Short answer: LUFS stands for Loudness Units relative to Full Scale. It measures perceived loudness, averaged over time and weighted to human hearing. Values are negative; closer to zero is louder. Spotify and YouTube play music at about −14 LUFS.
What does LUFS stand for?
Loudness Units relative to Full Scale. “Full scale” is the highest level digital audio can hold (0 dBFS), so LUFS readings are below zero: a quiet acoustic track might measure −18 LUFS, a loud rap master −8 LUFS.
The measurement is defined in the ITU-R BS.1770 recommendation. The European Broadcasting Union built its loudness standard EBU R128 on it, with a target of −23 LUFS for TV and radio. Streaming services use the same measurement with louder targets.
What is LUFS in audio?
A peak meter answers “how high does the waveform go?”. A LUFS meter answers “how loud does this sound?”. To get there it does three things:
- K-weighting. The signal passes through a filter that cuts deep bass and lifts frequencies above roughly 2 kHz by about 4 dB, because the ear is less sensitive to very low frequencies and more sensitive in the presence range.
- Averaging. The energy of the filtered signal is averaged over blocks of 400 milliseconds, summed across channels.
- Gating. Blocks quieter than −70 LUFS, and then blocks more than 10 LU below the average, are left out. Silence and fade-outs do not drag the number down.
LUFS vs dB
One loudness unit (LU) is the same size as one decibel. Turn a track up by 3 dB and its LUFS reading rises by 3. So the scale is familiar; what differs is what is being measured.
| dBFS (peak) | LUFS | |
|---|---|---|
| Measures | Level of individual samples | Perceived loudness over time |
| Frequency weighting | None | K-weighting, close to human hearing |
| Typical use | Avoiding clipping | Matching loudness between songs, platform targets |
| Example | Two tracks both peak at −1 dBFS | …and measure −18 and −8 LUFS |
That is why a peak meter cannot tell you whether a master is loud. Heavy limiting keeps peaks at the same ceiling while pushing the average, and only a LUFS meter shows the difference.
LUFS to dB
Differences convert one to one: going from −14 to −9 LUFS means 5 dB more loudness. An absolute LUFS value is not a dBFS value, though, and cannot be converted to a peak level. You need to measure both.
LKFS vs LUFS
Same measurement, two names. LKFS (Loudness, K-weighted, relative to Full Scale) appears in the ITU document and in the US broadcast standard ATSC A/85, where TV aims for −24 LKFS. LUFS is the EBU name. A meter reading −14 LKFS reads −14 LUFS.
Integrated, short-term and momentary LUFS
- Integrated LUFS: the whole track, with gating. This is the number platforms normalize to and the one people mean by “my master is at −10 LUFS”.
- Short-term LUFS: a sliding 3-second window. Shows how loud the chorus or the drop is.
- Momentary LUFS: a sliding 400 ms window, for quick changes.
- Loudness range (LRA): how much short-term loudness moves across the track, in LU. A dense, limited master has a small LRA; a dynamic one has a large LRA.
Why LUFS matters for your music
Spotify, YouTube, Apple Music and other services measure every track in LUFS and adjust playback so songs sit at a similar level. A master at −8 LUFS is turned down on Spotify by about 6 dB; one at −17 LUFS may be turned up on Spotify but stays quiet on YouTube. So the LUFS number decides how your track sounds next to everyone else’s. Targets for each service are in LUFS for Spotify, YouTube and other streaming services.
Tracks generated in Suno are a good example. One we measured came out at −16.1 LUFS integrated with a true peak of −3.7 dBTP, about 2 dB under the Spotify level and much quieter than commercial releases. You can check your own with the free LUFS meter.