LUFS vs DBFS Explained Simply (Clearing Up The Confusion)

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  • Confused about metering?
  • Need a refresher on the differences between dBFS and LUFS?
  • Here are some tips to adhere to before submitting your mix for mastering

The difference between LUFS and DBFS isn’t the easiest to wrap your head around, but its certainly one that’s worthwhile.

In the age of endless streaming platforms and variable loudness specifications for delivery formats, there exists an endless confusion about metering, and consequently loudness.

This article is intended to help clear that up.

LUFS vs DBFS: What’s The Difference?

LUFS is a measurement of perceived loudness, whereas dBFS is a precise measurement of amplitude peaks in a digital signal.

dBFS is solely a measurement of electrical level, without human perceptual filters.

Each kind of metering serves a different purpose, and each was historically considered the most important at one time.

For the purpose of this article, peak and loudness meters will take precedence, as dBFS is a peak measurement and LUFS is a loudness measurement.

dBFS 

Almost all channels and busses within a DAW will provide a meter, and more often than not this is a full-scale peak meter, which measures the highest peaks in a signal in dBFS units.

In a digital system, dBFS is the unit of measurement for the amplitude levels or peaks, and the maximum value is defined as 0 dBFS.

dBFS, or decibels relative to full scale is, therefore, the most basic, common, and necessary measurement to understand.

But what is full scale?

Full scale is defined as the maximum voltage level possible before the overload of a data converter; in this case, an A/D converter or D/A converter.

Full scale is itself a variable; the actual full-scale voltage is defined by the internal converter design and thus can be a myriad of values.

To avoid clipping, the highest peak of your mix should not be 0dBFS but rather something below 0dBFS. Ideal peak levels are believed to be between -6dBFS and -3dBFS.

This difference between the highest peak level and 0dBFS is called the headroom.

Headroom

Headroom is an important target level for mix engineers, as it will help to maintain the dynamics of your mix during the mastering process.

Mastering engineers delicately raise the level and smooth the dynamics of your music for distribution on streaming platforms, but their magic cannot be worked unless there is headroom to do so!

Another common question asked is whether dBFS or RMS readings be used as loudness measurements?

Not quite, as loudness standards take into account human hearing and perception. Human perception doesn’t share a linear relationship to sound pressure level or full-scale measurements (more on this later).

They can, however, be used as a guide for improving your mixes!

K-System

The K-System is a metering and monitoring method invented by Grammy award-winning mastering engineer Bob Katz.

The K-System uses both RMS and peak meters in such a way that it helps to reduce the tendency to compress the dynamic range of your mix.

According to Katz, RMS levels correspond more closely with how we perceive loudness than any other quantifiable measurement of sound.

This is the key as it isn’t necessarily an accurate measurement of loudness.

LUFS

LUFS, or loudness units referenced to full scale, is the measurement that most accurately represents the human perception of sound. But why?

The human perception of sound is not linear. Although decibels are well suited to describing sound because they are based on a logarithmic function, decibels are a strict representation of the physics of sound rather than the anatomical understanding of sound perception.

Human Sound Perception

Human sound perception is governed chiefly by:

  • time
  • level
  • frequency
  • direction (in the case of acoustics)

LUFS is a measurement of loudness that considers the frequency spectrum and length of sounds in its reading of the loudness levels, thus taking into account the three main contributors to perception.

How is LUFS Measured?

LUFS can be measured in 4 ways:

  • Momentary Loudness
  • Short Term Loudness
  • Integrated Loudness
  • Loudness Range

Where momentary loudness and short-term loudness measure the loudness of the last 400ms and the last 3s respectively, integrated loudness and loudness range are measurements that consider the loudness over the duration of the mix.

Loudness Range (LRA) calculates the change in dynamic range throughout the mix by measuring and estimating the change in short-term loudness throughout the program.

Integrated Loudness, however, is key. Integrated LUFS identifies the total average volume of the material. Integrated Loudness is most often used for discussing target levels.

What is the Difference Between LUFS and LKFS?

Nothing, except the acronym. LKFS stands for Loudness, K-weighted, relative to full scale.

K-Weighting

Simply put, the K-Weighting is an indication that a K-weighted filter was applied to the measurement of the signal. AKA, the frequency and duration characteristics of human perception have been taken into account in the measurement.

The K-weighting filter is an essential part of a standard defined by The International Telecommunication Union: ITU 85.1770. 

K-Weighting is NOT to be confused with the K-SystemWhile these topics are related to loudness, they are not the same, as the K-System is not a loudness standard, nor is it a true loudness measurement.

Units

Loudness is measured in Loudness Units or LU. Loudness units represent an audible difference, making a change of even one LU perceptible.

Similar to the dB, LU is very rarely seen alone when describing a sound, as it represents a relationship rather than a value. For example, the difference between -16 and -24 LUFS is 8LU.

This article discusses LUFS, therefore specifying that the measurement is LU relative to full scale.

From our discussion of full scale above, we can assume that similar to dBFS, LUFS is measured in negative numbers, with 0 LUFS representing the maximum. 

LUFS Meters provide several benefits, these are mainly:

  • Removal of estimation in hitting targets 
  • Allow for ease of mixing in undesirable environments

The LUFS meter displays sound that we perceive as loud as very high; however, if the same sounds were displayed on a peak meter, the waveform would look very different.

By using the LUFS meter, you immediately know if you have hit your target – or not!

Additionally, judging levels and creating a balance when you’re mixing in a space that is not ideal, as you might when you are on location, will be much easier.

Your loudness meter tells you the actual loudness of all elements in the mix.

True Peak Reading

True Peak refers to an absolute maximum level of a signal and measures the peak levels and intersample peaks.

True Peak is measured in dBTP, a measurement that is also often included on LUFS meters.

dBTP is measured on the same scale as dBFS, but it is simply called dBTP since it is chiefly measured by the peak amplitude of a signal compared with the maximum that a device can handle before distortion occurs.

Essentially, the True Peak meter is there to ensure that your audio remains in tip-top shape; no distortion gremlins are allowed.

What is a Good Target LUFS level?

It depends on your platform of distribution! The good ol’ Loudness Wars left loudness standards in the dust – so almost every distribution platform is different.

  • -14 LUFS Amazon Alexa, Spotify Normal, Tidal, YouTube
  • -16 LUFS Apple, AES Streaming Service Recommendations
  • -16 to -18 LUFS Podcasts
  • -18 LUFS Sony Entertainment
  • -23 LUFS EU R128 Broadcast
  • -24 LUFS US TV ATSC A/85 Broadcast
  • -27 LUFS Netflix

Finally, these guidelines are important for you to follow because, if your LUFS measures above the standard for your distribution platform, your music WILL be automatically reduced in volume by the streaming algorithm.

This is done so that playlists have a more consistent average loudness for the user.

Summing Up 

dBFS provides a simple measurement of electrical level, whereas LUFS provides us with a greater tool: consistency.

This is, in fact, the key to all great mixes and albums – despite what the Loudness Wars stipulated (louder = better). 

Working with this new tool will be an adjustment, but be patient! Use this article as a guide to navigate the meter, which is the most obvious, and difficult, change.

Pretty soon, you’ll LUFS loudness meters as much as your mastering engineer – and they’ll LUFS you right back for having balanced, appropriately leveled mixes.