Compress Audio
Compress Audio reduces a file's size by lowering its bitrate and encoding to MP3 or AAC. It's ideal for shrinking large WAV recordings for email or upload. Pick a bitrate, export in your browser, and see how much smaller the file became.
Add your audio file
The file is read by your browser and stays on your device — there is no upload step.
Your audio
The work runs in this tab. Nothing is sent anywhere, and the download is generated locally.
Output —Load audio
How to use Compress Audio
- 01Upload
Add your audio
Drop a WAV, FLAC, MP3 or AAC file in; its size is displayed.
- 02Customize
Choose settings
Pick MP3 or AAC output and select a target bitrate from 64k to 256k.
- 03Process
Compress
Export to shrink the file and see the size reduction.
Which bitrate is honest for this material?
Speech and music have very different needs, and matching the bitrate to the content saves far more than pushing a slider.
- Speech / podcast96 kbps mono
A voice occupies a narrow frequency range. Mono at 96 kbps is transparent for spoken word and roughly a quarter the size of stereo at 192.
- General listening192 kbps
The sensible default for music that will be played on phones, laptops and in cars. Most listeners cannot reliably pick this apart from the source.
- Keep it close320 kbps
The top of what MP3 offers. Worth it for material you care about, but the saving over 192 is modest and the audible gain is smaller still.
What changes, and what does not
The frequencies the encoder judges you will not miss — mostly the very top end, and detail masked by louder sounds nearby. Cymbals and applause are where it shows first.
Length, speed, pitch and channel count unless you change them. Compression does not shorten or alter the performance.
What you are choosing
- Bitrate
Data per second. The dominant factor in both size and quality. Doubling it roughly doubles the file.
- Channels
Mono halves the data of stereo. For a single speaker it is the single largest saving available and costs nothing you would notice.
When compression is not the answer
- There is a long silent stretch in the recordingRemove Silence
- Only part of the recording is neededTrim Audio
- It is a stereo file of one person talkingMono / Stereo
- The format is the problem, not the sizeConvert Audio
Supported formats
- MP3
- WAV
- M4A
- OGG
- FLAC
- Maximum file size —
- bounded by your device's memory
- Processed by —
- FFmpeg (WebAssembly), on your device
Your file, and what the page does
Your file is never uploaded. Compress Audio reads it into this browser tab and processes it with FFmpeg compiled to WebAssembly on your own device. There is no upload endpoint in the application and no copy on any server — closing the tab discards it.
That is also why processing takes longer here than on a site that uploads: your device is doing the work rather than a rack of servers. The trade is that the file never leaves it.
What the page does send or fetch
- The processing engine, once
- The first time you use any video or audio tool, the browser downloads the FFmpeg WebAssembly build (~30MB) from the jsDelivr CDN and reuses the cached copy afterwards. That is a file coming to you — no part of your own file is in the request.
- Ads on the page
- The site is funded by advertising, so the page loads Google AdSense. That carries the usual web basics — IP address, browser, referring page — as on any ad-supported site.
- An anonymous usage counter
- When Compress Audio finishes we record that the tool ran, whether it succeeded and how long it took. No file data, no identifier, no cookie.
Your file is not on that list. How this works.
Frequently asked questions
128 kbps is a good default for speech and music; lower for smaller files, higher for better quality.
MP3 and AAC are lossy, so very low bitrates lose detail — the bitrate options let you balance size and quality.
Dramatically — an uncompressed WAV converted to a 128k MP3 is often a tenth of the size.
Yes — Compress Audio is completely free. There's no account, sign-up, watermark or limit.
No. It runs in any modern browser — Chrome, Edge, Safari, Firefox, Brave — with nothing to download or install.
Not sure compressing is what you need?
- Too large, and the whole recording mattersCompress Audio
- Only a section is neededTrim Audio
- Long gaps of nothingRemove Silence
- One voice recorded in stereoMono / Stereo
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