Capacitor Charge Time Calculator: RC Time Constant and Voltage

Your details

Total series resistance in the RC circuit.
Capacitance of the capacitor.
Voltage applied across the RC circuit.
V
Percentage of supply voltage to reach. Must be less than 100% (theoretical full charge takes infinite time).
%
Time constant (τ)Fast circuit (< 1 ms)
0.0001s

Time to charge to 63.2% of supply voltage

Time to reach target %0.0005s
Time to 99% charge0.0005s
Voltage at 1τ5.6891V
Voltage at target %8.91V
Energy stored (at full charge)4,050μJ
0.0001 s
Microsecond range<0.001Millisecond range0.001-1Second range1+

RC time constant is 100.0 μs; charging to 99% takes 460.5 μs.

  • The time constant τ = 100.0 μs means the capacitor reaches 63.2% of 9 V in that time.
  • To reach 99% of supply voltage takes 460.5 μs.
  • At 5τ (500.0 μs) the voltage is 99.3%, which engineers treat as fully charged.
  • The energy stored at full charge is 4.050 mJ (E = ½CV²).

Next stepTo reduce charge time, lower R, lower C, or both. To store more energy, increase C or increase the supply voltage (energy scales with V²).

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