RC Circuit Calculator
Calculate time constant and voltages for an RC circuit.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
Can't find what you need?
Request a ToolHow to Use the RC Circuit Calculator
Enter the resistance, capacitance, supply voltage, and the time elapsed. The calculator shows the time constant and the charging/discharging voltages at that time.
About RC Circuit
An RC circuit consists of a resistor and capacitor connected in series. When voltage is applied, the capacitor charges exponentially with a time constant tau = RC. The charging voltage follows V(t) = Vs(1 - e^(-t/tau)) and the discharging voltage follows V(t) = V0 e^(-t/tau). RC circuits are fundamental building blocks in electronics, used in filters, oscillators, and timing circuits.
Frequently Asked Questions
What is the time constant?
The time constant (tau = RC) is the time for a charging capacitor to reach about 63.2% of the supply voltage, or for a discharging capacitor to drop to about 36.8% of its initial voltage.
How long to fully charge a capacitor?
A capacitor is considered fully charged after about 5 time constants (5 tau), reaching 99.3% of the supply voltage.
How is an RC circuit used?
RC circuits are used for filtering, timing, coupling, and decoupling in electronics. They form the basis of integrators, differentiators, and simple delay circuits.