About this calculator
Connect capacitors together and their capacitances combine, but the rules are the opposite of resistors: in parallel they add up, in series you add the reciprocals.
Enter the values in microfarads (µF), separated by commas or spaces. Add a voltage if you also want the stored charge and energy.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
Two 10 µF capacitors in series at 12 V
- Total capacitance (series)
- 5 µF
- In microfarads
- 5 µF
- Charge at 12 V
- 60 µC
- Energy stored at 12 V
- 0.36 mJ
2 capacitors (10 µF, 10 µF) in series give 5 µF.
Show the working
- In series, add the reciprocals: 1 ÷ C = 1/10 + 1/10 = 0.2.
- So C = 1 ÷ 0.2 = 5 µF.
- The total is always smaller than the smallest single capacitor.
- At 12 V: charge Q = C × V = 5 µF × 12 V = 60 µC, and energy = ½ C V² = 0.36 mJ.
10, 22 and 4.7 µF in parallel
- Total capacitance (parallel)
- 36.7 µF
- In microfarads
- 36.7 µF
3 capacitors (10 µF, 22 µF, 4.7 µF) in parallel give 36.7 µF.
Show the working
- In parallel, capacitances simply add: 10 + 22 + 4.7 = 36.7 µF.
- The total is always bigger than the largest single capacitor.
Three 100 µF in series at 5 V
- Total capacitance (series)
- 33.333333 µF
- In microfarads
- 33.333333 µF
- Charge at 5 V
- 166.666667 µC
- Energy stored at 5 V
- 0.416667 mJ
3 capacitors (100 µF, 100 µF, 100 µF) in series give 33.333333 µF.
Show the working
- In series, add the reciprocals: 1 ÷ C = 1/100 + 1/100 + 1/100 = 0.03.
- So C = 1 ÷ 0.03 = 33.333333 µF.
- The total is always smaller than the smallest single capacitor.
- At 5 V: charge Q = C × V = 33.333333 µF × 5 V = 166.666667 µC, and energy = ½ C V² = 0.416667 mJ.
The formulas
- Parallel: C = C₁ + C₂ + C₃ + …
- Series: 1/C = 1/C₁ + 1/C₂ + 1/C₃ + …
- Charge: Q = C V
- Energy: E = ½ C V²
Why the rules flip
Parallel capacitors act like one bigger plate area, so capacitance adds. Series capacitors make the gap between plates effectively wider, which reduces capacitance. That is why the series total is always smaller than the smallest capacitor and the parallel total larger than the largest.
Voltage ratings
In series, the voltage splits between the capacitors, so the combination can tolerate more voltage than one alone (if the values match). In parallel every capacitor sees the full voltage, so the lowest voltage rating limits the group. Always leave a safety margin.
Frequently asked questions
Do capacitors add in series like resistors?
No. Resistors add in series; capacitors add in parallel. It is the other way round.
What unit should I enter?
Microfarads (µF). For nanofarads, divide by 1,000 (47 nF is 0.047 µF).
How much energy does a capacitor store?
Energy = ½ × C × V². Doubling the voltage quadruples the energy.
Can I mix different values?
Yes, any values can be combined.
Is the total in the same units?
The result is shown in the most readable unit (pF, nF, µF or mF), and also in microfarads.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.