Capacitors in Series and Parallel Calculator

Combining capacitors is a daily task in electronics, and the rules are the neat opposite of the ones for resistors, so this calculator does both at once: enter a list of capacitor values and it gives you the total capacitance if they are wired in series and if they are wired in parallel, side by side, updating as you type. The two arrangements behave very differently. In parallel, capacitors simply add together, because connecting them side by side is like enlarging the plate area available to store charge, so the combined capacitance is the straightforward sum and is always bigger than any single one. In series, the capacitors are joined end to end, which effectively increases the distance between the outer plates, and capacitance falls as that separation grows, so you add the reciprocals and take the reciprocal of the total, exactly the method used for resistors in parallel, and the result is always smaller than the smallest capacitor in the chain. That mirror-image behaviour, parallel for resistors looking like series for capacitors and vice versa, is one of the tidy symmetries of circuit theory and a common source of confusion, which seeing both totals together helps clear up. Whatever unit you enter, microfarads, nanofarads or picofarads, the answers come back in the same unit, since the formulas are unit-independent as long as you stay consistent. That makes the tool genuinely useful for electronics students learning about capacitors and circuit combinations and checking homework, and for hobbyists and engineers building filters, timing circuits, power supplies and snubbers, where you often need to reach a particular capacitance by combining the values you have on hand. The formulas and a worked example are explained clearly below.

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In parallel60
In series5.45455

Results are in the same unit you entered (e.g. microfarads). Parallel adds; series uses reciprocals.

How it works

In parallel, the total capacitance is the sum of all the values. In series, the total is the reciprocal of the sum of the reciprocals, so one over the total equals one over the first plus one over the second, and so on. The series total is always less than the smallest capacitor; the parallel total is always more than the largest.

Worked example

For capacitors of 10, 20 and 30 microfarads: in parallel the total is 10 plus 20 plus 30, which is 60 microfarads. In series, one over the total is one tenth plus one twentieth plus one thirtieth, which gives about 5.45 microfarads.

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Frequently asked questions

How do you add capacitors in parallel?

Capacitors in parallel simply add up, so the total is the sum of the individual capacitances. Parallel connection effectively increases the plate area, so the combined capacitance is always larger than any single capacitor.

How do you add capacitors in series?

For capacitors in series, you add the reciprocals and take the reciprocal of the result, like resistors in parallel. The total is always smaller than the smallest capacitor in the chain, because the effective plate separation increases.

Why are capacitors opposite to resistors?

Capacitance depends on geometry in the opposite way to resistance, so the rules swap. Capacitors add in parallel and combine by reciprocals in series, which is the reverse of resistors, where you add in series and use reciprocals in parallel.