Capacitor ESR Calculator

A simple calculator I made while learning about ESR and capacitor datasheets.

Reference Capacitance µF Dissipation factor (tan δ) ratio Reference frequency Hz Rated ripple current A RMS

High-frequency point Frequency kHz Rated ripple current A RMS Estimated ESL nH

Operating point

Ripple frequency 20 kHz kHz

Ripple current 750 mA RMS A RMS

ESR @ reference —

ESR @ operating point —

Estimated ESR @ HF —

|Z| @ operating point —

ESR ripple drop —

ESR loss —

Loss comparison rough estimate, not a rating —

Calculating…

Impedance |Z|, ESR, X_C, X_L Operating point

Bode phase Series RLC phase response Operating point

Formulas used

Reference ESR ESR_ref = tan δ / (2πf_refC)

High-frequency ESR estimate ESR_HF ≈ (I_ref² · ESR_ref) / I_HF²

Reactance X_C = 1 / (2πfC) X_L = 2πfL

Series impedance Z(f) = ESR(f) + j(X_L − X_C)

Magnitude and phase |Z| = √(ESR(f)² + (X_L − X_C)²) φ = atan2(X_L − X_C, ESR(f))

ESR loss and ripple drop P_ESR = I_ripple² · ESR(f) V_ESR = I_ripple · ESR(f)

ESR(f) is log-interpolated between the reference and high-frequency estimates. The HF point and comparison bar are estimates, not component ratings.