How to use the Audio Compressor
- Drop in the recordings or songs, in any common audio format.
- Choose a bitrate from 160 down to 32 kbps; 96 kbps suits music on a phone, 48–64 kbps suits speech.
- Switch Channels to Mono when it is just voices, then press Compress.
What format you get back
Lossy files, MP3, M4A, AAC, OGG and Opus, stay in their own format and are re-encoded at the chosen bitrate. Uncompressed WAV and AIFF, lossless FLAC and WMA come back as MP3, since a bitrate only means something for a lossy codec. More settings can also make every output an MP3.
If the re-encoded file is not smaller than the one you added, for example because it was already at a low bitrate, you get the original back unchanged.
Sizes for common uses
At 64 kbps one minute of audio takes around 480 KB, at 32 kbps around 240 KB. A single voice in mono remains easy to follow at 32 to 48 kbps, whereas stereo music loses its sparkle under 96 kbps.
For a lone speaker, channel count matters more than bitrate. A mono podcast at 48 kbps beats the same show in stereo at 96 kbps, because no bits go on a duplicate channel.
Planning for a size limit
Work back from the length: multiply kbps by minutes and by 0.0075 to get an approximate size in MB. A 20-minute interview at 48 kbps comes to about 7.2 MB.
A typical song is done in roughly a second, and the queue shows each file’s original and new size side by side.
Questions
Can I compress a WAV and keep it as WAV?
No. WAV has no bitrate setting to lower, so it becomes an MP3, which is where the saving comes from.
Are the recordings uploaded?
No. Everything is re-encoded in your browser.
Can a compressed file come out bigger?
No. When re-encoding does not save space, the original file is returned instead.