Science & engineering
RC time constant calculator
Estimate ideal resistor-capacitor charging and discharging.
A clear answer. Here’s how.
Time constant τ = RC, converting kΩ to Ω and µF to F. For an initially uncharged ideal capacitor connected to a constant source, charge fraction = 1−exp(−t/τ). Discharge fraction from its initial voltage = exp(−t/τ).
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Resistance (kΩ)
- 10
- Capacitance (µF)
- 100
- Elapsed time (seconds)
- 1
Example result
- Time constant (seconds)
- 1
- Charging fraction of supply voltage
- 0.632120558829
- Discharge fraction of initial voltage
- 0.367879441171
- Elapsed time constants
- 1