RC Time Constant Calculator

Calculate the time constant (τ) of an RC circuit and determine capacitor voltage during charging and discharging.

Input Parameters

Enter values to calculate RC timing

Quick Guide

The RC Time Constant (τ):

τ = R × C

The time constant (Tau, represented by τ) describes the rate at which a capacitor charges or discharges through a resistor. It represents the time required for a capacitor to charge to approximately 63.2% of full voltage, or discharge to 36.8% of its initial voltage.

The 5τ Rule:

  • 1τ : 63.2% charged
  • 2τ : 86.5% charged
  • 3τ : 95.0% charged
  • 4τ : 98.2% charged
  • 5τ : 99.3% charged (Considered fully charged)