A 50MB podcast export that won't attach to an email; a folder of voice memos eating your storage. "Compress aac" is one of the most-searched audio jobs — but most people hit compress without deciding one thing first: AAC is already a lossy format, so compressing it means re-encoding it. The whole game is minimizing the damage from that second encode.

First, Decide If You Need To

  • Just can't send it? Try a transfer method first (cloud link, messenger file send) and leave the file alone.
  • Need to save space/bandwidth, and won't edit it again? Compress away.
  • Will edit this file later? Keep the original and store the compressed copy separately — every lossy generation compounds.

Picking a Bitrate by Content

AAC quality is mostly a bitrate decision. By content type:

  • Voice-heavy podcasts/recordings: 64–96 kbps is plenty — speech occupies a narrow frequency range, and higher bitrates are inaudible.
  • General music: start at 128 kbps; go 192 kbps if you're picky.
  • Not sure: 128 kbps — the most common balance of size and quality.

Keep the sample rate at the original (usually 44.1kHz) unless you know why you'd change it.

Compressing in the Browser

  1. Open the audio compressor and drop in the AAC file — processed locally, nothing uploaded.
  2. Choose AAC as the output format and set the bitrate from the table above.
  3. After processing, audition 30 seconds: focus on highs (cymbals, breath sounds) for watery artifacts or muddiness.
  4. Happy? Download. Not happy? Raise the bitrate and rerun until size and quality both work.

One Honest Warning

At moderate bitrates, human ears are surprisingly bad at telling compressed from original — but don't ping-pong: recompressing an already-compressed file compounds the damage for real. Keep originals and outputs in separate folders, and always start a new version from the original.

Have an AAC file waiting to slim down? Drop it into the audio compressor — no installs, no uploads.