Loudness Meter

What it's for

Check that a recording is the loudness the place it’s going expects. Streaming services, podcast apps and broadcasters turn every file up or down to the same loudness, measured in LUFS (loudness units relative to full scale) by the ITU-R BS.1770 standard; a file mixed far off their target gets turned down and sounds flat, or turned up and loses its peaks.

For example, when you’ve edited a podcast episode, open the export here to see whether it’s near −16 LUFS with peaks under −1 dBTP, and save a corrected copy if not.

How to use it

Choose a sound file (WAV, MP3, M4A, Ogg or FLAC, as far as this browser plays them), or drop it on the page. It’s measured at once:

• Integrated loudness: the whole file, with silence and very quiet parts left out as the standard says.
• Loudness range: how much the loudness varies (EBU Tech 3342), in loudness units (LU).
• Loudest 3 seconds and Loudest 0.4 seconds: the short-term and momentary maximums.
• True peak: the highest point including between samples, found by oversampling four times.

The second table compares it with the usual targets. To fix it, choose a Target (remembered in this browser) and Save at this loudness: you get a WAV, or an AAC .m4a or MP3 if you choose one beside the button, turned up or down by the difference. If turning it up would push the true peak above −1 dBTP, it’s turned up only as far as that allows, and the message says so.

Example

In the Tone Generator, save a 1000 Hz sine wave for 5 seconds at volume 10%, and open it here.

It reads −23.0 LUFS, sample peak −20.0 dBFS, and is on target for EBU R 128 but 7.0 LU too quiet for podcasts. With the target at −16, Save turns it up 7.0 dB.

Good to know

It changes the volume only: it doesn’t compress or limit, so a sound with sharp peaks may not reach a loud target without going over −1 dBTP. Use an audio editor’s limiter for that, then measure again.

A mono file is measured as one channel, as the standard says, which reads 3 LU lower than the same sound as stereo; that’s why some podcast guidance gives −19 LUFS for mono. Sound is measured at 48 kHz, so the saved WAV is 48 kHz.