What is LUFS
Loudness is not just about how hard you “push it” in your DAW. LUFS is a unit that describes how loud we actually perceive a recording to be – and it is exactly this value that streaming platforms use when deciding what to do with your music once they receive it.
What LUFS actually means
LUFS stands for Loudness Units relative to Full Scale – in other words, a unit of loudness relative to the full scale of a digital signal. An equivalent abbreviation, used mainly in American terminology, is LKFS (K-weighted Loudness relative to Full Scale) – both mean the same thing and are interchangeable.
Unlike a simple peak value or an average RMS value, LUFS takes into account how human hearing perceives different frequencies and dynamics over time. The result is a number that is much closer to the real perception of loudness – which is why platforms such as Spotify and Apple Music use it as the basis for their normalisation algorithms.
LUFS is an absolute value – it tells you what loudness level a recording sits at relative to digital full scale (0 dBFS). A typical value for a loud pop master is around −7 LUFS, while a dynamic classical recording can easily be −24 LUFS.
LU (Loudness Unit) is a relative unit – the difference between two LUFS values. 1 LU equals 1 dB. So if a recording measures −9 LUFS and the target is −14 LUFS, the difference is 5 LU (the recording is 5 LU louder than the platform's target value).
Where LUFS came from – and why
The International Telecommunication Union (ITU) responded by publishing the ITU-R BS.1770 standard, which defined an algorithm for measuring integrated loudness. Based on this standard, the European Broadcasting Union (EBU) then issued the EBU R 128 recommendation, originally aimed at television and radio broadcasting.
Streaming platforms built on this foundation and started applying it to music distribution – each in its own way, but in principle it always comes down to measuring integrated loudness according to BS.1770 and bringing it closer to a target value. More detailed recommendations for internet streaming are summarised in a technical document from the Audio Engineering Society, AESTD1008.1.21-9 – Recommendations for Loudness of Internet Audio Streaming and On-Demand Distribution.
Four metrics LUFS gives you
Measuring LUFS involves several different types of values, each of which tells you something slightly different:
| Metric | Time window | What it measures and what it is for |
|---|---|---|
| Momentary LUFS | ~400 ms | The instantaneous loudness at a given moment. It reveals short-term fluctuations and is suitable for real-time monitoring while mixing. |
| Short-term LUFS | ~3 s | The average loudness over a short section. Good for monitoring the loudness of individual sections – verse, chorus, transition. |
| Integrated LUFS | Entire recording | The average loudness of the entire recording with quiet passages filtered out (gating). This is the value streaming platforms work with when normalising. |
| LRA (Loudness Range) |
Entire recording | The dynamic range of the recording – the difference between its quiet and loud sections. High LRA = wide dynamics (classical music), low LRA = heavily compressed sound. |
Tap the buttons above the chart to turn individual metrics on or off. Hover over (or tap) the curves to see the exact values at that point in time. The values have been adjusted for illustration.
When people talk about the “LUFS value” in the context of distribution or mastering for platforms, they almost always mean Integrated LUFS – the average loudness of the entire recording. The other metrics are useful when working in your DAW, but when platforms decide on normalisation, it is the integrated LUFS value that matters.
How the LUFS measurement algorithm works
Measuring LUFS is not a simple calculation of average amplitude. The ITU-R BS.1770 algorithm works in three steps:
What LUFS is used for in practice
Streaming platforms automatically compare the recordings that arrive in their system with a target loudness – and then handle them in one of two ways:
The recording is louder
If the distributed recording is louder than the platform's standard, the platform simply turns the signal down (downward normalisation). This does not degrade the sound in any way – the volume is simply reduced. It is therefore a completely safe transformation.
The recording is quieter
If the distributed recording is quieter than the platform's standard, the platform turns the signal up (upward normalisation). However, if the recording has too high a True Peak, turning it up can lead to limiting or distortion. This transformation can then be undesirable, because it may no longer be a simple gain increase – and it needs to be prevented during mastering.
Album normalisation
An album is normalised as a whole – this way, for example, the artistic intent behind the different loudness levels of the recordings on the album is not destroyed, where some recordings may be deliberately quieter and others louder. The target LUFS value is applied to the loudest recording on the album and the others are shifted by the same amount – preserving the original loudness balance across the recordings on the album.
Track normalisation
Each recording is also normalised to the target LUFS value on its own, regardless of the other recordings on the album. This normalisation is typically used when the recording plays in playlists, where recordings come from different artists – this way they will all have the same loudness level.
Loudness normalisation of recordings is carried out exclusively by the streaming platforms themselves on their side. Once the music is distributed, neither we at Bez Labelu nor you as the artist intervene in this process in any way – and neither of us can. Each platform has its own target values and its own implementation of normalisation.
What you can influence, however, is how you create and master the recording. More precisely, the point is to avoid situations where normalisation causes distortion. More on this in the article What LUFS and True Peak to aim for in digital distribution.
When and why to keep an eye on LUFS
LUFS is not a number you should aim for as a mandatory mastering output. It serves as information – it tells you where your recording stands relative to what the platforms expect, and helps you uncover potential problems before distribution.
Keeping an eye on LUFS makes sense especially when:
- You want to know how your recording is likely to behave after normalisation on the platforms – will it be turned down or turned up?
- You are releasing an album and want the songs to be balanced against each other (see album normalisation above).
- You have a recording with a very high True Peak and want to find out whether it risks distortion if a platform turns it up.
- You want to compare your master with reference recordings in your genre.
You can find out the LUFS value of your recordings in any DAW using specialised plugins (e.g. iZotope Insight, Sonnox Loudness, Waves WLM Plus), with standalone applications such as Youlean Loudness Meter, or on the web with online tools. A detailed overview of the tools is in the article How to measure the LUFS and True Peak of a recording. Alternatively, you can check the values straight away in our online LUFS and True Peak checker. When you upload to Artists Bez Labelu, Master check shows you the integrated LUFS and the True Peak after normalisation on individual platforms – you will see a short summary right in the recording form.