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.

Frequency (Hz)

Required number input.

Capacitance (F)

Required number input.

Calculate ideal capacitive reactance Xc=−1/(2πfC) and its magnitude in ohms. ESR, ESL, leakage, and self-resonance are not included. 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]

Reactance ohm

The resulting reactance ohm returned as a number.

Magnitude ohm

The resulting magnitude ohm returned as a number.

• Capacitance, ESR, leakage, ripple rating, lifetime, and self-resonance vary with frequency, temperature, DC bias, aging, dielectric, package, and mounting. Nominal capacitance alone does not determine in-circuit impedance or reliability.
• 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.

• EMI Capacitor Reactance

  Calculate the magnitude of ideal capacitor reactance 1/(2πfC) from positive frequency and capacitance, ignoring ESR and parasitics.

• EMI Inductor Reactance

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• Common-Mode Choke Impedance

  Estimate one winding's series RL impedance magnitude at frequency f as √[R²+(2πfL)²]. Enter the effective common-mode inductance and resistance at the operating point; real choke impedance also includes core loss, capacitance, and self-resonance.