Audio Compressor makes MP3, WAV, M4A and other audio files smaller so they fit in an email, a chat app or an upload form. Choose a size or type a target in MB; mono and a lower bitrate do the rest. It works on the sound of videos too.
How to compress audio
- Choose an audio file (or a video).
- Under Size, pick a preset or Target file size and type the limit in MB.
- Pick the format under Save as: MP3, M4A / AAC or OGG / Opus.
- Click Compress. The status line shows the bitrate that was used and whether the file was made mono. Listen to it and download.
Sizes for one hour
| Setting | One hour | Good for |
|---|---|---|
| 96 kbit/s stereo | about 43 MB | Music |
| 64 kbit/s | about 29 MB | Podcasts, lectures |
| 32 kbit/s mono | about 14 MB | Voice notes, meetings |
How the target size works
The tool divides your target size by the length of the audio and keeps a 3% margin for the file’s own overhead. MP3 only allows fixed bitrates (32, 40, 48, 64, 80, 96, 128, 160, 192 kbit/s and so on), so for MP3 the next lower step is used and the file usually comes out a little under the target. Below 48 kbit/s the audio is always made mono, because two channels at such a low rate sound worse than one.
| Target | Length | Result (MP3) |
|---|---|---|
| 8 MB | 5 min | 192 kbit/s stereo |
| 25 MB | 45 min | 64 kbit/s |
| 25 MB | 90 min | 32 kbit/s mono |
The bitrate never goes above 320 kbit/s, and a target that would need less than 24 kbit/s is refused, with a message to choose a larger size.
Tips for small files that still sound good
- Speech: tick Mono. One channel needs half the data, so at the same size a voice sounds clearer.
- Very small sizes: choose OGG / Opus. It stays clear at 32 kbit/s where MP3 sounds watery. Use MP3 when the file must play on every device.
- Start from the original: compress the best copy you have, not a file that was already compressed. Every lossy save loses a little more.
- Check before you send: play the result in the preview, especially quiet parts and music, then download.
Private by design
Your files are processed on your own device and never uploaded. See how it works.