RC Time Constant
The RC time constant sets the speed of a first-order charging or discharging response.
RC Time Constant
Timing · 2 inputs
How to use this calculator
- Enter resistance in kΩ.
- Enter capacitance in µF.
- Select Calculate and keep the output unit with the answer.
Before you use the answer
Check the component connections and unit prefixes before copying a result into a circuit notebook. These tools describe ideal, introductory circuits. They do not replace datasheets, thermal checks, isolation requirements or qualified design work, and they are not intended for mains installation decisions.
One time constant is not full charge; a charging capacitor reaches about sixty-three percent of its final voltage.
Does it save my inputs?
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Why might a result be approximate?
Measurement uncertainty, ideal-model assumptions and floating-point rounding can all matter. Displaying more digits does not improve the original measurement.
Related calculations
RC Charging Voltage
A capacitor initially at zero volts approaches a fixed supply exponentially through a resistor.
Open calculator ↗RC Discharging Voltage
An initially charged capacitor loses voltage exponentially through an ideal resistance.
Open calculator ↗RC Low-Pass Cutoff
A first-order RC low-pass cutoff is the frequency where amplitude falls to one over the square root of two.
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