Capacitor Charge and Time Constant Calculator

Online calculator for calculating the Time Constant and the Charging Voltage

Charging Voltage calculator

On this page you can calculate the charging voltage of a capacitor in an R/C circuit (low pass) at a specific point in time.

In addition to the values of the resistor and the capacitor, the applied input voltage and the time are given for the calculation.

The result shows the charging voltage at the specified time and the time constant τ (tau) of the RC circuit. The condenser is after a time of 5 τ approx. 99.33% charged. This means that at specified times that are significantly over 5 τ the input voltage is always close to the charging voltage.

Calculate charging voltage

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

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

Formula for calculating the charging voltage

\(\displaystyle U_C=U_0 ·\left(1-e^{-\frac{t}{τ}}\right)\)

\(\displaystyle τ=R ·C\)


\(\displaystyle R\)

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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