Resistor capacitor circuit calculator

Calculate an RC time constant τ = RC and ideal capacitor charging and discharging voltages.

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Resistance (ohms)

Capacitance (µF)

More inputs and assumptions

Supply voltage (V)

Elapsed time (s)

Answer

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Calculate an RC time constant τ = RC and ideal capacitor charging and discharging voltages.

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Formula and assumptions

Charging assumes zero initial capacitor voltage; discharging starts at the entered supply voltage. Capacitance is entered in microfarads. Ideal components and a step input; no voltage or thermal rating assessment.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Resistor capacitor circuit calculator

Calculate an RC time constant τ = RC and ideal capacitor charging and discharging voltages.

Next: Series and parallel capacitor calculator

A worked example

Example inputs: resistance (ohms) = 1000, capacitance (µf) = 1000, supply voltage (v) = 10, elapsed time (s) = 1. Time constant (s) = 1.

Before you use the result

Example results for resistance (ohms)

These examples use Capacitance (µF): 1000; Supply voltage (V): 10; Elapsed time (s): 1. They are reference calculations, not recommended settings.

Resistance (ohms)	Time constant (s)
500	0.5
1000	1
2000	2

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