Anonymous
Exactly what I needed
Was trying to upload lecture recordings to Moodle but files too big. This fixed it in 2 minutes. No watermarks, no sign up. Thank you!
Set the file size you need to hit — ToolsCrow works out the bitrate and re-encodes your file as MP3 to match it, right in your browser.
The Audio Compressor makes audio files smaller by re-encoding them as MP3 at a lower bitrate. It reads almost any audio file, applies the compression you choose and shows the exact new size and the percentage saved — and because the result is decoded again for preview, you hear the real quality before you commit.
Presets cover the common cases: a 64 kbps mono voice memo, a balanced 96 kbps file, 160 kbps for music and a 32 kbps mono “smallest possible”. Dropping to mono and a lower sample rate is often the biggest win for speech.
The file size of constant-bitrate audio is bitrate ÷ 8 × duration, so halving the bitrate halves the size. MP3 is encoded with a LAME-derived encoder; at low bitrates the tool also lowers the sample rate (22.05 or 16 kHz) because MPEG-2 rates give better quality per bit at 32–64 kbps. A 128 kbps stereo MP3 uses about 0.96 MB per minute; 64 kbps mono uses about 0.48 MB per minute.
Shrink a recording below attachment limits.
Cut archive size by 50–90%.
Compact long meetings and lectures.
Fit more audio on a device.
| Output | MP3, 32–256 kbps CBR |
|---|---|
| Options | Mono, sample rate 8–48 kHz |
| Preview | Real encoded output |
| Savings shown | vs the source file |
128→64 kbps halves the size; 192→96 also halves it; mono halves it again for equal quality per channel.
No — lossy compression discards detail; keep your original.
MP3 at a controlled bitrate is the most universally compatible way to hit a specific file size — every device and platform can play it back.
It gets very close — the calculation is based on a constant bitrate, so the result typically lands within a few percent of your target.
The tool won't go below 32kbps, since quality below that is rarely usable. For very small targets, shortening the clip first (with the Audio Cutter or Trimmer) gets better quality than an extremely low bitrate.
This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.
Was trying to upload lecture recordings to Moodle but files too big. This fixed it in 2 minutes. No watermarks, no sign up. Thank you!
I send voice notes to family in India and need smaller files. This tool makes it easy. Quality tetap bagus walaupun size kecil. Very user friendly!
I produce 3 podcasts weekly and file sizes were killing my storage. This compressor reduces MP3s by 60% without noticeable quality loss. Batch processing would be nice but still 5 stars!