AudioAdjustable qualityRuns in your browser

Compress Audio

Re-encode audio at a lower bitrate to save space. Some detail is discarded to fit the target format; how much depends on the format and your settings.

Not uploaded to any serverConverted on this deviceGone when you close the tabHow this works

Drop your files here

MP3, WAV, FLAC, AAC and 6 more formats · up to 300 MB each

or paste files from your clipboard

Ready when you are

Re-encode audio at a lower bitrate to save space. Everything happens in this tab; nothing is sent anywhere.

⌘K to search converters

How to use it

1
Add your files
Compress Audio works with MP3, WAV, FLAC, AAC, M4A, OGG, Opus, AIFF, WMA and AIFF. Drop them in, browse for them, or paste from your clipboard.
2
Choose your options
Tune bitrate, sample rate and channels — or leave the defaults, which are sensible.
3
Run it and download
Press the button and save the result. Everything happens on your device, and nothing is uploaded.

Privacy, in plain words

Is it safe? Your audio file is not uploaded anywhere

What “uploaded” normally means. On most online converters, pressing the button copies your file across the internet onto a computer owned by that website. That copy is what the word “upload” means, and it is the part nobody explains.

What happens instead. This site does not do it. There is no server here that receives files, so your audio file is read, converted and handed back by the browser you are using right now. It never travels — so there is no copy to store, read, leak or hand over.

Check it yourself in ten seconds

Turn off your Wi-Fi after this page has loaded, then convert a file anyway. It still works, because everything needed is already on your device.

The longer explanation of how this works, and the full detail of what is and is not stored on the privacy page.

Why this matters more than it sounds

An audio file is a conversation. Transcribed by machine — which is cheap now — it becomes searchable text about whoever was speaking. It matters more than it sounds, because of what audio files usually are:

Meeting audio

internal discussion, named people, unannounced decisions

Unreleased music

work whose commercial value depends on control of the master

Call recordings

both sides of a conversation, often legally sensitive

Interviews

a source's voice is identifying even when the name is not said

A file that is never sent cannot be kept, leaked, subpoenaed or used to train anything. That is a property of how this works, not a promise about how carefully it is run.

How Compress Audio works

Re-encode audio at a lower bitrate to save space. Everything happens inside this page: the file is read from your device into memory, processed there, and handed back as a download. It is never sent anywhere, and closing the tab discards it.

What it accepts: MP3, WAV, FLAC, AAC, M4A, OGG, Opus, AIFF and 2 more. Files are identified by their contents rather than their name, so a mislabelled file is still handled correctly.
What you get back: A MP3 file, downloaded straight to your device.
What happens to the data: The result is re-encoded, so some detail is discarded permanently. Starting from the original rather than from an already-processed file keeps that loss to one pass.
Size limit: Up to 300 MB per file. Because the work happens on your own machine, available memory is the real constraint — a laptop handles far more than a phone.

The settings, and what each one changes

Compress Audio exposes 4 settings. The defaults are chosen to suit the common case, so changing nothing is a reasonable way to start.

Bitrate: Choose between 320 kbps, 256 kbps, 192 kbps, 128 kbps and others.
Sample rate: Choose between Keep original, 48 kHz, 44.1 kHz, 22.05 kHz and others.
Channels: Choose between Keep original, Stereo, Mono.
Normalise loudness: Applies EBU R128 loudness normalisation to -16 LUFS.

Measured, not estimated

What this tool actually does to a file

Compressing a two-second WAV at the default 192 kbps.

The result came out 3.6× smaller than the file that went in.

Each row is one document, chosen because this tool behaves differently depending on what is inside the file.
Sample	In	Out	Change
An easy clipThe compressible end of the range — a clean tone, or a moving test pattern — where a codec does its best work.	172 KB	48.4 KB	−72%
A hard clipThe other end — pink noise, or dense video grain. Close to incompressible by design, and the worst case for every codec.	172 KB	48.4 KB	−72%

Produced by this site's own converter. The same code that runs in your browser, at the same default settings, so these are the bytes you would download.

Samples are generated from a fixed seed rather than taken from real photographs or documents, so the corpus is reproducible and carries no licensing question — and so the numbers predict the shape of your result rather than its exact size. Measured 2026-10-01. The method, and the command that regenerates every figure on this page, are on the how it works page.

About these formats

Accepts

MPEG-1 Audio Layer III

The universal lossy audio format.

Extensions: .mp3
MIME type: audio/mpeg
Best for: Music players · Podcasts · Maximum compatibility
Compatibility: Plays absolutely everywhere.

Accepts

Waveform Audio

Uncompressed PCM audio. Perfect quality, big files.

Extensions: .wav, .wave
MIME type: audio/wav
Best for: Editing and mastering · Sound design · Archival
Compatibility: Universal.

Good to know

Compress Audio — questions

How does Compress Audio work?

Re-encode audio at a lower bitrate to save space. Add your files above, adjust anything you want to change, and press the button. The result downloads straight to your device.

Is Compress Audio safe — are my files uploaded to a server?

No, nothing is uploaded. On most online tools, pressing the button copies your file across the internet onto a computer owned by that website, where it is processed and then sent back. That copy is what "upload" means. This tool does not do it: your file is read and processed by the browser you are using right now, stays on this device the whole time, and is discarded when you close the tab. Turn off your Wi-Fi after the page loads and it still works, which is the quickest way to confirm it.

Can I use this on confidential or personal documents?

Yes — that is the case it was built for. Because the file never leaves your device, a confidential document is no more exposed than it is sitting in your own folder: there is no transfer, no copy on anybody else's hardware, no retention period and no staff with access. Nothing about the file is logged either — not its name, not its size, not its contents.