Capacitors in Series and Parallel Calculator
Find the equivalent capacitance of up to four capacitors in series or parallel, plus the total charge and energy at a supply voltage and the voltage, charge and energy of each capacitor.
How it works
Series: 1/C = 1/C₁ + 1/C₂ + … (same charge Q on each, Vᵢ = Q/Cᵢ) · Parallel: C = C₁ + C₂ + … (same voltage, charges add) · Q = C·V · E = ½·C·V²
Capacitors in parallel present more plate area to the same voltage, so their capacitances simply add. In series the same charge flows onto every capacitor and the voltages add, so the reciprocals add and the result is smaller than the smallest capacitor — the opposite of resistors. In a series string the smallest capacitor takes the largest share of the voltage, which matters for voltage ratings. These are the standard results in OpenStax University Physics Vol. 2, section 8.3.
Worked example
Capacitors of 10 µF, 22 µF and 47 µF in series: 1/C = 1/10 + 1/22 + 1/47 = 0.16673, so C = 5.998 µF. On 12 V the string stores Q = 5.998 × 12 = 71.97 µC and E = ½ × 5.998 µF × 12² = 431.8 µJ. The same 71.97 µC sits on each capacitor, so the voltages are 7.197 V, 3.271 V and 1.531 V.
Sources: OpenStax University Physics Vol. 2 — Capacitors in Series and in Parallel · HyperPhysics — Capacitor combinations
Frequently asked questions
Do capacitors in series add up?
No — their reciprocals add, so the total is always smaller than the smallest capacitor. Two equal capacitors in series give half the capacitance of one.
Why connect capacitors in series?
To raise the voltage rating: the voltage divides between them. Because the split depends on capacitance and leakage, real designs add balancing resistors across each capacitor.
Why connect capacitors in parallel?
To increase total capacitance and charge storage, or to lower the combined ESR and ripple current per capacitor in power supplies.
Is the rule for capacitors the opposite of resistors?
Yes. Resistors add in series and use reciprocals in parallel; capacitors add in parallel and use reciprocals in series. Springs behave like capacitors.
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This calculator is for educational purposes. Double-check important results before acting on them.