Compress Audio

How it works

1. Choose one or more audio files.
2. Pick a quality preset, or set the format and bitrate yourself.
3. Click Compress and compare the before and after sizes.
4. Download the smaller files, or a ZIP of all of them.

Four ways to set the size

Quality picks a sensible bitrate for the format: Low, Medium or High. Bitrate lets you choose the number yourself. Target size works backwards from the size you need: you give a number of megabytes and the tool works out the bitrate. Maximum size does the same, but a file that is already under the limit is returned exactly as it is, which is what you want for a batch where only some files are too big.

Compression here always re-encodes the audio, so the size really changes. Lossy formats lose a little detail each time they are encoded, which is why the quality presets never raise a file above the bitrate it already has. Keep your originals.

What changes the size

• Bitrate is the biggest lever. 128 kbps MP3 is about 1 MB per minute; 64 kbps is half of that and fine for speech.
• Mono halves the data for speech and podcasts, with little audible difference when the recording came from one microphone. Stereo music loses its width.
• A lower sample rate saves a little more and cuts high frequencies, which matters little for speech.
• Tags and cover art can add a megabyte or more to every file. Under More options you can remove them.
• A more efficient format gets the same sound into fewer bytes: Opus and AAC beat MP3 at low bitrates.

Batch results

Add as many files as you like. Each is compressed with the same settings, with its own progress, and one failing file does not stop the rest. The list shows the size and bitrate before and after, the percentage saved, and what the tool changed along the way. Download files one by one or all together as a ZIP.

Questions