Series & Parallel Calculator
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Combine resistors, capacitors, and inductors with the right formulas.
Free Series & Parallel Calculator Online — Big Das
Combining components in series or parallel is one of the first skills in electronics, yet it's easy to mix up the rules when capacitors enter the picture. The Big Das Series & Parallel Calculator handles resistors, capacitors, and inductors correctly, giving you the equivalent value as you type.
Paste a list of component values, choose series or parallel, and get the answer instantly — no calculator app, no spreadsheets, just results.
What Are Series and Parallel Connections?
Components in a circuit can be connected in two basic ways:
- Series — Current flows through each component in turn, one after another.
- Parallel — Current splits and flows through all components simultaneously, then recombines.
Resistors, capacitors, and inductors each behave differently under these two configurations. Resistors and inductors follow the same rules, but capacitors swap them around.
Why Does It Matter?
You might need a non-standard resistance, want to increase capacitance, or need to share voltage across multiple inductors. Knowing the equivalent value lets you design circuits with parts you already have on hand.
How to Use the Series & Parallel Calculator
- Choose the component type — Resistors, Capacitors, or Inductors.
- Choose the connection — Series or Parallel.
- Enter the values — Type or paste individual values separated by commas, spaces, or new lines. Use base units: ohms (Ω), farads (F), or henrys (H).
- Read the result — The equivalent value updates live, shown in the most readable SI prefix.
The Formulas Used
Resistors
- Series:
Req = R1 + R2 + R3 + … - Parallel:
1/Req = 1/R1 + 1/R2 + 1/R3 + …
Capacitors
- Series:
1/Ceq = 1/C1 + 1/C2 + 1/C3 + … - Parallel:
Ceq = C1 + C2 + C3 + …
Inductors
- Series:
Leq = L1 + L2 + L3 + … - Parallel:
1/Leq = 1/L1 + 1/L2 + 1/L3 + …
The pattern is easy to remember: resistors and inductors behave the same way, while capacitors do the opposite.
Worked Example
You have three resistors: 100 Ω, 220 Ω, and 470 Ω.
*In series:
Req = 100 + 220 + 470 = 790 Ω
*In parallel:
1/Req = 1/100 + 1/220 + 1/470 = 0.01 + 0.00455 + 0.00213 ≈ 0.01668
Req ≈ *60 Ω
Now try two capacitors in parallel: 1 µF and 0.1 µF.
Ceq = 1 + 0.1 = *1.1 µF
The same two capacitors in series:
1/Ceq = 1/1 + 1/0.1 = 1 + 10 = 11
Ceq ≈ 0.0909 µF = 90.9 nF
Common Use Cases
- Custom resistance: Create a 333 Ω load from three 1 kΩ resistors in parallel.
- Filter tuning: Combine capacitors to hit an exact cutoff frequency for an RC filter.
- Inductor substitution: Replace a missing inductor with a series combination of smaller ones.
- Voltage sharing: Connect capacitors in series to withstand higher voltages.
- Current sharing: Connect resistors in parallel to dissipate more power safely.
Frequently Asked Questions
Why do capacitors behave opposite to resistors?
Capacitance measures the ability to store charge. Adding plates in parallel increases the effective plate area, so capacitance adds directly. In series, the effective separation between plates increases, so capacitance decreases reciprocally.
Can I mix different component types?
No. A single calculation should use only resistors, only capacitors, or only inductors. Combining different types creates impedance networks that require AC analysis with complex numbers, which is beyond this tool's scope.
What units should I enter?
Enter base units: ohms for resistors, farads for capacitors, and henrys for inductors. The result is automatically formatted with SI prefixes like kΩ, µF, or mH for readability.
What happens if I enter zero or a negative value?
Zero resistance in a parallel network creates a short, and zero capacitance or inductance is physically meaningless. The tool requires all values to be positive and shows an error for any entry that isn't.
Is there a limit to how many values I can enter?
There's no hard limit — the calculator handles as many values as you paste into the box. Practical circuits rarely need more than a handful, but the math scales indefinitely.
Why does my parallel equivalent look smaller than any single part?
That's correct physics. Parallel paths give current more ways to flow, so the total resistance or inductance drops below the smallest individual value. For capacitors in series, the same reciprocal rule produces an equivalent smaller than the smallest capacitor.