Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Rms Volts (V)

Required number input.

Rms Amperes (A)

Required number input.

Magnitude of earphone electrical impedance from RMS voltage and RMS current at the same sinusoidal test frequency. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Impedance Ohms (Ω)

The resulting impedance ohms returned as a number.

• Audio calculations must distinguish peak, RMS, dBu, dBV, acoustic SPL, electrical power, nominal impedance, sensitivity, and weighting. Loudspeaker impedance varies with frequency, room response changes SPL, and clipping or thermal limits are not represented by a single nominal value.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• Headphone Impedance

  Calculate headphone impedance magnitude at a test frequency from RMS terminal voltage and RMS current; phase is not determined.

• Peak to RMS Voltage Calculator

  Convert a sinusoidal peak voltage to its root-mean-square value, Vrms = Vp / sqrt(2); the RMS value produces the same heating in a resistor as the equivalent DC voltage.

• Ac Motor Reactive Power

  Calculate positive reactive-power magnitude for a balanced three-phase motor from line voltage, line current, and power factor.