LUFS Meter

What is LUFS?

LUFS stands for Loudness Units relative to Full Scale. It is the standard way to measure how loud audio actually sounds to a listener, defined by the EBU R128 / ITU-R BS.1770 specifications. One loudness unit (LU) corresponds to one decibel, but unlike a raw dB reading, LUFS is weighted to match human hearing and is measured across the whole program — which is why every podcast platform, streaming service and broadcaster states its delivery spec in LUFS.

LUFS vs dB

A dB (dBFS) meter shows the instantaneous electrical level of the signal — how close a single sample gets to digital full scale. A loudness meter in LUFS answers a different question: how loud does the program sound overall? Two files can peak at exactly the same dBFS yet differ by 10 LU in perceived loudness, because loudness depends on frequency content and density over time, not just peaks. That is why an online decibel meter can't tell you whether your podcast meets spec, but a LUFS meter can.

Integrated vs short-term loudness

Integrated loudness is the single LUFS number for the entire file — the value platforms normalize against and the headline figure in this meter's report. Short-term loudness (3-second window) and momentary loudness (400 ms) describe how loudness moves moment to moment; the spread of that movement is the loudness range (LRA), also included in your report. A high LRA means large swings between quiet and loud passages — fine for cinema, risky for podcasts heard in cars and on earbuds.

Why platforms normalize loudness

Spotify, YouTube and Apple Podcasts automatically turn every upload toward a house loudness level so listeners don't reach for the volume knob between tracks or episodes. If your file is louder than the target, it simply gets turned down — any loudness you "won" in mastering is thrown away, and you keep the distortion. If it is much quieter, some platforms turn it up and may limit the peaks. Delivering at the target keeps you in control of how your audio sounds after normalization.

Platform loudness targets at a glance

The ruler above plots every major loudness delivery target on one scale, from loudness-war-era CD masters at the top to dialogue-gated streaming mixes at the bottom. The full table:

Two kinds of numbers share this table, and the difference matters. A published spec is a document the platform or standards body has put its name to — EBU R128, ATSC A/85, ARIB TR-B32, Free TV OP-59, the Netflix and Amazon delivery specifications, Apple's podcast and immersive-audio authoring guides, Spotify's normalization page, and the AES TD1008 guidance for streaming. A measured practice is the community consensus about what a platform actually does to uploads: YouTube, Tidal, Amazon Music, Deezer and Apple Music publish no loudness document, so their figures come from controlled measurements by metering vendors and mastering engineers and could shift without notice. Deliver to a published spec with confidence; treat a measured practice as a well-informed aim point, and leave a little margin.

A few names are deliberately absent. Disney+ and Apple TV+ have no public spec — claims about Disney+ circulate, but they conflict and trace back to private documents — and the primary document for China's GY/T 282-2014 is unreachable, so plotting any of them would be guessing. SoundCloud and Bandcamp do no loudness normalization at all: your file plays exactly as uploaded, so there is no target to hit. Finally, don't be confused by the units: LUFS and LKFS are numerically identical. Broadcasters write LKFS, music platforms write LUFS, and −23 of one is exactly −23 of the other.

The gain-offset formula

The math of hitting a target is a single subtraction:

offset (LU) = target − measured

Say the meter above reports −21.4 LUFS integrated and you are delivering to Spotify at −14 LUFS. The offset is −14 − (−21.4) = +7.4 LU: apply 7.4 dB of gain and the loudness lands exactly on target. A negative offset means you are too loud and must turn down by that many decibels instead. Because one loudness unit is one decibel, the gain figure and the loudness figure are always the same number — that is the whole convenience of working in LUFS, and it is what the gain-offset calculator above computes for any platform on the ruler.

The catch is the true peak. Plain gain shifts the entire waveform up or down, so your true peak moves by exactly the offset as well. If that −21.4 LUFS master already peaks at −0.4 dBTP, the +7.4 LU offset pushes the peak to −0.4 + 7.4 = +7.0 dBTP — far beyond 0 dBFS, clipping hard on any playback system, and miles over Spotify's −1 dBTP ceiling. When the calculator flags clip risk, pure gain is the wrong tool for the move: use a limiter or a loudness normalizer that can raise loudness while holding the peak ceiling, then re-measure the result to confirm both numbers landed. Turning down, by contrast, is always safe — a negative offset only ever lowers the true peak, which is why platforms simply turn loud uploads down rather than up.

1. Upload an MP3, WAV, FLAC, AAC, M4A or OGG file — the meter reads the whole program, not a sample of it.

2. Read the integrated LUFS, true peak in dBTP and loudness range, then find your platform on the loudness ruler.

3. Apply the gain offset the meter gives you, or hand the file to the Volume Normalizer to land on the target in one click.