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RMS to Watts Converter

Convert an RMS voltage and load impedance into average power (watts), commonly needed for audio amplifier and speaker specifications.

V
Ω

What This Calculator Does

This tool converts an RMS (root mean square) voltage across a known load impedance into the average power delivered, expressed in watts. It’s commonly used for audio amplifiers, speakers, and general AC circuit calculations.

The Formula

Average power is calculated as P = Vrms² ÷ R, where Vrms is the RMS voltage and R is the load impedance in ohms. For a sinusoidal signal, the instantaneous peak power is twice the RMS (average) power, so Peak Power = 2 × Prms.

Why RMS Matters

RMS voltage represents the effective, continuous-equivalent value of an AC signal, which is why it’s used (rather than peak voltage) for calculating real average power delivered to a load. This calculator assumes a purely resistive load and a sinusoidal waveform; reactive loads or non-sinusoidal signals will differ. This tool is intended for general educational and planning purposes.

Last reviewed August 2026