Capacitor Calculator: Series and Parallel Capacitance
Pick series or parallel, enter up to six capacitor values in one unit (leave unused ones at 0) and the voltage across them. You get the total capacitance, the charge Q = C V and the stored energy E = 1/2 C V².
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Formula
- Parallel:
C_total = C1 + C2 + C3 + ... - Series:
1 / C_total = 1 / C1 + 1 / C2 + 1 / C3 + ... - Charge:
Q = C × V - Stored energy:
E = 1/2 × C × V²
A capacitor left at 0 is treated as not in the circuit. Capacitance is converted to farads inside the calculator and the total is shown back in the unit you chose; charge is shown in microcoulombs and energy in millijoules.
Worked example
Two capacitors, 10 µF and 22 µF, in series across 12 V:
1 / C = 1/10 + 1/22 = 0.145454..., soC = 6.875 µF.Q = 6.875 µF × 12 V = 82.5 µC.E = 0.5 × 6.875e-6 × 12² = 4.95e-4 J = 0.495 mJ.
The same two capacitors plus a 4.7 µF in parallel across 5 V give 36.7 µF, 183.5 µC and 0.45875 mJ.
Frequently asked questions
How do you add capacitors in parallel?
Capacitors in parallel simply add: C = C1 + C2 + C3 and so on. For 10 µF, 22 µF and 4.7 µF the total is 36.7 µF. Parallel connection gives a bigger plate area, so more capacitance.
How do you add capacitors in series?
In series the reciprocals add: 1/C = 1/C1 + 1/C2 + ... For 10 µF and 22 µF, 1/C = 0.1 + 0.04545 = 0.14545, so C = 6.875 µF. The total is always smaller than the smallest capacitor.
How much energy does a capacitor store?
Energy is E = 1/2 × C × V². A 6.875 µF combination charged to 12 V stores 0.5 × 6.875e-6 × 144 = 4.95e-4 J, which is 0.495 mJ. Doubling the voltage quadruples the energy.
How is the charge worked out?
Charge is Q = C × V. The same 6.875 µF at 12 V holds 82.5 µC. In a real series string of unequal capacitors every one carries this same charge, so the voltage divides unevenly: the smaller capacitor takes more of it.
Can I rely on this for a safety or voltage-rating decision?
No. This calculator is for learning and design checks, not safety certification. It assumes ideal capacitors with no leakage, tolerance, ESR or voltage derating, so always check each part's voltage rating and the datasheet, and discharge large capacitors safely.