# Archived: What is Root Mean Square (RMS) Voltage?

This article has been archived and is no longer updated by National Instruments
**Hardware:** Multifunction DAQ (MIO)

**Problem:** What is the definition of root mean square (RMS) voltage?

**Solution:** Root mean square or RMS voltage is the voltage used for determining the amount of power that a sinusoidal signal is capable of providing. RMS voltage is defined as follows, where V

_{P} is the peak voltage in the AC or sinusoidal signal.

V_{RMS} = V_{P} / √2

Note that this equation is only valid for sinusoidal signals. Using the RMS voltage of a sinusoidal signal, you can determine the power provided by that signal using the following equation.

P = V_{RMS}^{2} / R

For example, standard North American wall outlets provide 120 VAC, which refers to the RMS voltage of the signal. Following the conversion, the peak voltage of the wall outlet is approximately 170 V.

**Related Links:** Developer Zone Measurement Terms: RMS
**Attachments:**
**Report Date:** 02/18/2003

**Last Updated:** 08/12/2014

**Document ID:** 2UHB61Q8