Capacitive Reactance Calculator

Calculate capacitive reactance and AC impedance for capacitors in alternating current circuits

Calculate Capacitive Reactance

Choose between linear frequency (Hz) or angular frequency (rad/s)

Capacitance of the capacitor

AC frequency of the signal

Capacitive Reactance Results

0.000
milliohms (mΩ)
0.00
ohms (Ω)
0.000000
kiloohms (kΩ)
0.000000000
megaohms (MΩ)
0.00 Ω
Impedance Magnitude
|Z| = Xc (pure capacitor)
-90°
Phase Angle
Current leads voltage
0
Power Factor
cos(φ) for pure capacitor
0.000 rad/s
Angular Frequency
ω = 2πf
0.000 μs
Time Constant (RC)
τ = RC (with 1kΩ resistor)

Formula used: Xc = 1 / (2π × f × C) = 1 / (ω × C)

Input values: C = 0.000e+0 F, f = 0.000 Hz

Impedance: Z = -jXc = -j0.00 Ω (complex form)

Reactance Analysis

Example Calculations

Audio Coupling Capacitor

Capacitance: 10 μF

Frequency: 1 kHz (audio signal)

Calculation: Xc = 1 / (2π × 1000 × 10×10⁻⁶) = 15.92 Ω

Application: Low impedance for audio frequencies

Power Line Filter

Capacitance: 100 nF

Frequency: 60 Hz (power line)

Calculation: Xc = 1 / (2π × 60 × 100×10⁻⁹) = 26.53 kΩ

Application: High impedance blocks low-frequency noise

Frequency Effects

DC

f = 0 Hz

Xc = ∞

Open circuit (no current flow)

LF

Low Frequency

High Xc

Blocks low frequencies

HF

High Frequency

Low Xc

Passes high frequencies

f → ∞

Xc → 0

Short circuit at very high frequencies

Circuit Applications

🔊

AC Coupling

Blocks DC, passes AC signals

🔧

High-Pass Filter

Passes high frequencies, blocks low

Power Factor Correction

Compensates inductive loads

🎛️

Timing Circuits

RC time constants

Understanding Capacitive Reactance

What is Capacitive Reactance?

Capacitive reactance (Xc) is the opposition that a capacitor offers to alternating current (AC). Unlike resistance, which opposes both AC and DC, reactance only affects AC signals. The reactance decreases as frequency increases, making capacitors frequency-dependent components.

Key Properties

  • Frequency dependent: Xc ∝ 1/f
  • Phase shift: Current leads voltage by 90°
  • No power loss: Reactive component only
  • Units: Ohms (Ω), same as resistance

Reactance Formulas

Xc = 1 / (2πfC)

Xc = 1 / (ωC)

Xc: Capacitive reactance (Ω)

f: Frequency (Hz)

ω: Angular frequency (rad/s)

C: Capacitance (F)

Complex Impedance

Pure capacitor: Z = -jXc

RC circuit: Z = R - jXc

Magnitude: |Z| = √(R² + Xc²)

Phase angle: φ = -arctan(Xc/R)

Applications: AC coupling, filtering, power factor correction, timing circuits, reactive power compensation