Compress Audio Files
Reduce audio file sizes by re-encoding at lower quality. Choose your output format and quality level. Free, private, and entirely browser-based.
Drop files here or browse
Supports MP3, WAV, OGG, AAC, M4A, FLAC - up to 500 MB
Choosing the right format and quality
MP3 for universal compatibility
MP3 offers the best compatibility across devices and players. Great for sharing music, podcasts, and voice recordings.
OGG for open-source projects
OGG Vorbis provides excellent compression with no licensing fees. Ideal for web applications and game audio.
AAC for Apple & streaming
AAC delivers better quality than MP3 at the same bitrate. Best for Apple devices, streaming services, and mobile apps.
Quality presets
High preserves near-original quality, Medium balances size and quality for everyday use, Low minimizes file size for voice or background audio.
How to compress audio files online
Need to shrink an audio file for email, messaging, or web hosting? Our free audio compressor re-encodes your audio at a lower bitrate, dramatically reducing file size while preserving listening quality. The bitrate — how many bits are spent per second of audio — is the single number that controls this tradeoff: a typical CD-quality WAV runs around 1,411kbps uncompressed, while a perceptually-transparent MP3 for most music sits around 128-192kbps — roughly a 90% size reduction for a difference most listeners won't notice on normal playback equipment.
Upload any audio file (MP3, WAV, OGG, AAC, or FLAC up to 500 MB), choose your output format and quality preset, and click compress. MP3 offers universal compatibility, OGG Vorbis is ideal for open-source and web projects, and AAC delivers superior quality per bit for Apple devices and streaming — all three are lossy formats that use psychoacoustic modeling to discard frequency information the human ear is least likely to notice, rather than just truncating the waveform.
Everything runs locally in your browser using FFmpeg WebAssembly. Your audio files are never uploaded to any server. The first use requires a one-time download of the audio engine (~30 MB), after which subsequent operations start immediately.
- 1Upload your audio file. Drag and drop or click to select an MP3, WAV, OGG, AAC, or FLAC audio file.
- 2Choose format and quality. Select your output format (MP3, OGG, or AAC) and quality level (High, Medium, or Low).
- 3Compress and download. Click Compress. The audio is processed in your browser and ready to download in seconds.
Which format and quality for which audio
| Situation | Setting | Why |
|---|---|---|
| A podcast episode or voice memo, mostly spoken word | MP3 or AAC, Low-Medium quality (roughly 64-96kbps) | Speech has far less spectral complexity than music — low bitrates that would sound thin on a mix are usually indistinguishable from source on voice. |
| A WAV recording from a mic or DAW export, going to email | MP3, Medium quality | Uncompressed WAV is typically 5-10x the size of an MP3 at reasonable quality for the same duration; this is nearly always the single biggest win available. |
| A music track for archival or further editing | Don't compress — keep WAV/FLAC, or use High quality if a lossy copy is required | Lossy compression is not reversible; re-encoding an already-compressed lossy file (MP3 to MP3) compounds artifacts each pass, so archives should stay lossless. |
| Background music or a sound effect for a web app | OGG Vorbis, Medium-Low quality | OGG has no licensing overhead and Vorbis typically beats MP3 at equivalent bitrate for non-speech audio, which matters when you're shipping the file to every visitor. |
| An audio file for an iOS app or Apple ecosystem delivery | AAC, Medium-High quality | AAC is Apple's native format and generally delivers better quality per bit than MP3 at the same target, with no compatibility tax on Apple devices. |
Known limits
Compressing an already-lossy file (MP3 to MP3, AAC to AAC) compounds artifacts from both encode passes — the result is never better than starting from the original lossless source, so re-compressing a downloaded MP3 further has a lower quality ceiling than compressing a WAV once at the target bitrate.
Very long audio files (podcasts over an hour, full albums) take proportionally longer to re-encode and use more memory, since the whole file is processed in your browser tab rather than streamed through a server pipeline.
Frequently asked questions
What audio formats can I compress?
You can compress MP3, WAV, OGG, AAC (.aac, .m4a), and FLAC files. Output is available as MP3, OGG, or AAC. These lossy formats achieve the best compression ratios.
Why can't I output WAV or FLAC?
WAV and FLAC are lossless formats that preserve full audio quality. Compressing to WAV or FLAC would often produce files larger than the original. For lossless conversion, use our Convert Audio tool instead.
How much smaller will my file be?
Results depend on the input format and quality setting. Converting a WAV to MP3 at Medium quality typically achieves 80-90% size reduction. Compressing an existing MP3 at Low quality usually reduces size by 30-50%.
Does compression affect audio quality?
Yes, audio compression is lossy. High quality preserves most detail and is indistinguishable from the original for most listeners. Medium is suitable for everyday listening. Low is best for voice content or when file size is the priority.
Does my audio file get sent anywhere while this runs?
No. The re-encode runs through ffmpeg.wasm — the same WebAssembly build of FFmpeg used for this site's video tools — inside a Web Worker, entirely on your device. Nothing about the audio compression pipeline involves a server call; the ~30MB one-time engine download is the codec itself, not a place your file goes.
Learn more
From the blog
How to compress audio for email
Getting a podcast or voice memo under an email attachment limit.