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Peak-to-Peak Voltage Calculator

Vpp and Vrms in volts for a sine wave of a given peak voltage.

How it is calculated

You enter the amplitude, meaning the peak voltage measured from the zero line to the top of the wave, in volts. The tool applies Vpp = 2 × Vpeak and Vrms = Vpeak ÷ √2, where √2 ≈ 1.4142. Both results are shown in volts with two decimals. The RMS formula is valid for a pure sine wave only; a square, triangle or distorted wave has a different ratio between peak and RMS. The doubling for Vpp assumes the wave swings equally above and below zero, so a signal with a DC offset needs separate treatment. A negative amplitude returns no result because amplitude is a magnitude; zero returns 0.00 V for both outputs.

Worked example

Suppose a sine wave has a 170 V amplitude. Peak-to-peak is 2 × 170 = 340.00 V. For RMS divide by √2: 170 ÷ 1.4142 = 120.21 V. So a signal that swings 340 V from bottom to top delivers the same heating power as a steady 120.21 V DC source, which is the figure power ratings are quoted in.

Try this example →

Common mistakes

  • Typing the peak-to-peak reading from a scope into the amplitude field. The field wants the half-swing (zero to peak), so enter half of what you measured.
  • Assuming RMS equals peak ÷ √2 for any waveform. That ratio holds for sine waves; for a square wave RMS equals the peak, so the RMS result here would be wrong.
  • Ignoring DC offset: if the wave is centred at 2 V rather than 0 V, the swing is still 2 × the amplitude about its own centre, not 2 × the highest voltage on the screen.
  • Comparing a Vpp figure to an RMS rating (such as a mains or speaker spec) without converting, which is off by a factor of about 2.83.
  • Entering a negative amplitude to represent the bottom of the wave; the tool rejects negatives, so enter the positive magnitude.

Sources

About this calculator

Peak-to-peak voltage (Vpp) is the total swing of a waveform from its most positive point to its most negative point, so for a symmetric signal Vpp = 2 × Vpeak. For a sine wave, the RMS value — the equivalent steady voltage that would deliver the same power — is Vrms = Vpeak / √2 = Vpp / (2√2).

Electrical and audio engineers read peak-to-peak values directly off an oscilloscope trace to check signal swing against a component's voltage limits, while RMS values are what power calculations, amplifier specs, and AC mains ratings actually use — so converting between the two is a routine step whenever a datasheet or a scope screen speaks a different language than the spec you're checking against.

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Comments (1)

  • Editorial team

    This tool starts from the amplitude, so if an oscilloscope shows you the peak-to-peak value, halve it before entering. For a sanity check with mains, a 230 V RMS supply has a peak of about 325.27 V; typing 325.27 gives roughly 650.54 V peak-to-peak and an RMS of 230.00 V. Remember the RMS line assumes a sine wave. Which waveforms do you measure most often?

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