Compress Audio
Make a recording small enough for an email, an upload form or a phone that is running out of space. Type the size you need, or choose a bitrate, and get back the same audio in a fraction of the bytes.
Compress Audio
or drop MP3, WAV, M4A … files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
MP3 plays everywhere. Opus and M4A sound better than MP3 at low bitrates such as 48–64 kbps.
Mono halves the data needed and is ideal for voice recordings, lectures and podcasts.
Lowering it to 22.05 or 16 kHz saves space on speech; keep it for music.
How to use this tool
- 1
Upload the audio
Add MP3, WAV, M4A, AAC, FLAC, OGG, Opus, AIFF, WMA, AMR, M4B or CAF files, up to 20 at a time and 95 MB each.
- 2
Set a size or a bitrate
Compress by starts on Bitrate at 128 kbps. Switch to Target size and type a number in KB or MB when a form or mail service sets a limit.
- 3
Compress and download
Press Compress to MP3 (or the format you chose) and download each smaller file, or all of them in one ZIP.
Audio file size is bitrate times length. Lower the bitrate, or let the tool calculate it from the size you type, and the file shrinks in direct proportion.
How an audio file compressor shrinks a recording
Every compressed audio format stores a fixed budget of data per second, the bitrate. An MP3 at 128 kbps spends 128,000 bits, or 16 KB, on each second of sound, which works out to about 1 MB per minute whatever is being played. To make a file smaller, the encoder is given a smaller budget and has to decide which details to drop. Modern codecs drop the ones human hearing is least sensitive to first, such as very high frequencies and sounds masked by louder ones nearby.
That is why the result depends on what you compress. Speech has a narrow frequency range and survives low bitrates well; a symphony or a dense rock mix starts to sound swirly or thin much sooner. Channels set to Mono halves the data needed for a voice recording, and lowering Sample rate to 22.05 or 16 kHz frees more bits for what remains. Both are wasted on music, where you should keep the source settings.
Uncompressed WAV and AIFF files see the biggest drop, often to a tenth of their size. If your goal is a different format rather than a smaller file, the audio converter gives more format choices, and trim audio removes the parts you do not need, which is the one change that saves space without any loss at all.
MP3 file size per minute at each bitrate
| Bitrate | Per minute | Per hour | Fits in a 25 MB email | Good for |
|---|---|---|---|---|
| 32 kbps | 0.24 MB | 14.4 MB | About 104 minutes | Speech only, mono |
| 48 kbps | 0.36 MB | 21.6 MB | About 69 minutes | Lectures and calls, Opus or M4A |
| 64 kbps | 0.48 MB | 28.8 MB | About 52 minutes | Podcasts and voice notes |
| 96 kbps | 0.72 MB | 43.2 MB | About 34 minutes | Audiobooks, background music |
| 128 kbps (default) | 0.96 MB | 57.6 MB | About 26 minutes | Music for most listeners |
| 160 kbps | 1.2 MB | 72 MB | About 20 minutes | Music with more headroom |
| 192 kbps | 1.44 MB | 86.4 MB | About 17 minutes | Music you care about |
5-minute song as WAV
52.9 MB
44.1 kHz, 16-bit stereo, 1,411 kbps
Compressed to MP3
4.8 MB
128 kbps, stereo, calculated size
MP3, M4A, Opus or OGG for compressed audio
MP3
Plays on every device, browser, car stereo and upload form.
- Best choice when you do not know the player
- Sounds thin below about 64 kbps
- Up to 192 kbps here
Opus
The IETF codec from RFC 6716, built for voice and music over the internet.
- Clean speech at 32–48 kbps
- Used by browsers, WhatsApp and Discord for voice
- Not every car stereo or old player supports it
M4A or OGG
M4A holds AAC audio, native on iPhone and Mac; OGG holds Vorbis, common in games and Linux.
- M4A beats MP3 at 64–96 kbps
- OGG suits web and game assets
- Both keep tags
Compress audio online: settings to check
- Compress by: Target size for a fixed limit, Bitrate when you care about sound quality first.
- Target size and Unit: from 1 KB upward; one minute of 128 kbps MP3 is about 1 MB, so plan around that.
- Bitrate: 32, 48, 64, 96, 128, 160 or 192 kbps; 64 kbps is plenty for podcasts.
- Output format: Same as source, MP3, M4A, Opus or OGG.
- Channels: Mono for any single voice; it halves the data needed.
- Sample rate: 22.05 or 16 kHz for speech, Same as source for music.
- Trim silence and Strip tags and cover art: small extra savings, a large cover image alone can add several hundred KB.
Compress audio questions
How do I compress an audio file to a specific size?
Set Compress by to Target size, type the limit in Target size and pick KB or MB. The tool reads the length of the recording and calculates the bitrate that lands at or just under your number. Long recordings with small targets end up at low bitrates, so add Mono for speech to keep it clear.
Is this the same as an audio compressor in music production?
No. In a studio, a compressor is an effect that narrows the gap between loud and quiet parts, the dynamic range. This tool is a file compressor: it reduces the number of bytes by re-encoding at a lower bitrate. The loudness of your audio stays as it was.
Which format compresses audio best?
At low bitrates, Opus sounds clearly better than MP3, and M4A (AAC) sits in between. At 128 kbps and above the differences fade. Choose MP3 when you do not know what will play the file, and Opus or M4A when the app or website lists them.
Why did my MP3 barely get smaller?
It was already at or below the bitrate you chose. A 128 kbps MP3 compressed at 128 kbps stays the same size. Pick a lower bitrate, switch Channels to Mono, or turn on Strip tags and cover art if the file carries a large embedded image.
Can I compress a WAV without converting it to MP3?
Choose Same as source under Output format and the file keeps its format; for WAV the size then shrinks only through Channels and Sample rate, because WAV is uncompressed. For a large saving, convert to MP3, M4A or Opus, or use WAV to MP3.
Can I shrink an M4B audiobook?
Yes, M4B files are accepted. Audiobooks are spoken word, so 64 kbps in mono with M4A as Output format keeps them clear at roughly half a megabyte per minute. Check the result in your player, since some apps show chapters only for files with the .m4b extension.
How small can a voice recording get and still be understandable?
Speech stays clear at surprisingly low settings. 32 kbps mono, at 16 kHz sample rate, is enough to follow a lecture or an interview, and Opus at that bitrate sounds noticeably cleaner than MP3. Music needs far more, so keep it at 96 kbps or higher.
Does compressing audio remove silence too?
Only if you turn on Trim silence, which cuts silent stretches at the start and end of the recording. Pauses in the middle are left alone, so the timing of speech and music does not change.
| Audio Converter | Trim Audio | Audio to Text |
| Compress Video | Video to Audio | Audio to Video |