RMS (root mean square) voltage is the effective value of an AC voltage — the equivalent DC voltage that would deliver the same average power to a resistive load. For a 120 V RMS mains supply, the peak voltage is about 170 V.

How is V_rms calculated for a sine wave?

For a pure sine wave, V_rms = V_peak / sqrt(2) ≈ V_peak × 0.7071. Equivalently, V_rms = V_pp / (2 × sqrt(2)) ≈ V_pp × 0.3536.

Why does waveform shape matter?

Different waveforms have different crest factors (V_peak / V_rms). A square wave has a crest factor of 1 (V_rms = V_peak), a triangle wave is 1/sqrt(3) ≈ 0.5774 × V_peak, and a sawtooth is the same as a triangle. Choosing the wrong shape gives an incorrect RMS result.

What is peak-to-peak voltage?

Peak-to-peak voltage (V_pp) is the total voltage swing from the negative peak to the positive peak of a waveform. For a symmetric waveform, V_pp = 2 × V_peak.

What is the crest factor?

The crest factor is the ratio of V_peak to V_rms. A lower crest factor means the waveform is more efficient at delivering power. A square wave (crest factor = 1) is the most efficient; a sine wave has a crest factor of sqrt(2) ≈ 1.414.

RMS Voltage Calculator

Name: RMS Voltage Calculator
Availability: InStock
Author: Nham Vu

Convert between peak, peak-to-peak, and RMS voltage for common AC waveforms instantly.

Input

Waveform Type

Known Voltage

Voltage Value

Results

Enter a voltage value to see results.

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