Capacitors in parallel formula
Capacitors connected across the same two nodes have the same voltage across each capacitor. Their capacitances add directly.
For example, 10 µF, 20 µF and 30 µF in parallel give a total capacitance of 60 µF.
Capacitors in series formula
For capacitors connected in series, add the reciprocals of the capacitances and then take the reciprocal of that sum.
The equivalent capacitance of positive capacitors in series is always smaller than the smallest individual capacitor.
Two capacitors in series
For exactly two capacitors, the series formula can also be written as:
Two 10 µF capacitors in series therefore have an equivalent capacitance of 5 µF.
Equal capacitors
If every capacitor has the same capacitance C, n identical capacitors in parallel have:
The same identical capacitors in series have:
Capacitor charge
If an applied voltage is entered, the calculator also finds the charge stored by the equivalent capacitance.
Charge is measured in coulombs. Because practical capacitance values are often small, the result may also be displayed in millcoulombs, microcoulombs or nanocoulombs.
Energy stored in a capacitor
The ideal energy stored by a capacitor is:
The calculator applies the equivalent capacitance to find the total ideal stored energy for the selected capacitor network.
Voltage across capacitors in parallel
Capacitors connected in parallel share the same two electrical nodes. Each capacitor therefore has the full applied voltage across it in the ideal model.
Voltage across capacitors in series
Ideal capacitors in series carry the same magnitude of charge. The voltage across each capacitor is therefore:
A smaller capacitance receives a larger share of the total series voltage when the ideal series capacitors carry equal charge.
pF, nF, µF, mF and F
Capacitor values are commonly expressed with several metric prefixes.
1 F equals 1,000 mF, 1,000,000 µF, 1,000,000,000 nF and 1,000,000,000,000 pF.
The calculator lets you choose a default unit and also accepts explicit entries such as 100nF, 4.7uF and 1mF.
Real capacitor limitations
Equivalent-capacitance formulas treat capacitors as ideal components. Real capacitors also have voltage ratings, tolerance, equivalent series resistance, leakage, temperature characteristics and frequency-dependent behavior.
In practical series capacitor banks, voltage sharing may also require balancing components. Do not assume ideal voltage division is sufficient for component-rating decisions.
Related electrical calculations
For resistor networks, use the Series & Parallel Resistor Calculator.
For voltage, current and resistance relationships, use the Ohm's Law Calculator.
For voltage-divider circuits, use the Voltage Divider Calculator.
This calculator uses ideal capacitor relationships. It does not evaluate capacitor voltage ratings, ESR, leakage, dielectric losses, ripple-current capability, transient behavior or balancing requirements.
Frequently asked questions
Do capacitors add in parallel?
Yes. Parallel capacitances add directly.
Why does capacitance decrease in series?
Series capacitors combine through the reciprocal-sum relationship, producing a total smaller than the smallest individual value.
Do series capacitors have the same voltage?
Not necessarily. Ideal series capacitors carry the same charge, so voltage is inversely related to capacitance.
Do parallel capacitors have the same voltage?
Yes. Ideal capacitors in parallel are connected across the same two nodes and therefore share the same voltage.
Can I mix nF and µF values?
Yes. Add the unit directly to an individual entry, such as 100nF or 4.7uF, while other values can use the selected default unit.
Using this calculator effectively
The Series & Parallel Capacitor Calculator finds equivalent capacitance for two or more capacitors. It supports pF, nF, µF, mF and F values and can also estimate charge, stored energy and ideal voltage distribution when an applied voltage is provided.
Common uses
- Combining capacitor values to find total capacitance in series or parallel.
- Checking ideal charge and stored energy for a capacitor network at a known voltage.
- Comparing ideal voltage distribution across capacitors connected in series.
Tips for a better estimate
- Use the unit printed on each capacitor or add an explicit suffix such as nF, uF or mF when mixing units.
- Treat series voltage distribution as an ideal calculation because real capacitor leakage and tolerance can affect voltage sharing.
- Check actual capacitor voltage ratings, ESR, ripple-current capability and manufacturer specifications before selecting components.
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