Capacitor Charge Time Calculator

Calculate the time it takes to charge a capacitor to the level of the input voltage.


Vc = Vi (1-e-t/τ)


  • Vi = Input Voltage
  • τ = time constant
  • Vc = voltage at the capacitor at time t

time constant τ = RC, where R is resistance and C is capacitance.

At t = 5*RC = (or 5 time constants),

Vc/Vi = (1-e-5) = 0.9933

In other words, at t = 5τ, the capacitor voltage reaches 99.33% of the input voltage.

Example Calculation

For R = 1 kΩ and C = 1 nF, the capacitor charging time is 5 µs.

Related Calculators

Capacitor Discharge Time – How long does it take for a cap to discharge to a final voltage level?