Enter capacitor values to calculate total capacitance
Note: The circuit diagram updates automatically as you add or remove capacitors.
Note: The circuit diagram updates automatically as you add or remove capacitors.
For 3-digit codes:
For 1-2 digit codes:
Series Connection:
1/Ctotal = 1/C1 + 1/C2 + ... + 1/Cn
For two capacitors: Ctotal = (C1 × C2) / (C1 + C2)
Parallel Connection:
Ctotal = C1 + C2 + ... + Cn
| Type | Typical Range | Applications |
|---|---|---|
| Ceramic | 1 pF - 1 μF | Decoupling, filtering |
| Electrolytic | 1 μF - 10,000 μF | Power supply filtering |
| Tantalum | 0.1 μF - 1000 μF | Filtering, timing |
| Film | 100 pF - 10 μF | Audio, precision timing |
| Characteristic | Description |
|---|---|
| Capacitance | Ability to store charge (measured in farads) |
| Voltage Rating | Maximum voltage the capacitor can withstand |
| ESR | Equivalent Series Resistance (lower is better) |
| Temperature Coefficient | How capacitance changes with temperature |
Given: 2 μF, 5 μF, 10 μF in series
Note: Series connection always results in a total capacitance less than the smallest individual capacitor.
Given: 2 μF, 5 μF, 10 μF in parallel
Note: Parallel connection results in a total capacitance equal to the sum of all individual capacitors.
Capacitors combine in exactly the opposite way to resistors — a point that trips up many beginners. In parallel, capacitances simply add: Ctotal = C1 + C2 + …, giving a total larger than any single capacitor (you are effectively enlarging the plate area). In series, the reciprocals add: 1/Ctotal = 1/C1 + 1/C2 + …, giving a total smaller than the smallest capacitor (you are effectively increasing the plate spacing).
Capacitance grows with plate area and shrinks with plate separation. Putting capacitors in parallel is like widening the plates, so capacitance increases; putting them in series stacks the gaps, so capacitance decreases. Charge is the key: in a series string every capacitor holds the same charge, and since V = Q/C the smallest capacitor takes the largest share of the voltage — important when combining capacitors to withstand a higher voltage.
Series connection not only lowers capacitance, it also raises the voltage the combination can withstand, because the applied voltage divides across the capacitors. This is used to build high-voltage capacitor banks from lower-voltage parts (with balancing resistors to share the voltage evenly). Parallel connection, by contrast, keeps the voltage rating the same but increases total capacitance and energy storage.
Bulk energy storage and power-supply smoothing (parallel), high-voltage capacitor banks (series), tuning and timing networks, and hitting non-standard capacitance values from the parts you have on hand.
Why is series capacitance smaller, unlike resistors? Because capacitance is inversely related to plate spacing; stacking capacitors in series behaves like a bigger gap. It is the mathematical mirror of resistors.
How do I get a higher voltage rating? Put capacitors in series (with balancing resistors); the voltage splits between them, though total capacitance drops.
The rules are reversed from resistors, which is the single most common source of confusion:
The physical reason is straightforward. Capacitance is proportional to plate area, so connecting capacitors in parallel is effectively making the plates bigger. Connecting them in series effectively increases the separation between the outer plates, which reduces capacitance.
Capacitors are put in series to withstand a higher voltage than any one part can take — common in high-voltage DC links. But the voltage does not divide equally unless the capacitors are identical, because in steady state it divides according to leakage resistance, not capacitance.
Leakage varies considerably between nominally identical parts, so one capacitor can end up with far more than its share and fail, which then overvolts the remaining ones in a cascade. The standard remedy is a balancing resistor across each capacitor, sized so its current is several times the worst-case leakage, which forces the voltage to divide by the resistor ratio instead.
Different capacitor types have different ESR and self-resonant frequencies, so a large electrolytic handles low-frequency bulk energy while small ceramics handle high-frequency transients. Paralleling them covers a wider frequency range than either could alone.
There is a caveat: the inductance of a ceramic in parallel with the capacitance of a bulk part can form a resonance, producing an impedance peak at some intermediate frequency rather than the smooth low impedance intended. Checking the combined impedance curve, rather than assuming parallel capacitors simply add, is the professional approach.
They add directly: C = C1 + C2 + …. This is the opposite of resistors, and corresponds physically to increasing the effective plate area.
Reciprocally: 1/C = 1/C1 + 1/C2 + …, so the total is smaller than the smallest capacitor. Series connection effectively increases plate separation.
To withstand a higher voltage than any single part is rated for, which is common in high-voltage DC links. The trade-off is reduced total capacitance.
Because in steady state the voltage divides according to leakage resistance rather than capacitance, and leakage varies between parts. A resistor across each capacitor, carrying several times the worst-case leakage, forces an even split.
They cover different frequency ranges. A large electrolytic handles low-frequency bulk energy; small ceramics handle fast transients. Together they give lower impedance across a wider band.
Yes. The inductance of one part can resonate with the capacitance of another, producing an impedance peak rather than the intended smooth low impedance. Checking the combined impedance curve is worthwhile in critical designs.