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RMS Voltage Calculator

Convert sine-wave peak or peak-to-peak voltage into RMS voltage, with the supporting peak and peak-to-peak values shown beside the result.

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RMS voltage calculator: convert peak or peak-to-peak voltage for sine waves

An RMS voltage calculator converts sine-wave peak voltage or peak-to-peak voltage into RMS voltage and shows the related waveform values alongside the main result. It is useful when you need to compare oscilloscope amplitudes, signal-generator settings, or mains-style RMS ratings on a common basis.

What this RMS voltage calculator solves

This page starts from the two waveform values users most often have on hand: peak voltage and peak-to-peak voltage. In peak mode it divides by the square root of two to produce RMS voltage. In peak-to-peak mode it first derives the peak value and then applies the same RMS relationship.

Showing the supporting peak and peak-to-peak figures beside the answer keeps the conversion auditable. That matters when you are checking whether a measured waveform lines up with a datasheet rating or translating a bench measurement into the RMS value used by other equipment.

The sine-wave formulas behind the result

For an ideal sinusoidal waveform, RMS voltage equals peak voltage divided by the square root of two. Peak-to-peak voltage is twice the peak voltage, so dividing peak-to-peak voltage by two times the square root of two gives the same RMS result directly.

Those relationships are specific to sine waves. The calculator keeps the conversion modes separate so you can start from the quantity you actually know without having to work through the intermediate step manually.

Vrms = Vpeak / √2

Converts sine-wave peak voltage into RMS voltage.

Vpeak = Vpp / 2

Converts peak-to-peak voltage into peak voltage.

Vrms = Vpp / (2 x √2)

Direct sine-wave conversion from peak-to-peak voltage to RMS voltage.

How to use the result

RMS voltage is the effective value most often used for AC power discussions, multimeter readings, and equipment ratings. Peak and peak-to-peak values are more common on oscilloscopes, waveform generators, and signal descriptions.

Seeing all three quantities together helps prevent a common mistake: treating a measured crest value as though it were already an RMS rating. A 170 V peak sine wave, for example, corresponds to about 120.2 V RMS and about 340 V peak-to-peak.

Where this simplified model stops

This calculator assumes an ideal sinusoidal waveform only. It does not model triangle waves, square waves, clipped signals, crest-factor changes, DC offset, or harmonic distortion that changes the relationship among peak, peak-to-peak, and RMS values.

Use it as a planning and educational aid when the waveform is approximately sinusoidal. If the signal shape is intentionally non-sinusoidal or visibly distorted, calculate or measure RMS from the actual waveform instead.

Frequently asked questions

What is RMS voltage?

RMS voltage is the effective heating-equivalent value of an AC waveform. For a sine wave, it is the peak voltage divided by the square root of two.

 Why can I not use this for square or triangle waves?

Because the conversion factors on this page are specific to sine waves. Other waveform shapes have different relationships among RMS, peak, and peak-to-peak voltage.

 Why does the result also show peak and peak-to-peak voltage?

Those supporting values make it easier to compare the answer with oscilloscope readings, signal-generator settings, and equipment limits that may use a different voltage convention.

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