Free PDF or media tool

Audio Compressor

Choose an audio file and a bitrate. Your browser re encodes it and gives a smaller file. It takes about as long as the audio plays.

Please note: Compression runs while the audio plays, so a 10 minute file takes about 10 minutes. Keep this tab open. Use Chrome or Edge on a computer for the best result.

By iToolsLab Editorial TeamUpdated 14 October 2026How we build tools

What is audio compressor?

Voice notes, interviews, lectures and podcasts can take a lot of space. For speech, a low bitrate sounds fine and the file becomes much smaller.

This tool records your audio again at the bitrate you choose using your browser's own encoder, so nothing is uploaded and no software is needed.

How to use the audio compressor

  1. Choose your audio file.
  2. Pick a quality level. Use 64 kbps for speech and 128 kbps for music.
  3. Press Compress audio, keep the tab open and download the result.

How the audio compressor works

The audio is played in a hidden player and recorded with the Opus codec at the chosen bitrate. The size of the result is about bitrate times length, divided by eight.

Worked example

A 10 minute voice note at 64 kbps is about 4.8 MB.

Common uses of the audio compressor

  • Sending voice notes.
  • Shrinking podcast drafts.
  • Saving lecture recordings.
  • Uploading to size limited sites.
  • Reducing phone storage.

Tips and common mistakes

Speech stays clear at 32 to 64 kbps. Music needs 96 kbps or more.

Keep your original file if the recording is important.

Background: what to know before you rely on it

Audio compression removes detail that people are unlikely to hear. Lossy codecs such as MP3, AAC and Opus do this with models of human hearing. Opus is a modern codec that is excellent for speech at low bitrates and is supported in all major browsers. A file at 64 kbps uses about half a megabyte per minute, while uncompressed CD quality audio uses over ten. Each time you compress a lossy file again, some quality is lost, so always start from the best source you have.

Private, free and fast

This tool runs in your browser. Your audio is processed on your device and is not uploaded to a server. It is free to use as often as you like. See more in all pdf and media tools, or browse the full list of tools.

Frequently asked questions

Which format is the output?

Opus in a WebM or Ogg file, or M4A in Safari.

Why is it real time?

The browser re records the audio as it plays.

Is my audio uploaded?

No.

Will it work on MP3 and WAV?

Yes, any audio your browser can play.

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Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. Always keep your original files. Compression is lossy.