Your browser decodes the file.
The sound is decoded on this device at 44.1 kHz, or at 22.05 kHz if you choose it for speech. At 22.05 kHz an MP3's bitrate stops at 160 kbps.
SOLIPSIUM Super resolution audio engine
Free audio tool
Make an audio file smaller, to a size you choose.
Type the size you need, such as an email limit, and your browser saves an MP3 at the highest bitrate that fits. You see the size before you save it.
Drop a recording here
Your browser makes it smaller on this device. It stays on your device until you ask for a repair.
MP3, WAV, M4A, FLAC, Ogg and more, up to 30 minutes or 200 MB.
Ready to compress
An MP3 holds at most two channels, so this file's channels are folded into stereo, or into one for mono.
Is the recording itself clear?
A smaller file does not clean the sound. Solipsium's free try is built for speech: the check below looks in your browser for background noise, hum, clipping, dropouts and muffled sound, and you can hear the first 20 seconds of a voice recording repaired with no account.
Your first 20 seconds
After signing up, drop the same file into the editor to repair all of it.
What Solipsium hears
Make a free account to repair the whole recording
Then drop the same file into the editor. Scans and short repairs are free.
How it works
The bitrate comes from the size you type.
A constant-bitrate MP3's size is its bitrate times its length. The page divides the size you type by the recording's length and picks the highest MP3 bitrate under it.
Mono, if you choose it.
Mono averages the channels into one. An MP3's bitrate covers all its channels together, so mono makes a file the same size as stereo at the same bitrate and spends all of it on one channel.
The MP3 is written.
The MP3 has a constant bitrate from 32 to 320 kbps. It is made with lamejs, a JavaScript port of LAME, under the GNU LGPL, and comes out at or a little under the size shown.
Questions
Before you compress.
How small can a voice recording go?
Choose mono and 22.05 kHz, then a low bitrate. At 32 kbps, the lowest here, a minute takes about 240 KB.
Will it sound worse?
At lower bitrates, yes. An MP3 saves space by leaving sound out, and under 64 kbps you can hear the treble go and a swishy sound come in. Play the file before you send it.
What size limit does my email or app have?
Each service sets its own. Type the limit your service shows. Sizes here count a megabyte as 1,000,000 bytes, so a file made for 10 MB fits a limit counted either way.
Why not a WAV?
A WAV is not compressed. A minute of 44.1 kHz stereo takes about 10.6 MB as a 16-bit WAV, eleven times a 128 kbps MP3 of the same minute.
A video that is too big?
This page saves the sound only. Video compressor makes a video smaller, to a size you choose.
Is my file uploaded?
Not to compress it. Your browser opens the file and makes the MP3 on this device, and Solipsium's check of the recording runs in your browser too. Audio is sent only if you press Repair the first 20 seconds. For a mono or stereo recording of up to five minutes, only its first 20 seconds leave this browser; Solipsium repairs them on its server and deletes them within an hour. A longer file would have to go whole, so the try is offered for it only up to 25 MB, and Solipsium keeps just its first 20 seconds.
A noisy voice recording?
Drop it on the home page. The check runs in your browser, and you can hear its first 20 seconds repaired with no account.
Check a recording
The check and the 20-second try need no account.