Capacitor Calculator solves series and parallel capacitor networks, charge and stored energy, plus RC charging and discharging time. Choose a mode, enter practical units, and get a clear result breakdown with downloadable records.
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Capacitor Calculator formulas
For capacitors in parallel, capacitances add directly because every component shares the same voltage. For capacitors in series, the reciprocal values add and the equivalent capacitance is smaller than the smallest component.
Series: 1/Ceq = 1/C₁ + 1/C₂ + … + 1/Cₙ
Charge: Q = C × V
Stored energy: E = ½CV²
RC time constant: τ = R × C
The RC time constant describes exponential charging and discharging. After one time constant, an initially empty capacitor reaches about 63.2% of the supply voltage. After five time constants, it is normally treated as nearly fully charged.
Capacitor Calculator examples
Series and parallel example
Capacitors of 10 µF, 22 µF and 47 µF equal 79 µF in parallel. Connected in series, the same components equal approximately 6.00 µF. These limits provide a quick accuracy check for the Capacitor Calculator.
Charge and energy example
A 100 µF capacitor at 12 V stores 1.2 mC of charge and 7.2 mJ of energy. Energy rises with the square of voltage, so voltage rating and safe handling deserve careful attention.
RC timing example
A 10 kΩ resistor and 100 µF capacitor have a one-second time constant. The ideal charging curve reaches 63.2% in about one second, 86.5% in two seconds and 99.3% in five seconds.
Selecting capacitance and voltage ratings
Capacitance alone does not determine suitability. Check rated voltage, tolerance, dielectric type, equivalent series resistance, ripple-current rating, temperature range, polarity and expected service life. Choose a voltage rating above the highest possible circuit voltage and include margin for transients.
Real components differ from ideal formulas. Leakage current, lead resistance, parasitic inductance and dielectric absorption affect measurements. Electrolytic capacitors are commonly polarized, while ceramic and film types are generally non-polarized. Always confirm the datasheet before installation.
The Capacitor Calculator is intended for planning and education. It does not replace circuit simulation, measurement or qualified engineering review. For authoritative SI electrical units and measurement terminology, consult the NIST SI electrical-units guidance.
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Capacitor Calculator frequently asked questions
Does capacitor order matter in series or parallel?
No. Ideal equivalent capacitance is unchanged when the component order changes.
Why is series capacitance smaller?
Each series capacitor stores the same charge while the total voltage divides, producing an equivalent value below the smallest component.
What does five time constants mean?
After 5τ, ideal charging reaches about 99.3%, while ideal discharge leaves about 0.67%.
Can I mix capacitance units?
Convert all network values to the shared unit selected in the calculator. Other modes provide independent unit selectors.
Does the calculator include capacitor tolerance?
No. Results use nominal values. For critical designs, calculate worst-case limits from each component tolerance.