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 (MHz)

Required number input.

Capacitance (µF)

Required number input.

Compute the ideal impedance magnitude of a decoupling capacitor as Z = 1/(2 x pi x f x C), expressed in milliohms. 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 (mΩ)

The resulting impedance 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.

• Ideal Capacitor Impedance

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

• Decap Resonance

  Compute the resonant frequency in megahertz of a decoupling capacitor from its mounted series inductance in nanohenries and capacitance in nanofarads.

• EMI Capacitor Reactance

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