Series & Parallel Calculator
Add as many resistors or capacitors as you like, choose series or parallel, and get the combined value instantly
Add the resistor values below. In series they add up; in parallel the reciprocals add. You can type shorthand like 4k7 too.
About this tool
This calculator combines any number of resistors or capacitors in series or in parallel and shows the result with the exact formula. Resistors in series add together, while in parallel their reciprocals add. Capacitors behave the opposite way: in parallel they add, and in series their reciprocals add. Choose a component type, pick series or parallel, add as many values as you need, and the combined resistance or capacitance is calculated instantly. Each field has its own unit selector (Ω, kΩ, MΩ for resistors and F, µF, nF, pF for capacitors), and you can also type engineering shorthand such as 4k7 for 4.7 kΩ. It is built for makers, electronics students and hobbyists who want fast, dependable answers.
How to use
- 1 Choose whether you are combining resistors or capacitors.
- 2 Select series or parallel for how the components are connected.
- 3 Enter each value and pick its unit; use Add value for more, or the trash icon to remove one.
- 4 Read the combined total and the formula, and use Reset to start over.
How it works
For resistors in series the total resistance is the sum of all values: R = R1 + R2 + … For example 100 Ω, 200 Ω and 300 Ω in series give 600 Ω. For resistors in parallel the reciprocal of the total equals the sum of the reciprocals: 1/R = 1/R1 + 1/R2 + …, so two 100 Ω resistors in parallel give 50 Ω, and 2 kΩ, 3 kΩ and 6 kΩ in parallel give 1 kΩ. Capacitors follow the dual rule. In parallel the capacitances add: C = C1 + C2 + …, so 10 µF and 20 µF in parallel give 30 µF. In series the reciprocals add: 1/C = 1/C1 + 1/C2 + …, so two 2 µF capacitors in series give 1 µF. The calculator works internally in base units (ohms and farads) and then formats the result with a convenient prefix.
Frequently asked questions
How do resistors combine in series and parallel?
In series resistances add directly: R = R1 + R2 + … In parallel the reciprocals add, so 1/R = 1/R1 + 1/R2 + … The parallel total is always smaller than the smallest individual resistor.
Why are capacitors the opposite of resistors?
Capacitance depends on plate area and spacing. Placing capacitors in parallel effectively increases the area, so capacitances add. In series the spacing adds up, reducing capacitance, so the reciprocals add — exactly the mirror image of resistors.
Can I add more than two components?
Yes. Use Add value to include as many resistors or capacitors as you need. The series and parallel formulas extend to any number of components, and the running total updates instantly.
What does notation like 4k7 mean?
It is engineering shorthand where the unit letter replaces the decimal point. 4k7 means 4.7 kΩ, 100R means 100 Ω, and 2M2 means 2.2 MΩ. You can type it directly into any resistor field, or simply use the unit selector instead.
Related tools and uses
Pair this with the Ohm's law calculator to find voltage, current and power, the resistor color code tool to read physical parts, and the scientific notation converter for very large or small values.