RL Time Constant Calculator

Enter resistance and inductance to calculate tau, 50/90/99 percent timing, and an ideal RL corner frequency.

Resistance

Inductance

—Time constant τ = L/R

—50% time

—90% time

—99% time

—R/(2πL)

Educational / low-voltage electronics calculator. Real components have tolerances and non-ideal behavior. Do not use this page as a substitute for qualified design or safety guidance for mains/high-energy electrical systems.

How to use this RL Time Constant Calculator

Calculate an ideal RL time constant and common current-rise timing points. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.