Reatância Capacitiva
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
X_C = 1/(2πfC)
About this calculator
The capacitive reactance calculator determines the opposition a capacitor offers to alternating current, measured in ohms. The calculation uses the formula Xc = 1 / (2πfC), where f is frequency in hertz and C is capacitance in farads. This quantity is essential in AC circuits, influencing the behavior of filters, oscillators, and power supplies.
The calculator works simply: you enter frequency and capacitance values, and it applies the formula to obtain the reactance. For example, a 10 µF capacitor at 60 Hz results in approximately 265 ohms. Remember that capacitive reactance decreases with increasing frequency or capacitance, opposite to inductive reactance.
Use this tool when designing filter circuits, such as low-pass or high-pass, or when analyzing capacitor response in audio amplifiers and switching power supplies. It is also useful for sizing coupling or decoupling capacitors in electronic circuits.
Important precautions: ensure consistent units (hertz and farads). Capacitive reactance does not account for the equivalent series resistance (ESR) of the capacitor, which can be relevant at high frequencies. Also, the formula assumes an ideal capacitor with no dielectric losses.
Frequently asked questions
What is capacitive reactance?
It is the opposition a capacitor offers to alternating current, measured in ohms. It depends on frequency and capacitance.
How does frequency affect capacitive reactance?
The higher the frequency, the lower the capacitive reactance. At very high frequencies, the capacitor behaves like a short circuit.
Can I use this calculator for electrolytic capacitors?
Yes, but keep in mind that real capacitors have equivalent series resistance (ESR) which can alter behavior at high frequencies.
What is the difference between capacitive and inductive reactance?
Capacitive reactance decreases with increasing frequency, while inductive reactance increases. They oppose AC current in opposite ways.
How do I convert microfarads to farads?
Divide the microfarad value by 1,000,000. For example, 10 µF = 10 × 10⁻⁶ F = 0.00001 F.