Reactance Calculator (XL, XC)

Calculates the opposition to AC current flow from inductors and capacitors. Inductive reactance increases with frequency, while capacitive reactance decreases with frequency. Worked example: a 10 uF capacitor at 50 Hz has XC = 1/(2 pi x 50 x 10e-6) = 318 ohm; at 100 uF it falls to 31.8 ohm - bigger capacitors pass AC more easily. The crossover point matters in audio: a 4 ohm speaker with a 10 uF capacitor crosses at f = 1/(2 pi x 4 x 10e-6) = 3.98 kHz, exactly the first-order high-pass design equation in daily use.

1. 1

   Step 1

   Select reactance type (inductive or capacitive)

2. 2

   Step 2

   Enter the component value (L or C)

3. 3

   Step 3

   Enter the AC frequency

4. 4

   Step 4

   View the calculated reactance in ohms

• 1

  Inductive reactance: XL = 2πfL (increases with frequency)

• 2

  Capacitive reactance: XC = 1/(2πfC) (decreases with frequency)

• 3

  At resonance, XL = XC

• 4

  Reactance is measured in ohms like resistance

• Confusing reactance with impedance (Z includes R)

• Forgetting the negative sign for capacitive reactance in calculations

• Using DC component values at high frequencies

• Not converting units (mH to H, µF to F)