LUFS meter online
LUFS measures how loud a song sounds over its whole length, using a weighting that follows human hearing. Drop an audio file below to read its integrated loudness and peak level in your browser, then compare it with Spotify's default level of -14 LUFS.
The file is decoded and measured in your browser. It is not uploaded, and nothing is stored by WBBT.
How the meter measures loudness
The measurement follows ITU-R BS.1770, the method behind EBU R128 and behind the loudness settings of streaming services. The audio goes through a K-weighting filter, which lifts the highs a little and cuts the deepest bass the way a listener perceives them. Then the signal is cut into 400 millisecond blocks that overlap by 75%, and the power of each block is measured.
Two gates keep silence and quiet passages from dragging the number down. Blocks below -70 LUFS are dropped, and then blocks more than 10 LU below the average of the rest are dropped too. The integrated loudness is the average of the blocks that remain. The meter was checked against the standard test signal, a stereo 1 kHz sine wave at -23 dBFS, which reads -23 LUFS.
Reading the numbers
Integrated loudness is the number for the whole song, in LUFS. Momentary maximum is the loudest 400 millisecond block. Loudness range, in LU, shows how much the level moves between quiet and loud sections: a small value means the song stays at a similar level throughout.
The peak shown is the sample peak, the highest sample value in the decoded file. It is not a true peak: a true peak is measured on an oversampled signal and can be a little higher than the highest sample. If you need to prove a true-peak limit, check it in your mastering software.
How Spotify normalises, and what it means for your master
Spotify adjusts playback so that tracks play at a similar level. Its documentation gives -14 dB LUFS as the default (Normal) level, -11 for the Loud setting and -19 for Quiet. A song louder than the target is turned down; the table in the tool shows the change in decibels for your file. Spotify also recommends keeping true peak below -1 dB TP for lossy formats, and below -2 dB when the master is louder than -14 dB integrated LUFS.
This tool does not list the settings of other services, because they change and not every service publishes them. Check each service's own documentation. Making a master louder does not make it play louder where normalisation is on, so choose the level that suits the music, and keep your dynamics.
Questions
What does LUFS stand for?
LUFS means Loudness Units relative to Full Scale. One LU is one decibel of change in perceived loudness, and the scale is anchored to the digital maximum.
What LUFS should my song be?
There is no single correct number. Spotify's default playback level is -14 LUFS and it turns louder tracks down to meet it. Broadcast follows EBU R128, which uses -23 LUFS. Pick the level that fits the music, then use this tool to see what each target would do to it.
Is the peak a true peak?
No. This tool reports the sample peak. A true peak is measured after oversampling and can be slightly higher, so check it in mastering software if a limit depends on it.
Is my song uploaded?
No. Your browser decodes the file on your device and the maths runs there. Nothing is sent to WBBT or anyone else.
Why does my number differ from my plugin?
Small differences of a few tenths of a LU can come from the decoder, from sample rate conversion in the browser, or from how a plugin handles the start and end of the file. Compare against the same file at the same moment.
More free tools
Releasing your own music?
See what WBBT offers independent artists and labels, or send us your music.