RMS Voltage Calculator | Calculate Effective AC Voltage with Waveform Analysis


The RMS Voltage Calculator is a tool used to calculate the Root Mean Square (RMS) voltage of an alternating current (AC) waveform. The RMS voltage represents the effective voltage of an AC signal and is commonly used in electrical engineering and physics. This calculator helps users determine the RMS voltage by taking into account various parameters such as waveform shape, characteristic voltage measurements, voltage, and wave offset.


The RMS Voltage Calculator is useful in various applications, including analyzing AC circuits, designing electrical systems, and evaluating the power delivered by an AC source. It provides a quantitative measure of the voltage in AC systems, which is crucial for assessing power consumption, load capacity, and the overall performance of electrical devices.


  • Waveform Shape: The waveform shape refers to the specific pattern that the AC signal follows over time. Common waveform shapes include:

    • Sine Wave: Represents a smooth oscillation with a symmetrical shape.

    • Square Wave: Exhibits a rapid transition between high and low voltage levels.

    • Triangle Wave: Displays a linear increase and decrease in voltage.

    • Sawtooth Wave: Resembles a sawtooth pattern with a sharp rise and gradual decline in voltage.

    • Half-wave rectified sine wave: This waveform shape occurs when only the positive (or negative) half of a sine wave is allowed to pass, while the other half is blocked. This results in a waveform that resembles a series of half-cycles.

    • Full-wave rectified sine wave: This waveform shape occurs when both the positive and negative halves of a sine wave are allowed to pass, resulting in a waveform that includes complete cycles.

  • Characteristic Voltage: The characteristic voltage refers to the specific measurements associated with the waveform shape. These measurements may include:

    • Peak Voltage (Vp): The maximum amplitude or highest voltage reached by the waveform.

    • Peak-to-Peak Voltage (Vpp): The difference between the maximum and minimum voltage points in one complete cycle.

    • Amplitude (A): Half the peak-to-peak voltage or half the difference between the maximum and minimum voltage points.

    • Average Voltage (Vavg): The average value of the waveform over one complete cycle.

  • Voltage (V): This parameter represents the instantaneous voltage value at a specific point in time within the AC waveform.

  • Wave Offset (V₀): The wave offset represents a DC voltage component added to the AC waveform. It indicates a shift of the entire waveform vertically, either above or below the zero voltage line.

Math Equations:

  • Calculation of RMS Voltage (Vrms): The RMS voltage is calculated using the following equation, which takes into account the instantaneous voltage values across one complete cycle of the waveform:

    Vrms = sqrt((V₁² + V₂² + V₃² + ... + Vn²) / n)


    • V₁, V₂, V₃, ..., Vn represents the individual instantaneous voltage values.
    • n represents the total number of voltage samples taken over one complete cycle of the waveform.
  • Relationship between RMS Voltage and Peak Voltage for a Sine Wave: For a sine wave, the RMS voltage (Vrms) can be related to the peak voltage (Vp) using the following equation:

    Vrms = Vp / √2

    This equation holds true for a sine wave, where the ratio of RMS voltage to peak voltage is always √2 or approximately 0.707.

Note: The specific mathematical equations may vary depending on the waveform shape and the characteristics of the voltage measurements. The provided equations are suitable for a sine wave and can be adapted accordingly for other waveform shapes.


It is believed that these calculations are accurate, but not guaranteed. Use at your own risk!