Series/Parallel Capacitor Calculator
Combine any number of capacitor values in series or parallel.
Capacitor values (µF)
Parallel connection — shared rails, capacitance adds directly.
Series connection — one chain, reciprocals add.
For reference and prototyping. Verify any safety- or design-critical value against the component datasheet or a second method before relying on it. Full disclaimer.
About this tool
Add or remove any number of capacitor values and get both totals at once: the parallel total (plain sum — the combination almost every circuit actually uses) and the series total (reciprocal sum) — the reverse of how resistors combine, because capacitance and resistance respond oppositely to changing a component's physical geometry.
The two formulas. In parallel, capacitance adds directly: Ctotal = C₁ + C₂ + … + Cₙ. In series, it's the reciprocals that add: 1/Ctotal = 1/C₁ + 1/C₂ + … + 1/Cₙ, so the total is always smaller than the smallest individual value — the mirror image of resistors, where parallel gives the smaller total. For just two capacitors in series there's a shortcut: Ctotal = (C₁×C₂) / (C₁+C₂).
Why the direction flips. A capacitor's value is proportional to plate area and inversely proportional to plate separation. Wiring capacitors in parallel is electrically equivalent to one capacitor with a larger combined plate area, so the values add. Wiring them in series is equivalent to one capacitor with a greater effective separation between its outermost plates, so it's the reciprocals — proportional to separation — that add. Resistors work the other way because resistance is proportional to length (which adds in series) and inversely proportional to cross-sectional area (which effectively adds in parallel).
Worked example. With the default values 10, 22, and 47 µF: the parallel total is the plain sum, 10 + 22 + 47 = 79 µF. The series total is the reciprocal sum inverted: 1/10 + 1/22 + 1/47 = 0.16667 + 0.04545 + 0.02128 ≈ 0.16673, and 1 ÷ 0.16673 ≈ 5.998 µF — smaller than even the 10 µF capacitor alone.
| Formula | Result vs. individual values | |
|---|---|---|
| Parallel | C₁ + C₂ + … | Always larger than the largest value |
| Series | 1 ÷ (1/C₁ + 1/C₂ + …) | Always smaller than the smallest value |
Why you'd actually wire capacitors this way. Parallel combinations are by far the more common: stacking several capacitors on a power rail (decoupling/bypass capacitors) increases total bypass capacitance and lets each individual part have a smaller ESR and better high-frequency response than one big capacitor would. Series combinations show up when a single capacitor's voltage rating isn't high enough — putting two 400 V capacitors in series can withstand up to 800 V across the pair, at the cost of a lower total capacitance and (in real circuits) added balancing resistors, since leakage differences between real capacitors mean the voltage doesn't split exactly evenly.
Real capacitors vs. this calculator. These formulas assume ideal capacitors. Real parts add tolerance (often ±10-20%), equivalent series resistance (ESR), and leakage current, all of which this tool ignores — it computes the textbook combination, which is the right starting point for a design before checking real part specs.
For the opposite combination rule, see the resistor color code tool (series adds directly for resistors). To decode a capacitor's printed marking into a value first, use the capacitor code decoder. To use a capacitor value in a timing circuit, see the RC time constant calculator, and for the rest of Ohm's law, the Ohm's law calculator.
Everything runs locally in your browser — no values are sent anywhere.
Frequently asked questions
- Why is parallel the sum for capacitors but series was the sum for resistors?
- Capacitance and resistance combine oppositely: putting capacitors in parallel adds their plate areas (so capacitance adds directly), while putting them in series effectively increases plate separation (so it's the reciprocals that add) — the reverse of how resistors behave.
- What's the shortcut for just two capacitors in series?
- Ctotal = (C₁×C₂) ÷ (C₁+C₂) — the "product over sum" rule, equivalent to the full reciprocal formula but quicker for two values.
- Can I mix units like nF or pF directly?
- Enter everything in the same unit (typically µF) — this tool treats every number as a plain value in µF, so convert nF/pF values first (e.g. 100nF → 0.1).
- What happens with a 0µF value?
- It's included as-is in the parallel sum (adding nothing) but is skipped in the series calculation, since a 0µF capacitor in series would block the whole branch entirely — the hint will flag this.
- Does putting capacitors in series really increase the voltage they can handle?
- Roughly, yes — the applied voltage splits across the capacitors in series, so their combined rating is higher than any one alone. In practice it doesn't split perfectly evenly because real capacitors have slightly different leakage, so designs often add balancing resistors across each capacitor to force a more even split.
- Is there a limit to how many capacitors I can add?
- No hard limit — use "+ Add capacitor" as many times as needed. The diagrams stay readable for a handful of capacitors; with a large number they'll simply draw more tightly packed.
- Are these results exact for real-world capacitors?
- They're the ideal textbook combination. Real capacitors carry tolerance, ESR, and leakage that this calculator doesn't model, so treat the result as the target value before checking actual part specs.