Audio Compressor
Make audio files smaller without leaving the browser.
Up to 50 MB per file. Sign up free to compress files up to 100 MB.
| File name | Size | Compress to |
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Checking files and selected compression settings.
This page stops at 50 MB and one file per run. Pro compresses files up to 1 GB and a full batch in one go, with a priority queue.
What audio compression does
Audio has one lever that images do not: bitrate, the number of kilobits spent on every second of sound. Because it is per second, the size of an audio file is set by its length as much as by its quality. At 128 kbps, the rate most MP3s arrive at, one megabyte holds about sixty-five seconds. Five megabytes holds five and a half minutes. That arithmetic, rather than the size of the file you started with, decides whether a target is comfortable or impossible.
Speech and music behave differently under it. A single voice stays clear down to 48 or 64 kbps in mono, so a half-hour interview fits inside 10 MB without anyone noticing. Music wants 128 kbps and upwards in stereo; pushed to 47 kbps, which is what a three-minute track needs to reach 1 MB, it turns thin and hollow. Folding a mono source to one channel is the one saving that costs nothing at all, because there was never a second channel worth keeping.
WAV is the exception. It stores sound uncompressed, so it carries no bitrate to lower, one megabyte of CD-quality WAV is under six seconds of audio. Making a WAV meaningfully smaller means encoding it to MP3, which this tool does rather than pretending a lossless file can be squeezed.
If you already know the format you are working with, go straight to the MP3 Compressor or the WAV Compressor. If you have been given an exact ceiling to meet, the size-targeted pages below go straight to it.
How to compress audio online
Upload your audio
Drop in MP3 or WAV files, or click to browse. Nothing is installed and nothing is kept: uploads travel over HTTPS and are deleted within the hour.
Choose a target size
Pick the ceiling you have been given. The encoder works out the bitrate that reaches it for the length of your recording, dropping to mono and a narrower band only when the target leaves it no other option.
Download the result
The file comes back under your target, not padded up to it. If the audio reaches an acceptable bitrate below the cap, it is left there.
Stereo goes before the bitrate floor
You give it a ceiling in megabytes and it solves for the bitrate that meets it at your recording's length, rather than asking you to guess which quality preset lands where.
Stereo is kept while the budget allows it. Folding to a single channel halves the data and is the first thing tried when a target cannot be met any other way.
An uncompressed file has no bitrate to reduce, so a WAV is encoded to MP3 to reach your target. That is a real change of format, and the tool says so rather than hiding it.
The common ceilings have pages of their own, 1, 2, 5 and 10 MB, because the target is usually somebody else's number that has to be satisfied exactly.
Compress several recordings against one target and download them together. Batch size follows your plan, up to 100.
Uploads are encrypted in transit and removed within an hour of processing. Nothing is stored permanently and nothing is shared.