What Is RMS Level?
Updated October 2026
RMS, or root mean square, is the average level of a signal over a short time. It is a simple measure of how loud a sound feels, and it sits between the peak and the LUFS measure.
The short version
- RMS is an average level over a short window.
- Peak is the single highest sample; RMS is the average.
- LUFS weights the average to how people hear, which RMS does not.
- RMS is useful for a quick comparison of two clips.
The short definition
RMS measures the average power of a signal. It rises when the sound is steadily loud, and falls in quiet passages, so it is a fair guide to how loud a sound feels.
RMS, peak and LUFS
A peak meter shows the loudest moment. RMS shows the average. LUFS is a loudness measure that weights frequencies the way the ear does, so it matches perceived loudness better than RMS.
When to use it
For a quick check of two voice clips, RMS is simple and useful. For a final loudness target on a platform, use LUFS. The LUFS explanation covers the difference.
Measure loudness, not just peaks
The free LUFS meter on this site measures loudness; Tunedzy sets a voice to a target and checks the peak.
Free tools for this
Frequently asked questions
Is RMS the same as LUFS?
No. LUFS weights the average to how people hear.
Why does my peak meter show a low number but the file sounds loud?
The average is high while the peaks are moderate. That is what RMS and LUFS measure.
Which should I aim for?
For a platform target, LUFS.
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