Calculate peak voltage from RMS sine or full-wave rectified average voltage, or find the reverse in V, mV, or kV with step-by-step results.

Peak Voltage Calculator

Enter a value in either field to calculate the other.





Peak Voltage Formula

Peak voltage is the highest instantaneous value reached by a voltage waveform. For a pure sine wave, you can calculate it directly from either RMS voltage or average voltage.

Known Value Relationship Use When
RMS voltage
Vₚ = V₍RMS)√(2)
 You know the AC RMS value of a sinusoidal waveform.
Average voltage
Vₚ = V₍avg)(π) / (2)
 You know the rectified average value of a sine wave.

Related Sine-Wave Conversions

Conversion Formula
Peak from RMS
Vₚ = V₍RMS)√(2)
RMS from peak
V₍RMS) = (Vₚ) / (√(2))
Average from peak
V₍avg) = (2Vₚ) / (π)
Peak-to-peak from peak
Vₚₚ = 2Vₚ
Crest factor for a sine wave
(Vₚ) / (V₍RMS)) = √(2)

Variable Definitions

Symbol Meaning Typical Unit
Vp Peak voltage, measured from zero to the waveform crest V, mV, kV
VRMS Root-mean-square voltage, the effective AC value V, mV, kV
Vavg Average rectified voltage of a sine wave V, mV, kV
Vpp Peak-to-peak voltage, from negative peak to positive peak V, mV, kV

How to Calculate Peak Voltage

  1. Choose whether your known input is RMS voltage or average voltage.
  2. Enter the value into the calculator using the correct unit.
  3. Select the matching mode:
    • RMS if the input is VRMS
    • Average if the input is Vavg
  4. Read the result as the waveform’s peak voltage.

Common Peak Voltage Values

Known Value Type Peak Voltage Peak-to-Peak Voltage
5 V RMS 7.07 V 14.14 V
12 V RMS 16.97 V 33.94 V
24 V RMS 33.94 V 67.88 V
120 V RMS 169.7 V 339.4 V
230 V RMS 325.3 V 650.6 V

Important Notes

  • The RMS and average formulas above are valid for a sinusoidal waveform.
  • Average voltage here means the rectified average of a sine wave, not the full-cycle average. A full sine wave averaged over one complete cycle is 0 V.
  • For square, triangle, clipped, or distorted waveforms, the conversion factors are different.
  • Peak voltage is critical when selecting capacitors, diodes, insulation, probes, and power components that must survive the highest instantaneous voltage.

Where Peak Voltage Is Used

  • AC power analysis
  • Oscilloscope waveform interpretation
  • Rectifier and filter design
  • Capacitor voltage rating checks
  • Insulation and component stress calculations
  • Signal and audio electronics

Quick Comparison: RMS vs Peak vs Peak-to-Peak

Measurement What It Represents
RMS The effective heating or power-equivalent value of AC voltage
Peak The maximum voltage above zero at the crest of the wave
Peak-to-peak The total swing from the negative peak to the positive peak