MP3 compressor – shrink audio files for WhatsApp, email and web
Chat shortcut: /mp3compress
MP3 compressor in one run: upload audio, choose a bitrate, download the MP3. After the run you see the size before and after; the file gets smaller when the new bitrate is below the old one.
No Sign-Up
Free · The uploaded file is deleted after 24 hours; the result stays in “My media”.
Smaller with the bitrate the content needs
A voice recording exceeds the messenger's limit, a podcast rough cut doesn't fit in the email, audio samples on the website load too slowly: often the bitrate is higher than the content needs. Speech gets by with a fraction of the data rate usual for music; whether a difference is audible depends on content, bitrate and playback device.
The tool re-encodes your audio file at the chosen bitrate and outputs an MP3. You choose between 32 and 128 kbit/s and decide whether both channels are merged to mono; at 32 and 48 kbit/s the sample rate is additionally lowered to 22,050 Hz. After the run, the size before and after are shown side by side; if it doesn't fit yet, start again with a smaller level.
How it works
- 1
Upload audio
Drop in or choose an MP3, M4A, WAV, OGG, FLAC or AAC up to 50 MB and 60 minutes.
- 2
Choose bitrate
32 to 64 kbit/s for speech, 96 or 128 for music; for speech, check “Convert to mono”.
- 3
Download
Click “Let's go”, compare the size before and after, save the MP3.
Good to know
- Input: MP3, M4A, WAV, OGG, FLAC, AAC up to 50 MB and 60 minutes. Output: always MP3, one file per run, without embedded cover images.
- Bitrate 32, 48, 64, 96 or 128 kbit/s (default 64); at 32 and 48 kbit/s sample rate 22,050 Hz; mono option for speech. Rule of thumb: 64 kbit/s ≈ 0.5 MB per minute, 128 kbit/s ≈ 1 MB per minute.
- The file only gets smaller if the chosen bitrate is below that of the original; uncompressed WAV and losslessly compressed FLAC shrink the most.
- Processing on our server; the input is deleted after 24 hours (hourly cleanup), the result stays in your media library.
- Free, no sign-up, no watermark. Chat shortcut: /mp3compress.
Frequently asked questions
Which bitrate should I choose?
For speech, audiobooks and podcasts, 48 to 64 kbit/s in mono is usually enough; at 32 and 48 kbit/s the sample rate also drops, so high frequencies are lost. For music, 96 to 128 kbit/s in stereo is a compromise; below that, cymbals and reverb become audibly flatter. MP3 is lossy, so keep the original.
How big will the file be, for example for WhatsApp or email?
The size follows the bitrate: 128 kbit/s gives around 1 MB per minute, 64 kbit/s about 0.5 MB, 32 kbit/s about 0.25 MB. A 30-minute recording is around 14 MB at 64 kbit/s and around 22 MB at 96 kbit/s; check your messenger's or email provider's help for its attachment limit.
Why didn't the file get smaller?
The chosen bitrate wasn't below that of the original. An MP3 at 64 kbit/s doesn't get smaller at 64 kbit/s, it's only re-encoded; choose a lower level. Mono alone doesn't change the file size at the same bitrate.
What does mono do?
Both channels are merged into one, and the whole bitrate is available to that one channel. Speech sounds cleaner at the same bitrate as a result, but the file doesn't get smaller by that alone; with music, the stereo image is lost.
Which formats can I upload?
MP3, M4A, WAV, OGG, FLAC and AAC up to 50 MB and 60 minutes. The result is always an MP3; uncompressed WAV and losslessly compressed FLAC shrink the most.
What happens to my file?
The input is deleted 24 hours after upload (hourly cleanup); the result stays in your media library. Compressing is free, without sign-up and without watermark.