If you have worked with audio meters, you have probably encountered both RMS and LUFS.
They are related, but they should not be treated as interchangeable measurements.
What is RMS?
RMS stands for Root Mean Square. It provides a mathematical representation of the average energy of an audio signal over a defined period.
What is LUFS?
LUFS is a standardized loudness measurement designed to better represent perceived programme loudness.
Modern loudness standards use LUFS because human hearing does not perceive every frequency and signal characteristic equally.
Why does LUFS matter for streaming?
Streaming normalization is based around perceived loudness rather than simply the raw electrical energy represented by an RMS measurement.
This makes LUFS a more useful measurement when discussing overall programme loudness for distribution.
Does RMS still matter?
Yes. RMS can still provide useful information about signal energy and density, particularly when used alongside other measurements.
Use both measurements for context
Instead of asking which meter is better, consider what question you are trying to answer.
- LUFS: useful for programme loudness.
- RMS: useful for signal energy and density.
- True Peak: useful for peak safety.
- PLR: useful for peak-to-loudness context.
No single meter can completely describe a master.
LoudCheck reports both integrated LUFS and RMS-based measurements as part of its audio analysis.