Time Constant Calculator
This calculator is used for calculating Tau time constants in a series RC or R/L circuit, the percent of change of the Capacitor or Inductor after the given amount of time, and the voltage of the Capacitor or Inductor after the given amount of time.Enter the value of Resistance, either the Inductance Or Capacitence, the Initial Voltage, and the amount of time in seconds.

Enter Resistance (ohms)

Enter Capacitence (Farads)
or Enter Inductance (Henrys)

Initial Voltage (volts)
Time (seconds)


τ (Tau Time Constant):
Percentage of Charge:
Final Voltage (volts):
An example (and test) of the formula is to use 100 ohms, 0.1 Farad, 12 volts, and 1 second. The results should be: Tau=10, Percent of Charge=9.51625819640405, and Final Voltage=1.1419509835684858.