Capacitor Discharge Calculator

Online Calculator and Formulas to calculate the Capacitor Discharge at a Specified Time

Calculate the discharge voltage

On this page you can calculate the discharge voltage of a capacitor in a RC circuit (low pass) at a specific point in time.

In addition to the values of the resistor and the capacitor, the original input voltage (charging voltage) and the time for the calculation must be specified

The result shows the charging voltage at the specified time and the time constant τ (tau) of the RC circuit. The capacitor is discharged approx. 99.33% after a period of 5 τ. This means that at specified times, well over 5 τ the charging voltage is close to zero.

Calculate discharge voltage

Input voltage U0
Discharge time
Decimal places
Time constant
Charging voltage
Discharge current

If you move the mouse over the graphic, the charging voltages of different times are displayed.

Formula for calculating the discharge voltage

\(\displaystyle U_C=U_0 · e^{-\frac{t}{τ}}\)

\(\displaystyle τ=R ·C\)


\(\displaystyle R\)

Resistor (Ω)

\(\displaystyle C\)

Capacitor (F)

\(\displaystyle τ\)

Time constant (sec)

\(\displaystyle U_0\)

Applied voltage (V)

\(\displaystyle U_C\)

Charging voltage at the capacitor (V)

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