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Peak-to-Peak Voltage Calculator

Convert RMS or peak voltage to peak-to-peak on a sine. Vpp = 2 × Vpeak = 2√2 × Vrms. Default 120 V RMS gives about 339.4 V peak-to-peak. Informational only.

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How to use peak-to-peak voltage calculator

  1. Type RMS, peak, or peak-to-peak. Leave the values you want solved blank.
  2. Assume a symmetric sine unless you know the wave is offset.
  3. Read all three amplitude forms in the result rows.
  4. Informational only. Nothing is uploaded.

Peak-to-peak voltage

Full sine swing

Peak-to-peakDistance from negative peak to positive peak
PeakHalf of peak-to-peak on a centered sine
RMSVrms = Vpp / (2√2) on a sine
Scope useOscilloscopes often display Vpp directly
120 V lineAbout 339 V peak-to-peak for 120 V RMS sine
Scope noteInformational. Not instrument calibration.

Peak-to-peak from RMS

Vpp = 2 × Vpeak = 2√2 × Vrms. For 120 V RMS, Vpp ≈ 339.41 V. If you measure Vpp on a scope, peak is Vpp / 2 and RMS is Vpp / (2√2).

Reading scopes

Many scopes default to peak-to-peak in the vertical readout. Compare that readout to the RMS your multimeter shows on the same sine to see the √2 and factor-of-two relationships this page prints.

DC offset warning

If the sine rides on a DC level, peak-to-peak still spans the trace height but peak relative to zero is not half of Vpp unless the wave is centered. This calculator assumes no DC offset.

Limits

Ideal sine only.

The formula runs in this tab. CZNull does not receive the numbers.

Informational only. Not wiring, code, or manufacturer approval. See the disclaimer.

What is peak-to-peak for 120 V RMS?
About 339.4 V peak-to-peak: Vpp = 2√2 × 120 V on a centered sine.
How do I get peak from peak-to-peak?
Divide Vpp by 2 on a symmetric sine. The page does that when you enter only Vpp.
Why do scopes show peak-to-peak?
It matches the full vertical deflection of the trace, which is easy to read against graticule divisions.
Is Vpp double the peak voltage?
Yes for a wave centered on zero. Peak is one half of the peak-to-peak span.
Can I use this for triangle waves?
No. Triangle and square waves have different peak-to-RMS ratios. This URL is for sinusoids only.