How to use this LUFS meter
Drop a bounced file onto the meter above, or click to choose one. It reports integrated loudness in LUFS, true peak in dBTP and loudness range in LU, the three numbers delivery specs are written in, and compares them with the streaming and broadcast targets in the menu.
The file never leaves your computer. Decoding and measurement run in your browser, so an unreleased cue is as private here as it is in your session.
What the numbers mean
- Integrated loudness (LUFS) is the loudness of the whole file, with silence and very quiet passages gated out so a long fade does not drag the figure down. It is the number every spec targets.
- True peak (dBTP) is the highest point of the waveform between the samples, found by oversampling. It can be higher than any sample, and it is what clips after encoding.
- Loudness range (LU) is the spread between the quieter and louder stretches of the file, measured on 3-second windows. It tells a dubbing mixer how much the material moves.
- Max short-term and max momentary are the loudest 3 seconds and the loudest 400 ms. They explain a loud moment, not the file as a whole.
- Sample peak (dBFS) is the largest sample value. A file can peak at -1 dBFS here and still read above -1 dBTP as a true peak.
Which target applies to you
Streaming services play everything at roughly one level, so a louder master is simply turned down. Spotify documents its level as -14 LUFS and lifts quieter tracks only as far as their peaks allow, leaving 1 dB of headroom. Apple Music, YouTube and TIDAL do not publish a figure the same way, so the meter shows the levels they are commonly measured or reported at and labels them as such.
Music for picture is a different job. A cue is one element of a mix someone else finishes, so the target is headroom rather than volume. With no spec, deliver about -23 LUFS integrated with true peak under -2 dBTP, which is the default this meter compares against first.
The reasoning, and why a cue limited to a streaming level comes back from the dub flat, is in how loud a cue should be. The same guide gives 8 to 15 LU as the range of an orchestral cue that genuinely moves, and the meter reads your loudness range against it.
How the meter works
Loudness is measured to ITU-R BS.1770-4. The audio is K-weighted, momentary loudness is taken over 400 ms blocks every 100 ms, and integrated loudness uses the standard's two gates, an absolute gate at -70 LUFS and a relative gate 10 LU below the ungated level. Loudness range follows EBU Tech 3342, which gates 3-second short-term values at -70 LUFS and 20 LU below their level, then takes the 95th minus the 10th percentile.
True peak is found by interpolating four points between every pair of samples below 96 kHz, two up to 192 kHz, and none above. Surround channels are weighted by 1.41 and the LFE is left out, assuming the WAVE channel order L, R, C, LFE, Ls, Rs.
The meter was checked against signals synthesised to the specifications in EBU Tech 3341, cases 1 to 5, and EBU Tech 3342, cases 1 to 4. Every case reads within the tolerance those documents set, and the checks are part of the site's automated tests.
Mono files
BS.1770 measures a mono file as one channel. Played from two speakers, the same file is 3 LU louder, which is how a stereo meter with a mono file on both sides reads it. Tick "Treat mono as dual-mono" to see that figure.
What it cannot check
Some specs measure dialogue only. Netflix, for example, sets -27 LKFS measured on dialogue, which needs the finished mix and a dialogue-gated meter, so a music cue alone cannot pass or fail it. The meter also cannot predict exactly what a platform's encoder does to a file, beyond warning when the true peak leaves too little room.
A file meter answers the question once the bounce exists. For loudness while you mix, the limiter roundup covers the safety limiters that catch a stray true peak .