Time Constant Calculator (RC / RL)
Time Constant Calculator for RC and RL Circuits
Use this free online Time Constant Calculator to compute the time constant (τ) of RC (Resistor-Capacitor) and RL (Resistor-Inductor) circuits. It supports bidirectional calculations—allowing you to calculate τ, resistance (R), capacitance (C), or inductance (L) based on any known values.
This calculator is especially useful for electrical and electronics engineers, students, and circuit designers to understand the charging and discharging behavior of capacitors and inductors over time.
🔍 What is a Time Constant (τ)?
The time constant is a key parameter in transient analysis of first-order circuits:
- For RC circuits: τ = R × C
- For RL circuits: τ = L / R
It represents the time taken for the voltage or current to rise or fall to about 63.2% of its final value.
💡 Features of this Calculator
- Supports both RC and RL circuit types
- Bi-directional: calculate τ, R, C, or L
- Unit selector (Ω, kΩ, F, µF, H, mH, etc.)
- Auto-calculated values at 1τ to 5τ
- Real-time graph visualization for charging and current rise curves
- Fully mobile-friendly and easy to use
📈 Why Use This Calculator?
- Quickly simulate how capacitors charge or inductors build current
- Design timing elements in analog and digital circuits
- Learn and visualize first-order system responses
- Ideal for low-pass filters, differentiators, integrators, and switching circuits