LUFS (Loudness Units relative to Full Scale) measures how loud audio sounds to people, not just how high its peaks reach. It is defined by the ITU-R BS.1770 standard and used by the EBU R128 broadcast rules, and it is the number Spotify, YouTube, Apple Music and other services use to play every track at roughly the same volume. 0 LUFS is the maximum a digital file can hold; finished music usually measures between −20 and −6 LUFS. LKFS is the same unit under another name.
How LUFS is measured
A LUFS meter does three things a simple level meter does not:
- K-weighting: before measuring, it filters the audio the way hearing does: it cuts deep bass, which we hear less of, and lifts the upper midrange, which we hear most.
- Averaging over time: it measures energy over a window rather than single samples.
- Gating: for the integrated value it ignores silence and very quiet passages, so a long fade-out or a pause doesn't drag the number down.
One LU (loudness unit) equals one decibel of level change. A track at −10 LUFS is 4 dB louder than one at −14 LUFS.
Integrated, short-term, momentary and LRA
| Measurement | Window | What it tells you |
|---|---|---|
| Integrated LUFS | The whole file | The overall loudness. This is the number streaming services normalize by. |
| Short-term LUFS | 3 seconds | How loud a chorus or a drop is. |
| Momentary LUFS | 400 milliseconds | The loudest hits. |
| Loudness range (LRA) | The whole file | How much the loudness varies, in LU. Pop masters often sit around 4–8 LU; film and classical much higher. |
| True peak (dBTP) | The whole file | The highest peak, including peaks between samples that appear on playback and encoding. |
LUFS vs dB, RMS and peak
- Peak (dBFS) is the highest sample. It says whether a file will clip, but almost nothing about how loud it sounds: a single snare hit can peak at 0 dBFS in a quiet song.
- RMS is an average level. It is closer to perceived loudness but treats all frequencies equally, so a bass-heavy track reads "louder" than it sounds.
- LUFS is RMS made to match hearing (K-weighted and gated). That is why two tracks at the same LUFS sound about equally loud, whatever their genre.
Loudness targets of streaming services
Services measure every track's integrated loudness when it is uploaded and adjust the playback volume so it lands near their target. These are the commonly published targets; services can change them, and listeners can switch normalization off.
| Platform | Target (integrated) | How it applies it |
|---|---|---|
| Spotify | −14 LUFS (Loud −11, Quiet −19) | Turns louder tracks down; turns quieter ones up only as far as their peaks allow. Asks for true peaks under −1 dBTP, or −2 dBTP for masters louder than −14 LUFS. |
| YouTube | −14 LUFS | Turns louder videos down; does not turn quieter ones up. |
| Apple Music | −16 LUFS | Sound Check, on by default. |
| Amazon Music | −14 LUFS | Normalizes playback. |
| Tidal | −14 LUFS | Normalizes playback. |
| Deezer | −15 LUFS | Normalizes playback. |
| Podcasts | −16 LUFS (stereo), −19 (mono) | The usual production target for spoken audio. |
| Broadcast TV | −23 LUFS (EBU R128, Europe), −24 LKFS (ATSC A/85, US) | Required by regulation. |
Spotify applies the adjustment during playback; it doesn't change your file. The web player and some third-party devices, such as TVs and speakers, don't normalize at all.
How loud should a master be?
There is no single right number, and "−14 LUFS" is a playback target, not a rule for masters. What normalization changes is the trade-off:
- Mastering louder than the target buys nothing on a normalizing service. A −8 LUFS master is turned down by 6 dB on Spotify and ends up as loud as a −14 LUFS master, but with less punch, because it was squashed to get there.
- A more dynamic master often sounds better after normalization: its drums keep their transients while the loud master's are flattened.
- Genre still matters. EDM, hip-hop and modern rock are commonly mastered between −10 and −7 LUFS for clubs, radio and listeners with normalization off. Acoustic, jazz and classical often sit between −18 and −14.
- Watch the true peak. Keep it at or below −1 dBTP (−2 dBTP for loud masters). Peaks above that can distort when the file is encoded to AAC, MP3 or Ogg.
A practical rule: master for the sound you want, check how much each service will turn it down, and make sure the peaks leave room for encoding.
The loudness war, briefly
From the 1990s to the 2010s, CDs and radio rewarded the loudest master: a louder track sounded "better" next to a quieter one. Producers compressed and limited music harder and harder, and some albums became famous for audible distortion. Loudness normalization on streaming services removed most of the incentive, since the loudest master no longer plays louder.
How to measure the LUFS of a song
The LUFS meter measures a file in the browser with an EBU R128 meter and shows integrated loudness, loudness range, true and sample peak, the loudest momentary and short-term values, and how much Spotify, YouTube, Apple Music and other services will turn it down. Drop a whole EP to compare its tracks; nothing is uploaded.
If a track is too quiet, the volume booster raises it to a loudness target while keeping peaks below the ceiling. For podcasts and voice recordings, clean up hiss and hum first with noise reduction, because raising the level raises the noise too.
FAQ
Is −14 LUFS loud?
It is moderate: quieter than most commercial pop and EDM masters (about −10 to −7 LUFS), louder than broadcast TV (−23 LUFS).
What is a good LUFS for Spotify?
Spotify recommends mastering around −14 LUFS integrated with true peaks under −1 dBTP. Louder masters are fine but are turned down, and should keep their true peak under −2 dBTP.
Is LUFS the same as dB?
A change of 1 LU equals a change of 1 dB, but LUFS measures perceived loudness over time, while dB values such as peak level describe single moments.
What is the difference between LUFS and LKFS?
None. Both names refer to the same ITU-R BS.1770 measurement; LKFS is used mainly in US broadcast standards.