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Capacitor Charge Calculator

Calculate RC circuit time constant, capacitor charge/discharge times, and voltage at each time step.

Time Constant (τ = RC)

1000.000 ms

At 1τ: 63.2% charged — At 5τ: 99.3% charged

Charge curve (V = Vs × (1 − e^(−t/τ)))

TimeVoltage (V)% Charged
0 (0τ)0.0000
0.0%
1000.000 ms (1τ)3.1606
63.2%
2.000 s (2τ)4.3233
86.5%
3.000 s (3τ)4.7511
95.0%
4.000 s (4τ)4.9084
98.2%
5.000 s (5τ)4.9663
99.3%

How the RC time constant works

In an RC circuit, τ (tau) = R × C is the time constant. The capacitor charges to 63.2% of the supply voltage after 1τ, 86.5% after 2τ, and ~99.3% after 5τ (considered fully charged). The voltage formula is: V(t) = V_supply × (1 − e^(−t/τ)).

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