Capacitor Calculator
Free Capacitor Calculator for electricity. Enter variables to compute results with formulas and detailed steps. Get results you can export or share.
Reviewed by Manoj Kumar, Mathematics Educator
Formula
Series: 1/Ct = 1/C1 + 1/C2 + ... | Parallel: Ct = C1 + C2 + ...
For series connections, the reciprocal of total capacitance equals the sum of reciprocals of individual capacitances. For parallel connections, total capacitance is the sum of all individual capacitances. Energy stored: E = 0.5CV2. Charge: Q = CV.
Worked Examples
Example 1: Series Capacitor Combination
Problem:Three capacitors of 100 uF, 220 uF, and 470 uF are connected in series across a 12V supply. Find the total capacitance and stored energy.
Solution:1/Ctotal = 1/100 + 1/220 + 1/470\n1/Ctotal = 0.01 + 0.004545 + 0.002128\n1/Ctotal = 0.016673\nCtotal = 59.98 uF\n\nEnergy = 0.5 x 59.98e-6 x 12^2\nEnergy = 0.5 x 59.98e-6 x 144\nEnergy = 4.319 mJ
Result:Total Capacitance: 59.98 uF | Energy: 4.319 mJ | Charge: 719.7 uC
Example 2: Parallel Capacitor Combination
Problem:The same three capacitors (100 uF, 220 uF, 470 uF) are connected in parallel across 12V. Find total capacitance and stored energy.
Solution:Ctotal = 100 + 220 + 470 = 790 uF\n\nEnergy = 0.5 x 790e-6 x 12^2\nEnergy = 0.5 x 790e-6 x 144\nEnergy = 56.88 mJ\n\nCharge = 790e-6 x 12 = 9,480 uC
Result:Total Capacitance: 790 uF | Energy: 56.88 mJ | Charge: 9,480 uC
Frequently Asked Questions
What is a capacitor and how does it store energy?
A capacitor is a passive electronic component that stores electrical energy in an electric field between two conductive plates separated by a dielectric material. When voltage is applied across the plates, opposite charges accumulate on each plate, creating an electric field that stores energy. The amount of energy stored is given by the formula E = 0.5 times C times V squared, where C is the capacitance and V is the voltage. Capacitors can release their stored energy very quickly, which makes them useful for applications requiring rapid bursts of power such as camera flashes, defibrillators, and power supply filtering in electronic circuits.
What is the difference between series and parallel capacitor connections?
In a series connection, capacitors are connected end to end so the same charge flows through each one, and the total capacitance decreases according to the reciprocal formula: 1/Ctotal = 1/C1 + 1/C2 + 1/C3. In a parallel connection, capacitors share the same voltage across their terminals, and the total capacitance simply adds up: Ctotal = C1 + C2 + C3. This is the opposite behavior of resistors, where series resistances add and parallel resistances use the reciprocal formula. Series connections are used when higher voltage ratings are needed, while parallel connections increase the total storage capacity of the circuit.
How do you choose the right capacitor for a circuit?
Choosing the right capacitor involves considering several key parameters: capacitance value for the required energy storage or filtering, voltage rating that exceeds the maximum expected voltage by at least 20 percent for safety margin, temperature rating for the operating environment, and equivalent series resistance (ESR) for power applications. The dielectric type also matters significantly because it affects temperature stability, voltage coefficient, and frequency response. Ceramic capacitors work well for high-frequency decoupling, electrolytic capacitors suit bulk energy storage in power supplies, and film capacitors are preferred for audio and precision applications due to their low distortion and excellent stability.
What is the energy stored in a capacitor and how is it calculated?
The energy stored in a capacitor is calculated using the formula E = 0.5 times C times V squared, where C is the capacitance in farads and V is the voltage across the capacitor. This quadratic relationship with voltage means doubling the voltage quadruples the stored energy, while doubling the capacitance only doubles the stored energy. A typical 1000 uF capacitor charged to 50 volts stores 1.25 joules of energy. While this seems small compared to batteries, capacitors can deliver this energy in microseconds, producing enormous instantaneous power. Supercapacitors with capacitances of hundreds of farads can store enough energy to briefly power electronic devices.
References
Reviewed by Manoj Kumar, Mathematics Educator · Editorial policy