RMS Voltage Calculator
Enter any one of the RMS, peak, peak-to-peak or average voltage of a sine wave and the calculator returns the other three. It uses the standard sinusoid relations where the peak is the RMS times the square root of two.
How to use the RMS voltage calculator
- Choose which voltage you want to enter.
- Type the value in volts.
- Read the RMS, peak, peak-to-peak and average values.
Examples
Peak of 170 V
vpeak = 170
vrms = 120.21 V, vpp = 340 V, vavg = 108.23 V
RMS of 120 V
vrms = 120
vpeak = 169.71 V, vpp = 339.41 V
Frequently asked questions
What is the RMS to peak formula for a sine wave?
The peak voltage equals the RMS times the square root of two, vpeak = vrms * sqrt(2). So 120 V RMS is about 169.7 V peak.
How do I get RMS from a peak voltage?
Divide the peak voltage by the square root of two, vrms = vpeak / sqrt(2). A 170 V peak gives about 120.2 V RMS, which is why a 120 V outlet peaks near 170 V.
What is peak-to-peak voltage?
Peak-to-peak is the full swing from the negative peak to the positive peak, vpp = 2 * vpeak. For a 170 V peak the peak-to-peak voltage is 340 V.
What does average voltage mean here?
It is the full-wave rectified mean, vavg = 2 * vpeak / pi, which is about 0.637 times the peak. The simple average of a full sine wave over a cycle is zero.
Does this only work for sine waves?
Yes. The square-root-of-two and 2 over pi factors are specific to a pure sinusoid. Square, triangle and distorted waveforms use different crest and form factors.
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