WAV to MP3
Choose a WAV or AIFF master and get a 192 kbps MP3 of it, converted inside this browser tab at about a seventh of the size of a 16-bit stereo WAV, and at the master’s own sample rate wherever the encoder can write it. The master never leaves your machine, and the before and after play side by side so you can hear what the compression cost.
Ready.
Why compress a master
A WAV is uncompressed: the right file to edit and archive, and a heavy one to send, upload or listen through on a phone. The MP3 is the copy for everything else. Keep the WAV either way, because MP3 is lossy and a later edit should start from the master.
| File | Size per minute | One hour |
|---|---|---|
| 16-bit stereo WAV, 44.1 kHz | about 10.6 MB | about 635 MB |
| 16-bit mono WAV, 44.1 kHz | about 5.3 MB | about 318 MB |
| 192 kbps MP3 | about 1.4 MB | about 86 MB |
Worked out from the formats themselves: a WAV is its sample rate times its bytes per sample times its channels, and a 192 kbps MP3 is 192,000 bits a second whatever is in it.
Quality settings and limits
There is no bitrate menu to get wrong. Every master is converted with the same settings, and the result says which applied.
Making an MP3 for ACX?
This converter keeps the level exactly as it is. ACX’s requirements ask for RMS between −23 and −18 dB, peaks at −3 dB or lower, a noise floor of −60 dB RMS or lower and a 192 kbps or higher constant-bitrate MP3 at 44.1 kHz, so a 48 kHz master converted here still fails on its sample rate. The chapter checker measures all of them, fixes what fails and writes the MP3 in the same step; the batch checker does a whole book.
Where the file goes
The master is read and encoded inside this browser tab. The tools on this site never upload your audio, so there is nothing to delete later. There is no queue behind other people’s jobs and no paid tier for longer files; the limit is your own device.
Straight answers
Choose the WAV or AIFF. It is read in chunks inside this tab, encoded as a 192 kbps MP3 and handed back as a download, with the first twenty seconds of both to compare by ear. The master is never sent anywhere.
192 kbps, constant bitrate. The MP3 keeps the master's own sample rate when it is 32, 44.1 or 48 kHz and is resampled to 44.1 kHz otherwise, with the page saying so. Mono stays mono and stereo stays stereo. 16, 24 and 32-bit PCM and 32-bit float WAVs are all read.
A 192 kbps MP3 is about 1.4 MB per minute. A 16-bit stereo WAV at 44.1 kHz is about 10.6 MB per minute, so the MP3 is roughly a seventh of its size; against a 16-bit mono WAV, about 5.3 MB per minute, it is roughly a quarter.
Only if the levels already pass. This converter keeps the level and the sample rate exactly as they are, and ACX also measures RMS, peaks, the noise floor and asks for 44.1 kHz. The chapter checker on the home page measures all of them, fixes what fails and writes the MP3 in the same step.
Not a practical one for MP3 output: the master is read and encoded in chunks rather than held in memory whole. It converts one file at a time.