⚡ Capacitive Reactance Calculator
Calculate capacitor opposition to AC current
Example: 60 Hz (power line), 1000 Hz, 1 MHz
Enter in Farads (e.g., 1e-6 for 1 microfarad, 1e-9 for 1 nanofarad)
How to Use This Calculator
Enter Frequency
Input the frequency of the AC signal in Hertz (Hz). Common values: 60 Hz (US power), 50 Hz (European power), audio frequencies (20-20,000 Hz), radio frequencies (kHz-MHz).
Enter Capacitance
Input the capacitance value in Farads. Use scientific notation: 1e-6 for microfarads (μF), 1e-9 for nanofarads (nF), 1e-12 for picofarads (pF).
Calculate
Click the "Calculate Capacitive Reactance" button to get the reactance value in Ohms (Ω).
Formula
Xc = 1 / (2πfC)
Where:
- Xc = Capacitive Reactance (Ohms, Ω)
- f = Frequency (Hertz, Hz)
- C = Capacitance (Farads, F)
- π = Pi (approximately 3.14159)
Example Calculation:
For a 1 μF capacitor (1 × 10⁻⁶ F) at 60 Hz:
Xc = 1 / (2 × π × 60 × 1 × 10⁻⁶)
Xc = 1 / (3.77 × 10⁻⁴)
Xc = 2,653 Ω
Note: Capacitive reactance decreases with increasing frequency and capacitance. Higher frequencies pass through capacitors more easily.
About Capacitive Reactance Calculator
The Capacitive Reactance Calculator determines the opposition that a capacitor offers to alternating current (AC). Unlike resistance, which is constant, capacitive reactance depends on frequency and capacitance. This calculator is essential for designing AC circuits, filters, and understanding how capacitors behave in AC applications.
When to Use This Calculator
- Circuit Design: Calculate reactance for capacitor selection in AC circuits
- Filter Design: Design high-pass, low-pass, and band-pass filters using capacitors
- Impedance Matching: Determine capacitor values for impedance matching in RF circuits
- Power Factor Correction: Size capacitors for power factor correction in AC systems
- AC Analysis: Analyze AC circuits containing capacitive elements
Why Use Our Calculator?
- ✅ Quick Calculations: Instantly calculate reactance without manual computations
- ✅ Frequency Dependent: Understand how reactance changes with frequency
- ✅ Scientific Notation Support: Easily handle values in microfarads, nanofarads, and picofarads
- ✅ Free Tool: No registration or payment required
- ✅ Educational: Learn the relationship between frequency, capacitance, and reactance
Common Applications
AC Coupling: Calculate the reactance needed for coupling capacitors in audio amplifiers and signal processing circuits, where capacitors block DC while allowing AC signals to pass.
Power Factor Correction: Determine the capacitor size needed to improve power factor in industrial AC systems, reducing reactive power and energy costs.
RF Circuits: Design impedance matching networks and filters in radio frequency circuits, where capacitors are used to tune and filter signals at specific frequencies.
Tips for Best Results
- Higher frequencies result in lower reactance (capacitors pass high frequencies more easily)
- Larger capacitance values result in lower reactance
- Reactance is measured in Ohms (Ω), just like resistance
- Use consistent units: frequency in Hz, capacitance in Farads
- Remember: Xc = 1/(2πfC) - reactance is inversely proportional to frequency and capacitance
Frequently Asked Questions
What is the difference between reactance and resistance?
Resistance is constant and applies to both AC and DC circuits. Reactance only applies to AC circuits and varies with frequency. Capacitive reactance decreases as frequency increases, meaning capacitors pass high frequencies more easily.
Why does capacitive reactance decrease with frequency?
At higher frequencies, a capacitor has less time to charge and discharge in each cycle, so it offers less opposition to current flow. This is why capacitors are used in high-pass filters and AC coupling circuits.
What happens at DC (zero frequency)?
At DC (f = 0), capacitive reactance becomes infinite, meaning a capacitor acts as an open circuit and blocks DC current completely. This is why capacitors are used for DC blocking in circuits.
Can I use this for DC circuits?
No, capacitive reactance only applies to AC circuits. In DC circuits, after initial charging, a capacitor acts as an open circuit with infinite resistance.
How do I convert microfarads to Farads?
1 microfarad (μF) = 1 × 10⁻⁶ Farads. So 10 μF = 10 × 10⁻⁶ = 1 × 10⁻⁵ F. Use scientific notation: 10e-6 for 10 microfarads, 1e-9 for 1 nanofarad, etc.
What is the relationship between reactance and impedance?
Reactance is the imaginary part of impedance. For a pure capacitor, impedance Z = -jXc, where j is the imaginary unit. In circuits with both resistance and reactance, impedance combines both: Z = R + jX.