RC Circuit Calculator
Calculate time constant (τ) and cutoff frequency (fc)
How to Use This Calculator
Enter Resistance
Provide the resistor value in ohms (Ω). Example: 10000 for 10 kΩ.
Enter Capacitance
Provide the capacitor value in microfarads (µF). Example: 1 for 1 µF.
Calculate
Click Calculate to get time constant τ and cutoff frequency fc.
Formula
τ = R × C
fc = 1 / (2πRC)
Where:
- R = Resistance (Ω)
- C = Capacitance (F)
- τ = Time constant (s)
- fc = Cutoff frequency (Hz)
Example: R = 10 kΩ, C = 1 µF → τ = 10,000 × 1e-6 = 0.01 s (10 ms); fc ≈ 15.92 Hz.
About RC Circuit Calculator
This tool helps you quickly compute the time constant and cutoff frequency of RC circuits used in timing applications, filters, and analog electronics.
Common Applications
- Low-pass and high-pass filters
- Debouncing switches
- Timing circuits (charge/discharge)
- Analog signal conditioning
Tips
- Use quality capacitors for stable τ across temperature.
- Consider tolerance and leakage for long time constants.
- Ensure the load does not significantly affect R or C.
Frequently Asked Questions
Is this calculator for series or parallel RC?
These equations apply to the standard first-order RC network used as a filter: a single resistor and capacitor.
What if my capacitance is in nF?
Convert nF to µF by dividing by 1000, or multiply µF by 1000 to get nF. Enter the value in µF here.
Does tolerance affect results?
Yes. Component tolerances shift τ and fc. For precise timing, choose tight-tolerance components.