RC time constant: 1kΩ × 100µF = 100.00 ms (fc ≈ 1.6 Hz)
Worked answer for a first-order RC network of 1kΩ and 100µF: time constant, cutoff frequency and settling time.
Time constant τ 100.00 ms fc ≈ 1.6 Hz · settles in 500.00 ms (5τ)
| Resistor (R) | 1kΩ |
| Capacitor (C) | 100µF |
| Time constant τ = R · C | 100.00 ms |
| Cutoff frequency fc = 1 / (2π·R·C) | 1.6 Hz |
| Settling time (5τ, ≈99.3%) | 500.00 ms |
| Elapsed time | Multiple of τ | Charge |
|---|---|---|
| 100.00 ms | 1τ | 63.2% |
| 200.00 ms | 2τ | 86.5% |
| 300.00 ms | 3τ | 95% |
| 400.00 ms | 4τ | 98.2% |
| 500.00 ms | 5τ | 99.3% |
A charging capacitor reaches 63.2% of the final voltage after one time constant (100.00 ms) and is considered fully charged (≈99.3%) after five — here 500.00 ms.
Different values? Enter any R and C in the interactive tool:
Open the RC Time Constant Calculator →Disclaimer: These figures assume an ideal first-order RC network. Real resistors and capacitors carry tolerances, and capacitors have ESR and voltage/temperature dependence, so the measured time constant will differ. Confirm against your parts' datasheets.