEG or uncompressed output. Compressing to a CRF-based codec cuts size by 80-95% with no perceptual loss for static UI footage.
• Email and chat attachments — Gmail caps inline attachments at 25 MB, Outlook.com at 20 MB, and Discord's free tier at 10 MB (lowered from 25 MB in September 2024). A 2-minute AVI clip almost always needs compression before it goes in any message.
• Archive consolidation — A drive of legacy AVI files from 2005-2012 can shrink 60-80% by re-encoding to H.264 inside the same AVI container, with the original bit-for-bit playable on the same software that opened the originals.
• Editing pipelines that still want AVI — Some Windows-era NLEs (VirtualDub, older Premiere projects, AviSynth scripts) only handle AVI cleanly. Re-encoding to Xvid or MPEG-4 at a lower bitrate keeps compatibility while reducing footprint.
• Older devices and players — Standalone DVD players, in-flight entertainment systems, and certain media boxes from the 2000s often play AVI only. Compress in place rather than converting, then sideload.

AVI Codec Efficiency Comparison

These figures are typical for 1080p at "watchable web" quality; exact numbers depend on motion complexity and your CRF/bitrate target.

Compress in AVI vs Convert to MP4 — Decision Guide

CRF Quick Reference

CRF (Constant Rate Factor) targets a constant perceptual quality and lets the encoder pick the bitrate frame by frame. Lower CRF = higher quality and larger files.

A rule of thumb: H.265 CRF roughly equals H.264 CRF + 4 at similar perceived quality, and produces files ~40-50% smaller.

Frequently Asked Questions

Why is my AVI so much larger than an MP4 of the same video?

Two reasons stack. First, AVI's container overhead is higher than MP4's — index tables and per-chunk headers cost more bytes per second. Second, AVI files are usually encoded with Xvid, DivX, or MPEG-4 Part 2, which are roughly half as efficient as H.264 and a third as efficient as H.265 at equal visual quality. Re-encoding the same source to H.264 inside an MP4 container typically cuts size by 50-70%.

Should I compress in AVI or just convert to MP4?

If any downstream tool (legacy editor, hardware DVD player, AviSynth script) specifically requires .avi, compress in AVI. Otherwise convert to MP4 with H.264 — you'll get a smaller file, broader playback support, and proper B-frame compression. AVI's spec doesn't reliably handle B-frames, which is one reason it can't match MP4 efficiency even with the same codec.

Will compression damage the original file?

No. Your source file is never modified. Compression produces a new output file; the original AVI sits on your disk untouched. If the new file looks worse than you want, re-run with a higher quality setting (lower CRF or higher target size %).

What CRF should I pick for AVI compression?

If you're keeping H.264 inside AVI, start at CRF 20-22 — that's slightly above default and gives meaningful savings without visible artifacts. For Xvid the equivalent is qscale 4-5. Drop CRF (or qscale) by 2 if you see blockiness on dark gradients or fast motion; raise it by 2 if you need a much smaller file and the content is mostly static.

My AVI is from a MiniDV camcorder — what settings work best?

DV-AVI runs 13 Mbps interlaced 720x480 (NTSC) or 720x576 (PAL). De-interlace during compression if your encoder supports it, then target H.264 CRF 20 at the original resolution. A 60-minute tape (13 GB) typically lands at 1-1.5 GB with no perceptible quality loss. Many users move to MP4 at this point — see Convert AVI to MP4.

Can I compress without re-encoding the video?

Partially. If you only need to trim length, use Trim AVI — it does a stream copy with no quality loss. To shrink the file without trimming you must re-encode; AVI has no other "lossless shrink" path because it doesn't support modern features like B-frames that more efficient codecs rely on.

Does this tool support AVI with MJPEG, Xvid, DivX, or uncompressed RGB?

Yes. The compressor accepts AVI files regardless of which codec is inside — Xvid, DivX, MPEG-4 Part 2, MJPEG, MS-MPEG4 (Microsoft's WMV variants inside AVI), HuffYUV, and uncompressed RGB are all supported. You can keep the source codec or switch to a more efficient one in Advanced Options → Video Codec.

Will subtitles or chapter markers survive?

AVI's specification doesn't support attached subtitles, embedded fonts, or chapter markers — those have to live in a sidecar .srt file or be hardcoded into the video stream. If your AVI was made with hardcoded subtitles, they'll remain (they're pixels in the video). For a container that does carry soft subtitles natively, compress into MKV instead via Convert AVI to MKV.

Are there file size or count limits?

Files process in your browser session, so the practical ceiling is your device's available RAM and storage. There's no per-file watermark, no sign-up requirement, and no daily count cap on this page.