ELECTRICAL / CALCULATOR
RL Time Constant
Calculate the current-response time constant from inductance and equivalent circuit resistance.
Input Parameters
Edit the example values. Results update as you type.
Results
- RL Time Constant
- 0.005s
Formula
τ = L / RSubstitution
τ = 0.1 H / 20 Ω = 0.005 sCalculation Steps
- Convert inductance to H and resistance to Ω.
- Divide inductance by equivalent resistance to obtain the ideal first-order time constant.
Result Explanation
Table percentages describe inductor current relative to its final value under a step input.
| Multiple | Time (s) | Rise Toward Final Value | Remaining After Decay |
|---|---|---|---|
| 1τ | 0.005 | 63.21% | 36.79% |
| 3τ | 0.015 | 95.02% | 4.98% |
| 5τ | 0.025 | 99.33% | 0.674% |
Formulas and FAQ
τ = L / RShould resistance include the coil or external resistor?
Enter the equivalent resistance seen by the inductor, including relevant coil, external and source resistance.