Enter a positive capacitance value.
Enter a positive frequency value.
Capacitive Reactance Result
Quick Examples
Reactance vs. Frequency
See how the capacitive reactance of the selected capacitance changes across a range of frequencies.
Frequency Sweep
| Frequency | Frequency (Hz) | Capacitive Reactance | Reactance (Ω) |
|---|
Capacitive Reactance vs. Frequency
The chart uses logarithmic frequency spacing to show how capacitive reactance decreases as frequency increases.
How to Calculate Capacitive Reactance
Capacitive reactance describes the opposition that a capacitor presents to alternating current at a particular frequency.
The Capacitive Reactance Formula
Capacitive reactance is calculated using:
XC = 1 / (2πfC)
- XC = Capacitive Reactance in ohms (Ω)
- f = Frequency in hertz (Hz)
- C = Capacitance in farads (F)
- π ≈ 3.14159
How Frequency Affects Reactance
Capacitive reactance is inversely proportional to frequency.
- Higher frequency → Lower capacitive reactance
- Lower frequency → Higher capacitive reactance
- Higher capacitance → Lower capacitive reactance
- Lower capacitance → Higher capacitive reactance
How Capacitance Affects Reactance
For a given frequency, increasing the capacitance reduces the capacitive reactance.
For example, at the same frequency, a 1 µF capacitor generally has lower ideal capacitive reactance than a 100 nF capacitor.
Why Capacitive Reactance Matters
Capacitive reactance is important when analyzing AC circuits, filters, bypass capacitors, decoupling circuits, RF circuits and EMI suppression components.
It helps engineers estimate how a capacitor responds to signals at different frequencies.
Engineering Note: Ideal Capacitor vs. Real Capacitor
This calculator uses the ideal capacitor formula XC = 1 / (2πfC). Real capacitors may also be affected by equivalent series resistance (ESR), equivalent series inductance (ESL), package construction and self-resonant frequency (SRF). At frequencies near or above the self-resonant frequency, the actual impedance behavior may differ significantly from the ideal capacitive reactance.
Capacitive Reactance Examples
Examples of ideal capacitive reactance at different capacitance and frequency values.
| Capacitance | Frequency | Capacitive Reactance |
|---|---|---|
| 100 pF | 1 MHz | ≈ 1.59 kΩ |
| 1 nF | 1 MHz | ≈ 159.15 Ω |
| 10 nF | 1 MHz | ≈ 15.92 Ω |
| 100 nF | 1 MHz | ≈ 1.59 Ω |
| 1 µF | 1 kHz | ≈ 159.15 Ω |
| 1 µF | 1 MHz | ≈ 0.159 Ω |