RC Time Constant Table: Time constant (τ) by Resistance
Reference table of time constant (τ) for RC Time Constant across a range of resistance values — exact, engine-computed figures you can read off at a glance.
RC Time Constant Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Time constant (τ)
1.0000
- Time to ~full charge (5τ)
- 5.0000
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the RC Time Constant Calculator
The RC Time Constant Calculator works out your time constant (τ), along with 1 related figure in an instant. Enter resistance and capacitance and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Enter the resistance.
- Enter the capacitance.
- Read off your time constant (τ), together with time to ~full charge (5τ) — the calculator updates automatically, with no button to press.
Formula
The RC Time Constant Calculator uses the formula:
Time constant (τ) = Resistance × (Capacitance ÷ 1000000)
Worked example
For example, with resistance of 1,000 Ω and capacitance of 1,000 µF, the time constant (τ) is 1.0000.
| Resistance | 1,000 Ω |
|---|---|
| Capacitance | 1,000 µF |
| Time constant (τ) | 1.0000 |
|---|---|
| Time to ~full charge (5τ) | 5.0000 |
Results are estimates for educational use, not professional advice.
Frequently asked questions
Multiply resistance by capacitance: τ = R × C. A 1000 Ω resistor with a 1000 µF capacitor gives τ = 1 second.
In one time constant, a capacitor charges to about 63% of the supply voltage, or discharges to about 37%.
After about 5 time constants the capacitor is over 99% charged, which is usually treated as full.
It sets timing in filters, timers, debouncing circuits and many analogue designs where charge and discharge speed matters.
Enter the resistance. Enter the capacitance. Read off your time constant (τ), together with time to ~full charge (5τ) — the calculator updates automatically, with no button to press.
Related guides
How to Calculate RC Time Constant: Formula, Steps & Examples
Learn how to calculate RC Time Constant — the formula explained step by step, with worked examples and a free calculator to check your answer.