Capacitor Calculator
This capacitor calculator combines up to three capacitances in series or parallel, works out the energy stored at a given voltage and, with a resistor, the RC time constant.
Example: Circuit: Parallel · Capacitance C1 10 µF · Capacitance C2 22 µF · Resistor for the RC circuit (optional) 10,000 Ω · Voltage (optional) 12 V → Total capacitance: Total capacitance 32 µF (parallel). Source: Wikipedia – Kondensator (Elektrotechnik): Parallel-/Reihenschaltung, Energie. Updated: .
How it is calculated
Two capacitors of 10 µF and 22 µF give 32 µF in parallel and about 6.9 µF in series. In parallel the capacitances add; in series the total falls below the smallest single value.
How it is calculated
For a parallel circuit C = C1 + C2 + C3. In series the reciprocals add: 1/C = 1/C1 + 1/C2 + 1/C3. The stored energy is E = ½ · C · V². With a resistor you form an RC circuit: the time constant is τ = R · C, and after 5 τ the capacitor is more than 99 % charged. The cut-off frequency of a simple RC filter is f = 1 / (2π · R · C).
Practical notes
- Electrolytics in series do not share voltage evenly; balancing resistors help.
- Parallel connection raises capacitance at the same voltage rating.
- Conversion: 1 µF = 1000 nF = 1,000,000 pF.
Frequently asked questions
How do you calculate total capacitance in parallel?
By adding: C = C1 + C2 + C3. The voltage rating stays that of the weakest capacitor.
How do you calculate total capacitance in series?
With 1/C = 1/C1 + 1/C2 + 1/C3. Two equal capacitors in series halve the capacitance.
What is the RC time constant?
τ = R · C. After this time a charging capacitor has reached about 63 % of the voltage, after 5 τ over 99 %.
How much energy does a capacitor store?
E = ½ · C · V². 100 µF at 12 V stores 7.2 mJ.
Sources and legal basis
- Wikipedia – Kondensator (Elektrotechnik): Parallel-/Reihenschaltung, Energie
- Wikipedia – Capacitor: Networks of capacitors, energy storage
- Wikipedia – RC circuit: time constant τ = RC, cutoff frequency
As of: · Editorial policy
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