Series/Parallel Capacitor Calculator

The Series/Parallel Capacitor Calculator finds the equivalent capacitance of any number of capacitors wired in series or in parallel. Enter your capacitors in any mix of pF, nF, µF, mF or F and the tool instantly returns the combined capacitance, draws an animated circuit diagram, and — the part most calculators skip — shows exactly how charge and voltage distribute across each individual capacitor. Add an applied voltage and it also reports the total stored charge and energy.

Series vs Parallel Capacitor Formulas

Capacitors combine using two simple rules. The trick to remember is that they behave the opposite way to resistors.

In parallel, connecting capacitors side by side is like enlarging the plate area, so the total capacitance grows. In series, stacking capacitors increases the effective distance between the outer plates, so the equivalent capacitance shrinks — it is always smaller than the smallest capacitor in the string.

Why Capacitors Are the Opposite of Resistors

This is the single most common point of confusion in circuit analysis. Resistors add in series and use the reciprocal rule in parallel. Capacitors are flipped: they add in parallel and use the reciprocal rule in series. The reason is physical — resistance opposes current and stacks up end to end, while capacitance stores charge on plates, and putting plates side by side (parallel) simply gives you more area to store charge.

How Charge and Voltage Distribute

Capacitors in Series

Every capacitor in a series string carries exactly the same charge (Q). Because Q = C × V, the voltage across each capacitor is inversely proportional to its capacitance: the smallest capacitor takes the largest share of the voltage. This is critical when you rate capacitors for voltage — a small capacitor in the string can be over-stressed even if the total voltage looks safe.

Capacitors in Parallel

Every capacitor in parallel sees the same voltage (the full supply voltage). The charge splits in direct proportion to capacitance: the largest capacitor stores the most charge. Adding capacitors in parallel is the standard way to build a larger bulk-capacitance reservoir in a power supply.

Stored Energy and Charge

When you enter an applied voltage, the calculator also reports the total charge and stored energy of the combination:

Capacitor Unit Reference

How to Use This Calculator

1. Choose the configuration: Pick Series or Parallel to match how the capacitors are wired in your circuit.
2. Enter your capacitors: Type each value and select its unit. Press "Add capacitor" for as many as you need (up to 12).
3. Add a voltage (optional): Enter the applied voltage to also get total charge, stored energy, and the voltage across each capacitor.
4. Click Calculate: Read off the equivalent capacitance, the animated diagram, and the per-capacitor distribution, plus a side-by-side series-vs-parallel comparison.

Worked Example

Three capacitors — 100 µF, 220 µF and 470 µF — in parallel give C_eq = 100 + 220 + 470 = 790 µF. The same three in series give 1/C_eq = 1/100 + 1/220 + 1/470 ≈ 0.01669, so C_eq ≈ 59.9 µF — smaller than the 100 µF capacitor, exactly as the series rule predicts.

Frequently Asked Questions

How do you calculate capacitors in parallel?

Capacitors in parallel simply add together: C_eq = C₁ + C₂ + … + Cₙ. Connecting capacitors in parallel increases the total capacitance because it effectively increases the combined plate area.

How do you calculate capacitors in series?

For capacitors in series you add the reciprocals: 1/C_eq = 1/C₁ + 1/C₂ + … + 1/Cₙ, then take the reciprocal of the result. The equivalent series capacitance is always smaller than the smallest capacitor in the string.

Why do capacitors combine the opposite way to resistors?

Resistors add in series and use the reciprocal rule in parallel. Capacitors are the reverse: they add in parallel and use the reciprocal rule in series. This is because capacitance is proportional to plate area, so parallel connection adds area, while series connection increases the effective plate separation and reduces capacitance.

How does voltage divide across capacitors in series?

Series capacitors all carry the same charge, so the voltage across each capacitor is inversely proportional to its capacitance: V_i = Q / C_i. The smallest capacitor takes the largest share of the voltage, which matters for voltage ratings.

How much energy does a capacitor bank store?

The energy stored in the equivalent capacitance is E = ½ × C_eq × V², where C_eq is the equivalent capacitance and V is the applied voltage. This calculator reports the total stored energy whenever you provide a voltage.

Do capacitors need to be the same value?

No. You can combine capacitors of any value in series or parallel. This calculator accepts mixed values and units, and shows how the charge or voltage distributes across each individual capacitor.

Additional Resources

• Capacitor - Wikipedia
• Series and Parallel Circuits - Wikipedia