Capacitor Discharge Calculator

Theoretically, a capacitor never fully discharges to zero volts, as the exponential curve only approaches zero but never reaches it. However, for practical purposes, a capacitor is considered fully discharged after 5 time constants (5τ). At this point, it has discharged to less than 1% of its initial voltage.

A very low resistance results in a very small time constant (τ = R × C). This means the capacitor will discharge extremely quickly. In the extreme case of a short circuit (R ≈ 0), the discharge is nearly instantaneous, which can create a very high current spike, potentially damaging the capacitor or other circuit components.

While the time constant (τ) is the same for both charging and discharging, the voltage formula is different. The charging formula is V(t) = V₀(1 - e^-t/RC), where V₀ is the source voltage. This calculator is specifically designed for the discharge process.