Electrical fundamentalsMVP
RC time constant
Time constant and −3 dB cutoff frequency of a single-pole RC network.
Inputs
Result
Enter values and calculate to see the result.
Interpretation
Enter the resistance and capacitance of a single RC stage.
Formula
τ = R · C , f_c = 1 / (2π R C)
Charge/discharge time and the corresponding filter corner.
Variables
| Symbol | Variable | Unit |
|---|---|---|
| τ | Time constant | s |
| f_c | Cutoff frequency | Hz |
| R | Resistance | Ω |
| C | Capacitance | F |
Assumptions & validity
This tool assumes:
- Ideal single-pole RC (one resistor, one capacitor); no parasitics.
- τ is the 63.2% charge/discharge time; f_c is the −3 dB corner.
Worked example
R = 1 kΩ, C = 1 µF.
τ = 1000 Ω × 1×10⁻⁶ F = 1 ms; f_c = 1/(2π·1 ms) ≈ 159 Hz