About the Capacitor Calculator
Capacitors can be connected side by side, called parallel, or one after another, called series, and the combined capacitance is different in each case. This calculator takes a list of capacitor values and the way they are connected, and gives the total. If you enter a voltage, it also works out the charge stored and the energy. Type the capacitor values, their unit and the connection and the combined capacitance appears at once, with a few related figures underneath, and you can copy the result with one tap. The sums run in your browser, so nothing you enter is uploaded.
Updated October 2026
How to use the Capacitor Calculator
- 1Enter the capacitor values, their unit and the connection.
- 2Pick the units or options from the menus if the combined capacitance tool offers them.
- 3Read the combined capacitance in the large result box.
- 4Look at the extra rows for related figures.
- 5Press Copy result to keep the answer.
When you need the combined capacitance
Electronics students and hobbyists combine capacitors to reach a value they do not have, or to raise the voltage rating by stacking in series. Designers add up decoupling capacitors in parallel to get low impedance across a wide range of frequencies.
The stored energy matters for safety and for flash units, defibrillators and power supplies. A larger capacitor at a higher voltage stores much more energy, because the energy grows with the square of the voltage.
How the combined capacitance is worked out
In parallel the capacitances add: C = C1 + C2 + … In series the reciprocals add: 1 ÷ C = 1 ÷ C1 + 1 ÷ C2 + … Charge = C × V and energy = ½ × C × V². Capacitors of 10, 22 and 47 µF in parallel give 79 µF; at 12 V they hold 948 µC and 5.69 mJ. The same three in series give only 5.998 µF, smaller than the smallest one.
Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.
- Any number of capacitors
- Series or parallel
- Optional voltage for charge and energy
Mistakes to avoid with combined capacitance
The series formula is the reverse of the one for resistors, which causes many slips. Remember that a series set is always below its smallest member. Also check the voltage rating: in series, the voltage divides unevenly unless the capacitors are matched.
On phone and computer
On a phone, type into the boxes one after another and read the combined capacitance underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the combined capacitance move. The capacitor calculator works the same on both. Capacitors come with other parts. Pick a resistor with Resistor Calculator, find the charging time with RC Time Constant Calculator, check currents with Ohm's Law Calculator, and see how a charge lasts with Battery Charge Time Calculator.
Features
- Parallel adds, series reduces
- Check voltage ratings
- Energy grows with voltage squared
- Clear messages when the combined capacitance inputs make no sense
- Copy the result with one tap
- Private: nothing is uploaded
Frequently asked questions
How do I calculate combined capacitance?
In parallel the capacitances add: C = C1 + C2 + … In series the reciprocals add: 1 ÷ C = 1 ÷ C1 + 1 ÷ C2 + … Charge = C × V and energy = ½ × C × V². Capacitors of 10, 22 and 47 µF in parallel give 79 µF; at 12 V they hold 948 µC and 5.69 mJ. The same three in series give only 5.998 µF, smaller than the smallest one.
What is the formula for combined capacitance?
In parallel the capacitances add: C = C1 + C2 + … In series the reciprocals add: 1 ÷ C = 1 ÷ C1 + 1 ÷ C2 + … Charge = C × V and energy = ½ × C × V². The capacitor calculator applies it exactly and rounds only the displayed answer to six significant figures.
Why is series capacitance smaller?
Because the plates are effectively moved further apart, like making one capacitor with a thicker gap.
Can I mix units?
Enter all values in one unit. Convert first if you have both µF and nF.
What does the energy figure tell me?
The energy stored at the voltage you give. It is released quickly when the capacitor discharges, so large values need respect.
Is this capacitor calculator free and private?
Yes. It is free, needs no account and runs in your browser, so the numbers you type are not uploaded or stored.