Input Parameters
About This Calculator
- τ = R × C where R in Ω, C in Farads
- 1τ = 63.2% charge, 3τ = 95%, 5τ = 99.3%
- Input μF, output in milliseconds
How this RC time constant calculator works
The time constant τ = R × C. With R in ohms and C in farads, τ is in seconds. Enter μF and we auto-convert.
At 1τ the capacitor reaches 63.2% of final voltage. At 5τ it reaches 99.3%, considered fully charged.
FAQ
What is RC time constant?
τ = R × C. Time for capacitor to charge to 63.2% through a resistor.
How to calculate τ?
Multiply resistance (Ω) by capacitance (F). 10kΩ × 100μF = 1s.
What is 5τ?
99.3% charged — considered fully charged in practice.