RC Capacitor Charge Time

Calculate RC charging time to reach a target capacitor charge.

How this calculator works

Enter resistance (ω), capacitance (µf), target charge (%). CalcStack applies the displayed formula and reports each intermediate planning value with the units shown.

Formula / method

t = −RC ln(1 − target fraction)

Worked example

10 kΩ and 100 µF reach 99% charge in about 4.605 seconds.

Assumptions and limitations

Supply voltage is constant and the capacitor starts discharged.

Leakage, ESR, load current, tolerance and nonlinear circuits are excluded.