Use this circuit calculation for ideal components under the stated series, parallel, or first-order RC model with compatible SI units.

Resistance (ohm)

Required number in ohm. Resistance R in ohms.

Capacitance (F)

Required number in F. Capacitance C in farads.

The cited overview of Electrical network supplies background for the terminology and domain context used by this tool.^[1]

Compute the resistor-capacitor time constant tau = R*C. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Time constant (s)

Returned number in s. Tau = R*C in seconds; about 63.2% charge after one tau.

• Tolerance, temperature, frequency dependence, parasitics, leakage, source impedance, transients, and component ratings are outside an ideal lumped calculation unless explicitly supplied.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

Check component datasheets and tolerances, then validate consequential designs with circuit simulation and measurement under expected operating conditions.

• AC Power Triangle Calculator

  Derive apparent power, signed reactive power, and phase angle from nonnegative real power and a leading or lagging power factor.

• Electrical Current Calculator

  Calculate electrical current from voltage and resistance using Ohm's law.

• Parallel Resistance Calculator

  Combine resistors in parallel into one equivalent resistance via reciprocal summation.