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Electrical / Capacitors
RC Time Constant Calculator
Calculate τ and the ideal charging and remaining percentages through five time constants.
RC network
Time constant
One time constant1 s
63.2% charged · 36.8% remaining
- 1τ · 1 s
- 63.21% charged · 36.79% remaining
- 2τ · 2 s
- 86.47% charged · 13.53% remaining
- 3τ · 3 s
- 95.02% charged · 4.98% remaining
- 4τ · 4 s
- 98.17% charged · 1.83% remaining
- 5τ · 5 s
- 99.33% charged · 0.67% remaining
Percentages describe an ideal first-order step response. “Remaining” is the discharge voltage percentage or the charging error relative to the final voltage.