An email attachment limit, a podcast host with strict upload caps, a voice memo that’s somehow 40 MB for two minutes of talking. Audio files get bloated fast, and re-encoding them by hand means digging through software you probably don’t have installed. This compressor drops that step: pick a preset or a target size, and your browser does the rest.
Compress Audio - Reduce Audio File Size Free
Compress MP3, WAV, M4A and more in your browser. One-click presets or a target file size, batch process, download as ZIP. No uploads, 100% private.
Drop audio files here or click to upload
MP3, WAV, OGG, M4A, FLAC • Max 100MB each
The bitrate for each file is calculated from its length to fit the target size.
Your audio stays on your device. Nothing is uploaded or sent anywhere.
How compression works here
Add one or more audio files, and each one gets a live size estimate based on its length before you even click anything. Pick a preset (Smallest, Balanced, or Best Quality) or switch on target size mode and type in a number of megabytes. Hit Compress, and every file is decoded, re-encoded as MP3, and ready to download, either one at a time or all together as a ZIP.
If a file is already small enough that re-encoding wouldn’t help, it’s kept as-is instead of being needlessly re-processed. You’ll see “already small” next to it rather than a percentage saved.
Choosing a preset
Smallest encodes at 64 kbps, mono, downsampled to 22 kHz. It’s built for voice: memos, interviews, lecture recordings, anything where clarity of speech matters more than fidelity. Files shrink dramatically, often to a fraction of their original size.
Balanced encodes at 128 kbps in stereo, a sensible middle ground for music or mixed content where you still want it to sound decent but don’t need archival quality.
Best Quality goes up to 256 kbps in stereo, for when the main goal is trimming a bit of size off a large file without a noticeable drop in how it sounds.
Compressing to a target size
Sometimes a preset isn’t precise enough, you need the file under a specific number because of an email limit or an upload cap. Turn on Compress to a target size, enter how many megabytes you’re aiming for, and the tool works out the exact bitrate needed based on each file’s length to land close to that size.
A three-minute voice memo and a forty-minute podcast episode need very different bitrates to both fit under, say, 5 MB, and the calculation happens automatically per file rather than applying one bitrate to everything.
Batch compressing multiple files
Drop in as many files as you want. Each one shows its own estimated size reduction before compressing and its actual result after. Once two or more files are done, a Download All button appears and packages everything into a single ZIP, so you’re not saving files one by one.
Why the output is always MP3
Compression only makes sense with a lossy format, since that’s what actually discards data to shrink the file. MP3 is the practical choice here: universally supported, playable on literally anything, and at these bitrates the size savings are substantial. If you need the compressed file in a different container, the Audio Converter can convert it afterward.
Nothing leaves your browser
Every file is decoded, resampled, and re-encoded using the Web Audio API and JavaScript running locally on your device. No file is ever uploaded to a server, which matters for anything you’d rather not hand over: personal recordings, private interviews, unreleased music. Since the work runs on your own processor, longer files take a bit more time to process than short clips, which is expected for in-browser encoding.
Need to trim a file down before or after compressing it? The Audio Cutter lets you cut out just the section you need. If you’re combining several clips into one file, the Merge Audio tool joins them together first.
Frequently Asked Questions
How much can this tool shrink an audio file?
It depends on the original bitrate and the preset chosen. Uncompressed formats like WAV often shrink to 5-10% of their original size at the Smallest preset. Already-compressed MP3s see smaller but still meaningful reductions.
Will compressing reduce audio quality?
Yes, since MP3 compression is lossy by nature. The Balanced and Best Quality presets keep the difference minimal for most listening. The Smallest preset trades noticeably more quality for a much smaller file, which is fine for speech but less ideal for music.
What does 'target size' mode actually do?
You enter a size in megabytes, and the tool calculates the bitrate needed for each file's specific length to land close to that target, rather than using one fixed bitrate for every file.
What happens if a file is already small?
If re-encoding wouldn't actually shrink the file, the original is kept instead of producing a larger or unnecessary re-encode. It's marked as already small.
Can I compress multiple files at once?
Yes. Add as many as you need, they compress one after another, and once two or more finish you can download them all together as a ZIP.
Is there a file size limit?
Each file can be up to 100 MB before compression.
Are my audio files uploaded anywhere?
No. Everything happens in your browser using the Web Audio API. Files are never sent to a server.