The Loudness War has had countless musicians wanting their music louder and to a fault in many cases (including a good chunk of my audio mastering clients at Music Guy Mastering), begging the question what is the best RMS level for mastering. Let’s talk where you should aim for when it comes to the RMS level, including a quick reminder of what this level represents and how it differs from other measurements on loudness.
What is RMS
As I mentioned in my recent overview of what is RMS in audio, RMS stands for Root Mean Square.
The math behind calculating RMS essentially means you square every sample of the audio you want to calculate it for, take the mean of that, then take the square root of the mean.
In practical terms, RMS is a representation of the average amount of dynamic range in your audio.
Dynamic range in audio refers to the difference between the quietest and loudest instances of the practical parts of the audio.
Dynamic range is important to keep in your audio because it sounds more natural, not to mention it keeps your listener’s ears more engaged.
This is in contrast to a fat sausage of audio where the song stays virtually the same volume for the duration, causing ear fatigue and losing the interest of your listener.
With that recap of dynamic range in mind, a “higher” RMS number (-14 for example) refers to more dynamic range, but of course this equates to a quieter average volume.
Conversely, a “lower” RMS number (-6 for example) refers to less dynamic range, meaning it’s louder more often, or in other words equating to a louder average volume.
What is the Best RMS Level for Mastering
Let’s get back to the initial topic/question: what is the best RMS level for mastering.
As I mentioned in the aforementioned article where I provided an overview of RMS, this will generally vary from genre to genre.
Some genres are known for sacrificing dynamic range for the sake of a louder, more in your face mix/master like EDM.
Some genres like Pop do it because the Loudness War still rages on, so having a louder song is perceived as being necessary to be competitive with your peers in addition to writing and producing the best song you can.
Conversely, you have genres like jazz or even orchestral music which on balance aren’t nearly as concerned with volume and value dynamic range more because the music benefits from alternating between quiet and loud moments for the reasons mentioned above.
Ultimately if you’re concerned with matching or near matching the loudness of your mix or master to a number, you’re much better suited in going by LUFS rather than RMS.
As I mentioned in my comparison of RMS vs LUFs, LUFs are a representation of the average overall PERCEIVED volume of a piece of music. This makes LUFS the most practical way of measuring volume.
Incidentally the most popular audio streaming services today like Spotify and Apple Music recommend upload targets by LUFs rather than RMS.
I even covered the exact values to aim for in my overview of what LUFs to master to:
Check that tutorial out because in it I offer up a free tool for checking the LUFs of your audio which you can download and easily use to get a quick reading.
As you can see or what you might ultimately discover from the image above, the levels aren’t nearly as loud as you’ve likely been ultimately setting the volume of your mixes or masters to.
Thankfully today there’s far less reason to compress your audio’s dynamic range to death for the sake of volume because Spotify, Apple Music, and all the rest normalize your audio by default for most listeners with a default feature which ensures every song plays at the same volume so listeners don’t have to adjust their volume between songs on a playlist.
That’s not to say that I aim for -14 LUFS whenever I bounce a master, so refer to that for more information on ultimately finding the best level for YOUR finished master (not to mention let me get my obligatory plug for offering to let ME master your music via my sister site, Music Guy Mastering, where you can get a free test master today).