What is LUFS Meter and How to Use it in Mastering

A LUFS Meter is a meter that measures, analyzes, and displays the LUFS levels of a piece of music or song. LUFS stands for Loudness Units Full Scale, and as opposed to measuring the highest levels of a song, it measures the average level of the whole piece giving you a far more useful reference to the overall loudness when mastering.

It is used in the final stage of mastering when engineers are making sure that the piece of music they are working on is optimized in level for whatever platform it is being mastered for. 

But how did it come about?

Metering has always been a critical part of both the recording and mastering process. But for some reason, probably because at its core, it is such a basic concept, many engineers seem to overlook it and think that it will sort itself out.

In the good old days, we used VU meters, and if you were really lucky, you might have had a red clip light as well. Although VU’s appear to lack accuracy, you would be surprised how good they were, and once you got the hang of using them, they were a very efficient way of getting the exact amount of gain you needed on a track.

For mastering, they were equally as good; however, when bar meters and digital metering came along, VU’s were seen as old-fashioned and out of date, and new measurement standards were needed.

Out with the old and in with the new

Two ways to measure audio levels were used, Peak and Root Mean Square (RMS). 

Peak is a measurement of the Peak or highest level that the audio produces, even if it only occurs for an incredibly short duration, such as a few milliseconds in an entire piece of music. RMS is a measurement of the average level (RMS level) over time which is similar to what you actually hear, the perceived loudness. 

When matching the levels of songs across an album, some engineers normalize every track to the maximum peak value or peak level. However, this is not usually effective because if one song has a higher average level than the others, it will sound louder. Other engineers normalize using RMS, but this could well cause peaks to go above 0, which is obviously not acceptable. 

Since both of these methods have their issues, a better standard was needed, and that was LUFS or Loudness Unit Full Scale.

The Loudness Wars

You just can’t get away from the simple fact that ‘if it’s louder, it sounds better.’ You can listen until your ears start turning blue, but in reality, unless you perfectly align a plug-in to be the exact same volume as the source signal, you just can’t make a judgment on whether it is making the sound better or worse.

This phenomenon has been used by the record industry to boost sales. If a mastering engineer can make their record sound louder than the one that was on before and after it when played on the radio, it would be perceived as being better and therefore sell more. This led to what became known as the Loudness Wars, with every engineer fighting to get their song louder than everyone else’s.

The art was in making the records as loud as possible without actually clipping. This involved the heavy use of compression and limiting, which massively decreased the dynamic range of the songs it was used on. This was also the case on TV, with corporations getting mastering engineers to do the same processes on adverts so that they had more of an impact due to the increased volume.

In terms of music, the stand-out example of taking this to the extreme was the Metallica album ‘Death Magnetic.’ It is an incredible piece of mixing and mastering but does it sound good? Is it comfortable to listen to? Most listeners don’t think so, and this was one of the reasons that thankfully led to the end of the infamous Loudness Wars.

Enough is enough

Boosting of levels and causing TV viewers to constantly turn their TV volume up and down while watching adverts did not go down well with the European Broadcast Union (EBU). They, therefore, decided to do something about it. 

However, in the process, they also made it far easier for us engineers to effectively get our songs to the exact levels for the platforms they will be played on and easier to match levels when we master an album of songs. The introduction of the EBU R128 standard changed mastering forever.

Loudness Unit Full Scale meter

LUFS or Loudness Unit Full Scale references the Loudness Units to full scale, which is the maximum level a system can handle. This allows us to use loudness meters whose capabilities are far greater than traditional VU or Peak Meters. The majority of all commonly used DAW software now include this as a metering option.

Loudness Units are a unit of measurement that quantifies a piece of music’s perceived loudness by measuring the average level over time, which is termed integrated loudness. This, in theory, means that two pieces of music with identical LUFS readings should sound as if they are at the exact same level, and this is usually the case in practice. 

Therefore, mastering effectively using LUFS readings will guarantee consistent levels across different tracks or an album.

What is a good LUFS level?

Broadcasters such as YouTube decide on a standard LUFS level so that viewers don’t have to constantly change the volume. They then adjust all audio on any of their videos to hit their decided LUFS level. 

This means that you can still squash your tracks as much as you like to produce a reading of -5 LUFS, but YouTube will just convert it to -13 LUFS so that it’s at the same volume level as every other video. However, due to the squashing process, it will have less of a dynamic range which will not make it as dynamically interesting to most listeners.

Alternatively, if you’re mastering a jazz song with a wide dynamic range that registers at -18 LUFS, the level will be increased to -13 LUFS. 

But what about TV?

For broadcast, the recommended level is -23 LUFS.

What LUFS should I master to?

This varies from platform to platform, as well as particular broadcasters changing their standards over time. At the current time they are:

• Apple Music = -16 LUFS
• Amazon Music = -9 to -13 LUFS
• Apple Podcasts = -16 LUFS
• Spotify = -14 LUFS
• Spotify Loud = -11 LUFS
• Deezer = -14 to -16 LUFS
• Soundcloud = -8 to -13 LUFS
• Youtube = -13 to -15 LUFS
• CD = -9 LUFS
• Live Club Play = -6 to -9 LUFS

How many dB is LUFS?

Although they have different names, they are, in fact, exactly the same. LUFS is the newer standard for measuring average loudness and is considered the most accurate. However, in all practical applications, one Loudness Unit is equal to one Decibel.

Final Thoughts

LUFS metering has changed the way we master music for the better. It is simple to use and understand, plus the results you can achieve with it will take your mastering skills to the next level.

In terms of what I use, my preferred LUFS meter is the Izotope Insight 2. I find it has all the functionality I need while still being very easy to use.

But don’t forget that you can master at whatever LUFS level you want. In fact, many top engineers believe that starting off trying to achieve a specific LUFS number or target loudness is not recommended. Therefore, master to a level that sounds good to you, without being overly concerned about metering. 

After you achieve something that you like the sound of, analyze it to find out where it is on the LUFS scale and then fine-tune it for whatever platform you are mastering for.