How to set the level
Each file is scaled so its loudest moment lands here, which means a different amount per file. −1 dBTP is the safe choice; 0 can distort once the file is re-encoded.
Holds the gain back if the peak would pass −1 dBTP. Turn it off and the full amount is applied, but anything above 0 dB is chopped flat on export and audibly distorts.
Export
WAV is 24-bit and uncompressed, so nothing is lost. MP3 re-encodes, so choose WAV if the file is going back into an editor. Output is two channels; a WAV source keeps its own sample rate, other formats come out at 44.1 kHz.
The levelled audio lands here, with how much each file was moved.
Lift a recording that came out too quiet, or bring a set of files recorded at different levels into line. Peak (dBTP) and loudness (LUFS) are measured before and after, and any setting that would distort is flagged before you run it. Exports WAV and MP3.
Formats
MP3 / WAV / FLAC and more
Questions
Does this degrade the audio?
The gain itself does not. The export format matters more: WAV is 24-bit and uncompressed, MP3 is a re-encode. Choose WAV if the file is going back into an editor. Note also that turning a recording down turns its noise floor down with it — and turning it up brings that noise up too.
What happens if I turn the clip guard off?
The full amount is applied and anything above 0 dB is flattened when the file is written. That is distortion, and it is not reversible from the exported file. Leave it on unless the distortion is what you are after.
How many files at once?
There is no fixed limit, but every decoded file is held in memory. Dozens of full-length tracks will make a modest machine struggle. Measurement also runs one file at a time, so the wait grows with the number and the length of what you add.
What comes out?
Two channels. A WAV source keeps its own sample rate; other formats come out at 44.1 kHz, because a compressed file does not reveal its rate until it has been decoded. A mono source is written as two identical channels, because some players mishandle a single-channel WAV. WAV output is 24-bit.
Are my files uploaded?
No. Decoding, measurement, processing and encoding all happen in the page, and closing the tab discards everything that was loaded.