Parallel Capacitor Calculator

Enter up to three capacitor values and a supply voltage to find the total (equivalent) capacitance of a parallel bank, plus the total charge and energy it stores.

Quick Facts

Parallel capacitance formula
C_total = C1 + C2 + C3 + …
Capacitances in parallel simply add — the opposite of how resistors combine in parallel.
Shared voltage
V1 = V2 = V3 = V_supply
Every capacitor in a parallel bank sees the full supply voltage.
Charge per capacitor
Qi = Ci × V
Charge divides between capacitors in proportion to their capacitance.
Stored energy
E = ½ × C_total × V²
Total energy stored across the whole parallel bank.

Your Results

Calculated
Total (Equivalent) Capacitance
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C_total = C1 + C2 + C3
Total Charge Stored
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Q = C_total × V
Total Energy Stored
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E = ½ × C_total × V²
Charge on Each Capacitor
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Qi = Ci × V

Ready

Enter your capacitor values, choose a unit, and press Calculate.

How to Use the Parallel Capacitor Calculator

When two or more capacitors are wired in parallel, their leads are tied together in matching pairs so every capacitor sits across the exact same two nodes — and therefore the exact same voltage. This calculator adds up to three capacitor values to find the total (equivalent) capacitance of the bank, then combines that total with your supply voltage to find the total charge and energy stored, and how that charge splits between the individual capacitors.

Why capacitance adds in a parallel connection

A capacitor's value depends on the geometry of its plates: C = ε × A / d, where A is plate area, d is the plate separation, and ε is the permittivity of the dielectric between them. Connecting capacitors in parallel is electrically equivalent to increasing the total plate area while the separation and dielectric stay the same, so the capacitances simply add: C_total = C1 + C2 + C3 + …. This is the opposite of resistors, which add directly in series and combine reciprocally (1/R_total = 1/R1 + 1/R2 + …) in parallel — capacitors do it the other way around.

Charge, voltage, and energy in a parallel bank

Because every capacitor in a parallel group shares the same two nodes, each one carries the full source voltage: V1 = V2 = V3 = V_supply. Each capacitor still stores its own charge according to Q = C × V, so a larger capacitor in the bank stores proportionally more charge at that same voltage. The total charge delivered by the source is Q_total = C_total × V, and the total energy stored across the whole bank is E = ½ × C_total × V² — the same energy formula used for a single capacitor, applied to the combined capacitance.

Practical notes for building a parallel bank

  • Match voltage ratings, not capacitance values — every capacitor in the bank must be rated for at least the full supply voltage, since they all see it simultaneously.
  • Adding a small capacitor in parallel with a much larger one barely changes the total capacitance, but a small ceramic capacitor alongside a large electrolytic still helps filter high-frequency noise that the larger capacitor responds to too slowly.
  • Combining electrolytic capacitors in parallel is common for smoothing power-supply ripple — the larger total capacitance lowers ripple voltage for a given load current.
  • Unlike a series combination, a parallel bank's total capacitance is always at least as large as its biggest individual capacitor.

Frequently Asked Questions

Why do capacitor values add in parallel instead of combining like resistors?
A capacitor's value depends on its plate area (C = εA/d). Wiring capacitors in parallel effectively increases the total plate area while the plate separation stays the same, so the capacitances add directly: C_total = C1 + C2 + C3 + ... This is the opposite of resistors, which add directly in series and combine reciprocally in parallel.
What voltage rating do capacitors need when wired in parallel?
Every capacitor in a parallel bank sees the same full supply voltage, so each one must be rated for at least that voltage. The bank's overall safe operating voltage is limited by whichever capacitor has the lowest voltage rating, even though the total capacitance is larger than any single capacitor.
How does charge divide between capacitors connected in parallel?
Charge divides in proportion to capacitance: Qi = Ci × V. Since every capacitor shares the same voltage V, a capacitor with twice the capacitance of another stores exactly twice the charge at that voltage.
How much energy is stored in a parallel capacitor bank?
Total stored energy is E = ½ × C_total × V², using the combined (summed) capacitance and the shared supply voltage — the same formula used for a single capacitor, just with the equivalent capacitance in place of one capacitor's value.

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