RC Time Constant Calculator Formula
Understand the math behind the rc time constant calculator. Each variable explained with a worked example.
Formulas Used
Time Constant (τ)
tau = resistance * capacitance * 1e-6Time Constant (ms)
tau_ms = resistance * capacitance * 1e-6 * 1000Full Charge Time (5τ)
time_5tau = 5 * resistance * capacitance * 1e-6Variables
| Variable | Description | Default |
|---|---|---|
resistance | Resistance(Ω) | 10000 |
capacitance | Capacitance(μF) | 100 |
How It Works
RC Time Constant
The time constant characterizes how quickly a capacitor charges or discharges through a resistor.
Formula
τ = R * C
After one time constant, the capacitor reaches about 63.2% of its final value. After 5τ, it is over 99% charged.
Worked Example
A 10 kΩ resistor with a 100 μF capacitor.
resistance = 10000capacitance = 100
- 01τ = R * C
- 02τ = 10000 * 100e-6
- 03τ = 1.0 s
- 045τ = 5.0 s (99.3% charged)
Ready to run the numbers?
Open RC Time Constant Calculator