How this calculation works
Apply one ideal connection rule to the whole supplied list, then show each capacitor’s voltage, charge and energy. Keep equal series charge distinct from the sum of parallel branch charges.
Parallel: Ceq = ΣC; series: 1/Ceq = Σ(1/C); Q = CeqV; U = ½CeqV²A worked example
10, 20 and 30 µF in parallel give 60 µF. At 12 V, terminal charge is 720 µC and stored energy is 0.00432 J. In series, equivalent capacitance is about 5.454545 µF under the stated initial/node assumptions.
Good to know
Ideal all-series or all-parallel networks only. No general topology, initial charge imbalance, leakage, ESR, tolerance, transient or voltage-rating selection. Signed references do not establish component polarity suitability.
Reference: Reference: model definitions and scope (opens in a new tab) ↗
Capacitors and resistors do not use the same connection rule
The default 10, 20 and 30 µF capacitors add to 60 µF in parallel. In series, their reciprocal sum gives about 5.454545 µF, smaller than any individual capacitance. Reusing the resistor series rule for capacitors would reverse the result.
At the entered 12 V, the parallel network’s terminal charge is 720 µC and stored energy is 0.00432 J. Each parallel capacitor has 12 V across it; its charge depends on its capacitance. The branch charge sum equals the terminal charge in that topology.
The RC time constant calculator adds a resistor/source trajectory; equivalent capacitance alone does not specify the transient or a component voltage rating.
Equal series charge does not mean equal series voltage
For the same three capacitors in series at 12 V, the common charge is about 65.454545 µC. The 10 µF capacitor has about 6.545455 V, the 20 µF about 3.272727 V and the 30 µF about 2.181818 V. Those voltages add to the terminal voltage under the stated ideal node and initial-charge assumptions.
The common charge is not added three times to obtain charge delivered at the terminal. A series chain redistributes charge on its internal plates. Initial charge imbalances, leakage and a real charging path can change the problem; the tool does not reconstruct those missing conditions or assign safe voltage ratings.
A static equivalent is different from a charging trajectory
Reversing the terminal reference changes the signs of charge and voltage but not the positive stored energy, because energy uses voltage squared. Zero voltage gives zero modeled charge and stored energy for this initially uncharged ideal network.
The RC time constant calculator adds a separate resistor/source transient with an explicit initial capacitor voltage. The series RLC damping calculator describes another model that adds inductance and resistance. Equivalent capacitance alone does not determine how quickly a real network charges or how its components should be rated.
A few questions, answered
Do all series capacitors have the same voltage?
Not generally. Under this ideal series model they have equal charge, so voltage is charge divided by each capacitance.
Can I enter an arbitrary mixed network?
No. The supplied list is entirely series or entirely parallel.
Can stored energy be negative when voltage is negative?
No. The ideal expression ½CV² is non-negative. The voltage sign only changes the reference direction of charge.
Does the result allocate safe component voltage ratings?
No. Initial charge, tolerances, leakage, transient behavior and ratings require additional information.